EEVblog Electronics Community Forum
Electronics => Power/Renewable Energy/EV's => Topic started by: paul_g_787 on April 16, 2021, 05:51:30 pm
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Hi. I am wondering if someone can offer some insight into what might be causing this problem and what I can do to get it resolved.
I have been having problems with high mains supply voltage. It usually hangs out at 249-252V but at night, almost every night I can get 255V - 262V. I have also seen it go to 263V, 268V and 315V on three occasions. :bullshit: :bullshit: :bullshit: When it went to 315V it blew up my UPS (APC BR1500GI) which now has an F02 output short. (Will look at fixing this later).
I have contacted my electricity supplier (British Gas) and they just hang up the phone or fob me off.
I have contacted UK Power Networks countless times and they have sent round and Electrician on 2 occasions to inspect the Wiring before and after the electricity meter, both times finding no faults. (We have TNCS wiring).
So I complained again and they sent round an engineer to fit a Voltmeter before the electricity meter which was here for a month. The results (which I have a copy of somewhere) and the accompanying letter confirm that my voltage continuously exceeds the maximum of 253 on multiple occasions. However no action has yet been taken (over a year later) and last night I was woke up and 4am by my three UPS units beeping with a voltage of 261V!!!
Despite having 2 of their electricians verify there are no problems with my house wiring, and also verifying the voltage from before the electricity meter with my house disconnected, one thing that the UK Power Networks have repeatedly told me is that it may be the house wiring causing the voltage to go up due to a poor connection. However surely a poor connection would lower the voltage? I asked the second of their electricians about this and he just looked at me blankly and couldn't answer. And they also can't explain why the voltage was so high with the house disconnected.
I have been taking the readings from the voltmeters on 3 APC UPS and also my Fluke DMM. All of these meters, and also the one from the Electricity company from that time, are all within <0.1V of each other.
Can anyone make a suggestion what I should do? I am very concerned about this potentially causing a fire.
Additionally whenever it goes above 254V the central heating timer crashes and needs to be manually rebooted. This is very annoying.
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I wonder if a neighbour has an EV charger - a high overnight load on a different phase, and a less-than perfect neutral might cause this.
Might be interesting to measure the voltage between your TNCS earth and "real" earth outside - a significant voltage might indicate a Neutral issue outside
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Try something like this:
https://www.ombudsman-services.org/sectors/energy (https://www.ombudsman-services.org/sectors/energy)
?
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Can anyone make a suggestion what I should do?
send british gas invoices for all the electrical equipment damaged by the over voltage starting with the ups
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Despite having 2 of their electricians verify there are no problems with my house wiring, and also verifying the voltage from before the electricity meter with my house disconnected, one thing that the UK Power Networks have repeatedly told me is that it may be the house wiring causing the voltage to go up due to a poor connection. However surely a poor connection would lower the voltage? I asked the second of their electricians about this and he just looked at me blankly and couldn't answer. And they also can't explain why the voltage was so high with the house disconnected.
I think Mike has a good observation here. The stability of your mains voltage depends strongly on having a good solid neutral connection back to the substation transformer. This neutral is like an "anchor" that keeps the voltage where it should be. If there was any kind of neutral fault between you and the substation, and there was an unbalanced load on another phase, then your voltage could get pushed up.
That said, if there is a neutral fault it would more likely be out in the street and not inside your property boundary.
I think you have to keep chasing your local DNO (UK Power Networks?) and push them to do something. You need to get their engineering staff involved. Complaining to British Gas won't help as they only sell you the electricity, they don't supply it.
It seems like if you have already had your voltage recorded by the supply company there is evidence of a problem. If they are not acting, you need to escalate--Regulator? Ombudsman?
Good luck.
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There is very little you can do, technically. The problem is technical, but something you can't fix because the problem likely isn't in equipment you own, and you are not allowed to fix it. So the problem is only bureaucratic. By refusing to fix it, the power company is actually making it political. I don't see any other choice than to find out what authority is responsible for overseeing power companies. It seems you need legal advice, I'm pretty sure some authority offers it for consumers free of charge.
I would likely inform the power company that due to the inability to provide their part of the agreement (i.e., supply electric power within specifications), I see the contract is void from now on. Then install a massive genset to supply your needs, until the electric company is able to provide you power again.
This gets interesting if law requires you to buy energy from the grid. You can't satisfy this law if the power company can't supply you, anyway, but apparently everything is seemingly well as long as the power company is able to invoice you.
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Hello
Check out the notorious UK "Ring Bus" distribution system. Well known for very high line voltages.
Deep in the UK regulations there may exist a legal limmit to line voltage. You can inform your UK Govt representative of any excess beyond the regulatory limit.
We use line monitors and regulators if the voltage is too high.
A simple buck autotransformer can bring it down by 3-20%.
A Variac variable transformer is not as efficient or as compact but can work.
Kind Regards,
Jon
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Well, if there is a lot of load on 2 phases out of 3, that can shift the neutral. If there is really bad wiring on your feed. (outside the house, in your street)
I would document the overvoltage, and sue the DSO.
Or maybe there is a customer protection group, that you should contact.
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Would it be sensible to sue your energy supplier or UK Power Networks via the small claims court every time a piece of your equipment is broken? But you'd probably have to show due diligence to get your money back before going ahead with court proceedings.
Obviously you'd be liable for their legal costs if they win, but if you have THEIR evidence of a fault I'd find it hard to believe you'd lose.
As long as you get payment each time you would only lose your time. Hopefully eventually someone responsible fixes the fault.
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Would it be sensible to sue your energy supplier or UK Power Networks via the small claims court every time a piece of your equipment is broken? But you'd probably have to show due diligence to get your money back before going ahead with court proceedings.
Obviously you'd be liable for their legal costs if they win, but if you have THEIR evidence of a fault I'd find it hard to believe you'd lose.
As long as you get payment each time you would only lose your time. Hopefully eventually someone responsible fixes the fault.
Why would you want to go to court.
You sue them, they will either fix your problem, or settle. Why would they want to go to court.
Its about getting their attention.
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Ofgem?
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Hello again: Lawsuits are useless here and only make money for the lawyers.
Often the regulations are loosened with time.
https://www.twothirtyvolts.org.uk/pdfs/site-info/Explanation_230Volts.pdf (https://www.twothirtyvolts.org.uk/pdfs/site-info/Explanation_230Volts.pdf)
I think the applicable PRE BREXIT reg of EU was European Standard EN50160. = 207 Volts to 253 Volts. That may change post Brexit!
High VARS (excess capacitance eg from PFC) can cause resonant voltage rise in HV transmission and distrib line.
I would document the issues with a 24/7 line V monitor, for a few weeks, then send the chart with max/min leagl V outlined to the Sys Op of the local utility and to a local lawmaker, noting that the high line V can pose a danger to consumers.
Kind Regard,
Bon Chance
Jon
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UK Power Networks are the ones to deal with here, the fault is with their network, and it's their responsibility to fix it. British Gas won't be the slightest bit interested, but if they were all they could do is lean on UKPN on your behalf. Usually the problem is getting them to accept that there is a fault - inaction after getting clear evidence from a logger they installed is unusual. To me this suggests they know what it is and that it's a network design issue rather than a fault as such (and therefore very expensive to fix). If it was a high resistance neutral joint they would have fixed it by now because that causes a lot of other problems, and would be likely to get progressively worse.
On a technical level it seems very likely that you're on a part of the network with a relatively high impedance, if they could simply have changed a transformer tapping down then they would probably have done so already - most likely they can't because then at other times of day the voltage would be too low, not necessarily for you but for some customers on the same transformer. A large overnight load that is on another phase is the most likely cause as others have said, in conjunction with a fairly high resistance neutral, probably not faulty just long and thin. Unbalanced loads on the local HV network would could also cause this, but this is less likely. Basically it sounds like your area is in need of expensive network reinforcement and they're trying to avoid it.
The upper limit is 253 V, it's set in the The Electricity Safety, Quality and Continuity Regulations 2002 and will not be changing due to Brexit. https://www.legislation.gov.uk/uksi/2002/2665/regulation/27/made (https://www.legislation.gov.uk/uksi/2002/2665/regulation/27/made) This is the piece of legislation that they must comply with to avoid heavy fines, and it's what you will need to use to beat them up with. Essentially you need to write to them with the evidence that they are in breach of their obligations and then take it to Ofgem if they ignore you. Separately you can also take them to small claims court for damage to appliances, etc. but only once you have tried the other methods. For those not familiar with the process, in the UK there is a specific procedure you can use for claims under £10,000 which is designed to be low cost and complexity and which does not require you to have legal representation. They specifically cannot claim for their legal fees if you loose, your liability is limited to their reasonable expenses for time, etc. Often big companies just no-show as it's not worth their time and you win by default, see here: https://www.moneysavingexpert.com/reclaim/small-claims-court/ (https://www.moneysavingexpert.com/reclaim/small-claims-court/)
I'm guessing you're somewhere relatively rural and a single-phase customer? Perhaps with overhead distribution, and maybe even on a split phase piece of network? How far are you from the transformer? Is it large or small, does it have 2 HV bushings or 3? Is it rusty (usually indicates severely overloaded, the paint burns off at a lower temperature than the transformer actually fails)? What's your earthing system (do they supply an earth terminal or do you have a rod)?
How low does your mains voltage dip at other times? If not too low then as an interim fix you could buy and install a transformer that takes ~10% off your incoming voltage for a couple of hundred quid, it's far from ideal, but if it stops expensive things failing it might be worth it.
The 315 V is the most worrying, high enough to cause damage, and also more suggestive of a bad neutral joint somewhere than just a general high resistance. It is possible that they've fixed a neutral joint quietly, preventing the 315 V but leaving you with the ~270 V. Options to force disconnection at high voltage exist, but are a bit ugly.
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Hello again: Lawsuits are useless here and only make money for the lawyers.
Does the UK have small claims court though? The US has "small claims court" to settle up smaller grievances, where there's no lawyers for individuals, formality on procedures is a bit more lax given that., and associated costs are lower.
For the OP, sounds like they are more than willing to provide you enough evidence, checking out your wiring saying it's fine, (even better that its their representative saying that) acknowledging their problem after the logging.
You can also try the "woe is me I'm sleep in fear every night that the power company is going to set my fridge on fire and burn down my house" angle with the local news. Get a meter in the wall reading an excessively high voltage and do your best to ham up some B-roll footage for the news, and talk to them about devices that keep getting burned up and how you feel helpless and no one will do anything etc. Has enough drama and anger inducing aspects that they may pick up the story for a slow night.
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315V is really nasty. Most products have not even been type tested at such a high continuous voltage, and for a good reason. Almost anything with a MOV at the inlet is going to get that MOV seriously hot at 315V.
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Broken PEN conductor? Rare, but does happen. This would allow for a shift between your local earth and the substation earth, especially if your local earth isn't very good.
Difficult to detect as a broken PEN conductor could lie beyond your premises. Did they specifically check for PEN fault?
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Similarly a few years back I had a new AC unit installed, and the 24V control fuse kept popping every day, with no resolution from the installation company other than coming everyday to replace it and try to persuade me into buying their mains voltage stabilizer and damage insurance.
Again I had to dig into the problem myself and found out the control wire bundle had some insulation damages and instructed the technician to rewire the thing using some spare strands to replace the bad ones, since then the AC never failed again AFAIK till I sold the house.
As the previous case, I paid more than generously, I paid all $5000 they had asked for without a question for a $1700 Goodman unit, and that's what I got from a $3300 service fee.
Not sure about how it is in China, but in the US, it really sounds like DIY would be the way to go even after factoring in the cost of tools and time to learn how to do it right including getting an EPA 608.
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I wonder if a neighbour has an EV charger - a high overnight load on a different phase, and a less-than perfect neutral might cause this.
Might be interesting to measure the voltage between your TNCS earth and "real" earth outside - a significant voltage might indicate a Neutral issue outside
EV home charging doesn't use that much electricity. I've had many discussions with people in the UK about EV charging, but I don't recall the numbers. However, it is not so much different from using two or three tea kettles at once and is comparable to the central hot water heater being on. My water heater is 4.4 kW. Charging my car on a 40 amp circuit would use about 8 kW. If one user on a three phase supply with each home only getting a single phase would see a smaller rise in voltage than the high current user sees as a drop because of the three phases being 120 degrees out of phase and not 180.
I think what might be happening is simply the net loading on the transformer. At night it is lower, so you will see a higher voltage due to lower resistive losses as will the other homes. This would be similar to disconnecting your house load making the voltage on the line rise.
I used to be in a UK ham mailing group called RSGBtech. I recall lots of similar discussions and in particular someone was able to resolve such an over voltage. Maybe you could ask there how the guy got the power company to adjust the transformer. They have multiple taps just for this purpose.
https://groups.io/g/RSGBTechnical
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I wonder if a neighbour has an EV charger - a high overnight load on a different phase, and a less-than perfect neutral might cause this.
Might be interesting to measure the voltage between your TNCS earth and "real" earth outside - a significant voltage might indicate a Neutral issue outside
EV home charging doesn't use that much electricity.
32A/7kW typically
I've had many discussions with people in the UK about EV charging, but I don't recall the numbers. However, it is not so much different from using two or three tea kettles at once and is comparable to the central hot water heater being on.
The difference is that it's a continuous load for many hours - most others are either short term (kettle/shower) , or cycling on/off (oven, heating)
I think what might be happening is simply the net loading on the transformer. At night it is lower, so you will see a higher voltage due to lower resistive losses as will the other homes. This would be similar to disconnecting your house load making the voltage on the line rise.
Probably the most likely, but not for going as high as 315V - that looks more like a neutral issue
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I wonder if a neighbour has an EV charger - a high overnight load on a different phase, and a less-than perfect neutral might cause this.
Might be interesting to measure the voltage between your TNCS earth and "real" earth outside - a significant voltage might indicate a Neutral issue outside
EV home charging doesn't use that much electricity.
32A/7kW typically
I've had many discussions with people in the UK about EV charging, but I don't recall the numbers. However, it is not so much different from using two or three tea kettles at once and is comparable to the central hot water heater being on.
The difference is that it's a continuous load for many hours - most others are either short term (kettle/shower) , or cycling on/off (oven, heating)
Not sure what you mean. The hot water heater can be on for an hour easily when people use the shower. My furnace has a 10 kW heating coil. That's more than my car will draw other than at a Supercharger and there are times when it runs all night trying to keep up with the winter cold.
Even for short duration loads, the point is the car is not much more of an impact to the line voltage.
We don't have the same issue in the US with unbalances in the distributed power. The final run is typically a high voltage single phase pair with a transformer to step down from maybe 7 kV to 240 volts as a split phase that runs to one to four houses typically. One house drawing more power than the others never unbalances the voltages.
In reality, none of that matters. If a customer is using power and it causes the voltage to be excessive at another customer's premise, that is a fault in the power distribution.
I think what might be happening is simply the net loading on the transformer. At night it is lower, so you will see a higher voltage due to lower resistive losses as will the other homes. This would be similar to disconnecting your house load making the voltage on the line rise.
Probably the most likely, but not for going as high as 315V - that looks more like a neutral issue
I guess someone really likes tea... late at night.
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Not sure what you mean. The hot water heater can be on for an hour easily when people use the shower. My furnace has a 10 kW heating coil.
The vast majority of properties in the UK use gas, and most people do not take hour long showers.
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Not sure what you mean. The hot water heater can be on for an hour easily when people use the shower. My furnace has a 10 kW heating coil.
The vast majority of properties in the UK use gas, and most people do not take hour long showers.
So how does any of that affect EV charging???
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Not sure what you mean. The hot water heater can be on for an hour easily when people use the shower. My furnace has a 10 kW heating coil.
The vast majority of properties in the UK use gas, and most people do not take hour long showers.
So how does any of that affect EV charging???
If the car is set to charge very late at night when almost all other loads are not present and there's a bad neutral you could see a serious excess voltage event on other phases. Same with any other large load, but I'll give you a guess what relatively unusual and new large, overnight load is being seen on the networks..
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Not sure what you mean. The hot water heater can be on for an hour easily when people use the shower. My furnace has a 10 kW heating coil.
The vast majority of properties in the UK use gas, and most people do not take hour long showers.
So how does any of that affect EV charging???
If the car is set to charge very late at night when almost all other loads are not present and there's a bad neutral you could see a serious excess voltage event on other phases. Same with any other large load, but I'll give you a guess what relatively unusual and new large, overnight load is being seen on the networks..
You pointed out the problem, "bad neutral". Get that fixed!
One more reason why I'm glad I'm in the US. The neutral doesn't carry any major loads.
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You pointed out the problem, "bad neutral". Get that fixed!
That has been the point of discussion from the beginning. You just haven't been able to see past your assumption EVs were being blamed.
One more reason why I'm glad I'm in the US. The neutral doesn't carry any major loads.
And yet a bad neutral on a property in the US causes very much the same problem.
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One more reason why I'm glad I'm in the US. The neutral doesn't carry any major loads.
I think a few data centers went up in flames because of that assumption, before PFC became relatively normal on PSUs. If you have a three-phase wye supply feeding PSUs without PFC, the current in the neutral will be 3X that in the phases when you otherwise would expect near zero. And on certain allowed-but-shouldn't-be configurations in residential use (home runs with shared neutral), losing neutral can cause your 120V socket to be 240 volts and that can be very exciting.
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One more reason why I'm glad I'm in the US. The neutral doesn't carry any major loads.
I think a few data centers went up in flames because of that assumption, before PFC became relatively normal on PSUs. If you have a three-phase wye supply feeding PSUs without PFC, the current in the neutral will be 3X that in the phases when you otherwise would expect near zero. And on certain allowed-but-shouldn't-be configurations in residential use (home runs with shared neutral), losing neutral can cause your 120V socket to be 240 volts and that can be very exciting.
You will need to explain that one.
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One more reason why I'm glad I'm in the US. The neutral doesn't carry any major loads.
I think a few data centers went up in flames because of that assumption, before PFC became relatively normal on PSUs. If you have a three-phase wye supply feeding PSUs without PFC, the current in the neutral will be 3X that in the phases when you otherwise would expect near zero. And on certain allowed-but-shouldn't-be configurations in residential use (home runs with shared neutral), losing neutral can cause your 120V socket to be 240 volts and that can be very exciting.
You will need to explain that one.
Which one?
On a single split-phase system: Suppose you have two 120 volt circuits that are on opposite sides and share a neutral. You plug a space heater and a light bulb into each circuit and you have a balance--no neutral current. Then your neutral breaks or becomes disconnected--nothing happens, still balanced. Then one space heater turns off--what happens to the light bulb on that circuit?
On the three phase example: If you have a 208/120 wye three-phase service for three-phase and single-phase use, you normally size the neutral the same as the phases. If only one phase has a load, then that phase and the neutral see the same current. If you add some load to the other phases, the neutral current goes down. If they are all equally loaded, the neutral current is zero. That's the theory anyway, and it works as long as the current waveform is more or less sinusoidal, phase doesn't matter as long as they are all the same too.
A non-PFC PSU, or anything powered with rectifier and filter capacitor, has a completely non-sinusoidal current load. A nominal current of 1 amp might actually be a peak current of 3 amps with a 60-degree conduction angle (120 degrees per cycle) which results in 3X the I2R heating. That is would affect both phase and neutral and is the reason these types of devices usually require derating of the service wiring. However, if you connect these to your three-phase service, you might think the load would balance out--and some people did think that. However, since the conduction periods don't overlap, adding a load like this to the other phases doesn't result in the neutral current going down, rather they add. So if you were completely unaware of the way these devices work and you expected the load to react the same as say incandescent lighting or induction motors, you end up with 3X the anticipated I2R heating on the phases and 9X on the neutral. This could theoretically happen with any load with a very poor harmonic power factor, perhaps lighting ballasts or other things. But I've only really heard about it with data centers.
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Not sure what you mean. The hot water heater can be on for an hour easily when people use the shower. My furnace has a 10 kW heating coil.
The vast majority of properties in the UK use gas, and most people do not take hour long showers.
So how does any of that affect EV charging???
In the UK, in non-gas houses, domestic stored water heating is typically 3 kW heating a ~200 L low-pressure tank. Instant heating for showers is also common often around 7- 10 kW and is often found in houses that do have gas as it's a cheap way to add an extra shower and is at mains pressure. The most likely candidate for high loads at night is not EV charging but storage heaters, 5-10 kW for up to 7 hours overnight heating some big ceramic bricks on cheap(ish) night rate electricity for later use as daytime heat. The electric car thing is probably a red herring.
I still think it's more likely to be a generally high resistance neutral from being long and thin and underspec'd for the loads rather than a faulty joint. A bad joint would most likely have been fixed or caught fire by now. Historically undersized neutrals were common on the assumption of at least some balance between phases and before anyone worried about harmonic currents (1960s and earlier).
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Yes undersized neutral was common when the high power loads were all resistive or inductive, like heating and motor loads, so the neutral only had to carry a difference current equal to the household current rating over the 3 phase set of connections. Typically was 60% of the conductor diameter for the phases, and the same for the PE conductor, though TNC-S uses the same conductor instead. done when copper prices peaked, to lower the cost of building out networks for the utility operators and municipalities. That changed when switching supplies became common, and the first use was in TV sets, where you suddenly had large DC current flows in the neutral, and this accumulated as the TV sets tended to turn on the thyristor power supplies late in the voltage waveform, so the neutral current was massive. Led to quite a few substations blowing up as the DC current flow through the windings saturated the core, and then in turn the primary side current was not limited, except by the winding resistance and the lower air core inductance, leading to massive heating and failure.
The current thing is to size neutral to the same as phase conductor, though with increasing use of PFC for larger loads the neutral current ca be lower, but there are still large numbers of loads with poor power factor, including LED lights, especially those with trailing edge dimming, as you get pretty high current flow where the corresponding other 2 phases are not going to draw current out via the neutral. A lot of cheaper appliances also forego PFC, because that makes them cheaper, and thus you get the high peak current pulses.
If the high mains is all of a sudden, and there are no new developments by you, then it is a failing neutral, and you are on the lowest loaded phase, or the neutral at the substation is burnt out already, and open circuit, or the cable has been stolen. Complain to the power company again, and to your local municipality that your house and equipment is at risk, and that you will have damaged equipment from this, along with the increased risk of a fire from failed equipment.
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Claiming for damaged items on your insurance may also help as there's a good chance the insurer will then try to recover costs from UKPN - might make them pay attention.
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UK Power Networks are the ones to deal with here, the fault is with their network, and it's their responsibility to fix it. British Gas won't be the slightest bit interested, but if they were all they could do is lean on UKPN on your behalf. Usually the problem is getting them to accept that there is a fault - inaction after getting clear evidence from a logger they installed is unusual. To me this suggests they know what it is and that it's a network design issue rather than a fault as such (and therefore very expensive to fix). If it was a high resistance neutral joint they would have fixed it by now because that causes a lot of other problems, and would be likely to get progressively worse.
On a technical level it seems very likely that you're on a part of the network with a relatively high impedance, if they could simply have changed a transformer tapping down then they would probably have done so already - most likely they can't because then at other times of day the voltage would be too low, not necessarily for you but for some customers on the same transformer. A large overnight load that is on another phase is the most likely cause as others have said, in conjunction with a fairly high resistance neutral, probably not faulty just long and thin. Unbalanced loads on the local HV network would could also cause this, but this is less likely. Basically it sounds like your area is in need of expensive network reinforcement and they're trying to avoid it.
Yes, I have suspected that there is an issue that they know about which they are not willing to fix. I live in a small village, well now it is technically a town. They have built several housing estates here over the last 5 years and I suspect that the wiring to our town is just not 'big' enough to cope.
The upper limit is 253 V, it's set in the The Electricity Safety, Quality and Continuity Regulations 2002 and will not be changing due to Brexit. https://www.legislation.gov.uk/uksi/2002/2665/regulation/27/made (https://www.legislation.gov.uk/uksi/2002/2665/regulation/27/made) This is the piece of legislation that they must comply with to avoid heavy fines, and it's what you will need to use to beat them up with. Essentially you need to write to them with the evidence that they are in breach of their obligations and then take it to Ofgem if they ignore you. Separately you can also take them to small claims court for damage to appliances, etc. but only once you have tried the other methods. For those not familiar with the process, in the UK there is a specific procedure you can use for claims under £10,000 which is designed to be low cost and complexity and which does not require you to have legal representation. They specifically cannot claim for their legal fees if you loose, your liability is limited to their reasonable expenses for time, etc. Often big companies just no-show as it's not worth their time and you win by default, see here: https://www.moneysavingexpert.com/reclaim/small-claims-court/ (https://www.moneysavingexpert.com/reclaim/small-claims-court/)
I'm guessing you're somewhere relatively rural and a single-phase customer? Perhaps with overhead distribution, and maybe even on a split phase piece of network? How far are you from the transformer? Is it large or small, does it have 2 HV bushings or 3? Is it rusty (usually indicates severely overloaded, the paint burns off at a lower temperature than the transformer actually fails)? What's your earthing system (do they supply an earth terminal or do you have a rod)?
As I said, a small town, we about 3 miles from the 'big' town.
We have underground distribution.
I am less than 1 mile from the transformer.
I am not sure if it has 2 or 3 HV bushings or of the condition of the transformer as I have never seen it, it is in a small brick out building at the end of the street.
My earthing system is TNCS: so no rod.
How low does your mains voltage dip at other times? If not too low then as an interim fix you could buy and install a transformer that takes ~10% off your incoming voltage for a couple of hundred quid, it's far from ideal, but if it stops expensive things failing it might be worth it.
The 315 V is the most worrying, high enough to cause damage, and also more suggestive of a bad neutral joint somewhere than just a general high resistance. It is possible that they've fixed a neutral joint quietly, preventing the 315 V but leaving you with the ~270 V. Options to force disconnection at high voltage exist, but are a bit ugly.
The voltage, the lowest I see it on average is about 245V and that is lately during lockdown where everyone is at home. Before last March never lower than 248.
The electrician that came round last year before the voltage logger was installed told me that I am on one of 3 phases. I am the last house on the phase and that the transformer is set to 249V (Which is what I usually get). He disconnected my house from the supply and tested the connections and concluded the fault is further up the line, then he booked the voltage logger to be installed.
So this suggests to me that the wiring from the transformer is fine.
I highly suspect that they are setting the voltage higher to cope for the increased load from the new build estates. Although this is just suspicion and I have nothing to prove this.
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You will need to explain that one.
Google zero sequence current.
You have not been paying attention. in the US we do not bring three phase into the home.
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One more reason why I'm glad I'm in the US. The neutral doesn't carry any major loads.
I think a few data centers went up in flames because of that assumption, before PFC became relatively normal on PSUs. If you have a three-phase wye supply feeding PSUs without PFC, the current in the neutral will be 3X that in the phases when you otherwise would expect near zero. And on certain allowed-but-shouldn't-be configurations in residential use (home runs with shared neutral), losing neutral can cause your 120V socket to be 240 volts and that can be very exciting.
You will need to explain that one.
Which one?
On a single split-phase system: Suppose you have two 120 volt circuits that are on opposite sides and share a neutral. You plug a space heater and a light bulb into each circuit and you have a balance--no neutral current. Then your neutral breaks or becomes disconnected--nothing happens, still balanced. Then one space heater turns off--what happens to the light bulb on that circuit?
This is the same problem that is found with three phase circuits. Lose the neutral and the voltage seen is at the mercy of the load balance. In US homes, we put the big loads on 240 tied across the full voltage without a connection to neutral. So the loads are much better balanced in general than running one of three phases to each home where one home can greatly unbalance the loads and muck the voltage to the other homes.
On the three phase example: If you have a 208/120 wye three-phase service for three-phase and single-phase use, you normally size the neutral the same as the phases. If only one phase has a load, then that phase and the neutral see the same current. If you add some load to the other phases, the neutral current goes down. If they are all equally loaded, the neutral current is zero. That's the theory anyway, and it works as long as the current waveform is more or less sinusoidal, phase doesn't matter as long as they are all the same too.
A non-PFC PSU, or anything powered with rectifier and filter capacitor, has a completely non-sinusoidal current load. A nominal current of 1 amp might actually be a peak current of 3 amps with a 60-degree conduction angle (120 degrees per cycle) which results in 3X the I2R heating. That is would affect both phase and neutral and is the reason these types of devices usually require derating of the service wiring. However, if you connect these to your three-phase service, you might think the load would balance out--and some people did think that. However, since the conduction periods don't overlap, adding a load like this to the other phases doesn't result in the neutral current going down, rather they add. So if you were completely unaware of the way these devices work and you expected the load to react the same as say incandescent lighting or induction motors, you end up with 3X the anticipated I2R heating on the phases and 9X on the neutral. This could theoretically happen with any load with a very poor harmonic power factor, perhaps lighting ballasts or other things. But I've only really heard about it with data centers.
Yeah, non-linear loads are a bitch.
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From my experience as HV / LV electrician and electrical engineer the large variation in voltage between phase and neutral indicate that there is a bad connection in the PEN conductor. If you got a 3 phase installation in your house you can find if there are a bad connection in the PEN conductor by loading up one of the phases more than the oter ones and measure the voltage phase to neutral on all phases. If the voltage differs a lot between the phases there is something wrong on the PEN.
You will have to get the PEN conductor traced back its origin to find the fault, but its probably located where there are splices. A good place to start is in your fuse panel.
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From my experience as HV / LV electrician and electrical engineer the large variation in voltage between phase and neutral indicate that there is a bad connection in the PEN conductor. If you got a 3 phase installation in your house you can find if there are a bad connection in the PEN conductor by loading up one of the phases more than the oter ones and measure the voltage phase to neutral on all phases. If the voltage differs a lot between the phases there is something wrong on the PEN.
You will have to get the PEN conductor traced back its origin to find the fault, but its probably located where there are splices. A good place to start is in your fuse panel.
This is what other people above have thought. However, in the UK, houses do not get three phase service. You typically get three phases and a neutral carried down the street, and then each house gets just one of phases and the neutral brought into the property.
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From my experience as HV / LV electrician and electrical engineer the large variation in voltage between phase and neutral indicate that there is a bad connection in the PEN conductor. If you got a 3 phase installation in your house you can find if there are a bad connection in the PEN conductor by loading up one of the phases more than the oter ones and measure the voltage phase to neutral on all phases. If the voltage differs a lot between the phases there is something wrong on the PEN.
You will have to get the PEN conductor traced back its origin to find the fault, but its probably located where there are splices. A good place to start is in your fuse panel.
This is what other people above have thought. However, in the UK, houses do not get three phase service. You typically get three phases and a neutral carried down the street, and then each house gets just one of phases and the neutral brought into the property.
Irrelevant, it's a three phase supply.
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From my experience as HV / LV electrician and electrical engineer the large variation in voltage between phase and neutral indicate that there is a bad connection in the PEN conductor. If you got a 3 phase installation in your house you can find if there are a bad connection in the PEN conductor by loading up one of the phases more than the oter ones and measure the voltage phase to neutral on all phases. If the voltage differs a lot between the phases there is something wrong on the PEN.
You will have to get the PEN conductor traced back its origin to find the fault, but its probably located where there are splices. A good place to start is in your fuse panel.
This is what other people above have thought. However, in the UK, houses do not get three phase service. You typically get three phases and a neutral carried down the street, and then each house gets just one of phases and the neutral brought into the property.
Irrelevant, it's a three phase supply.
Please explain. How would a weak neutral in your consumer unit lead to excessive voltages in your home?
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Please explain. How would a weak neutral in your consumer unit lead to excessive voltages in your home?
It wouldn't, so that's one less place to look. The rest of the post stands.
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It wouldn't, so that's one less place to look. The rest of the post stands.
That's fine then, since my only comment is about looking for the fault in the fuse panel. The rest of the thread has gone over the possibility of a poor neutral connection outside the house several times. That's old news by now.
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I highly suspect that they are setting the voltage higher to cope for the increased load from the new build estates. Although this is just suspicion and I have nothing to prove this.
+1
Upgrading cabling 2.8x is not cheap.
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Failing joint in the cable, easiest way for the supplier to find is to go back to the transformer via all the pedestals, and measure the voltage on that particular phase, looking for when it suddenly drops back to 249VAC as set by the transformer, and the fault is between the 2. Otherwise a long wire on the neutral to allow direct measurement of voltage drop between each point will work as well, though it will need to be a long wire, but does not really carry current other than meter burden.
New estates the typical thing is to force the builder to pay for the cable from the local transformer to the estate boundary, as they are the ones requesting the service, they pay for the cable and nstallation. Had that, where a house wanted meter upgrade, and they had to pay for the new cable from the pole to the new meter box, as well as the cable after the meter, as part of the installation cost. Another, upgrade from 60A single phase to 80A 3 phase, and had to pay for the new 25mm 4 core SWA cable from the substation to the meter box, as the existing cabling was running at full loading in the street distribution. Luckily only 60m of cable needed, and pay for the metro to dig the ditch, and lay it as well.
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When the grid is TNC or TNC-S the load is put between phase and neutral. The first poster on this tread said it where a TNC-S system. https://electrical-engineering-portal.com/erection-procedures-of-earthing-arrangements-tnc-tn-s-tnc-s-and-tt (https://electrical-engineering-portal.com/erection-procedures-of-earthing-arrangements-tnc-tn-s-tnc-s-and-tt)
Also from the first posting the highest voltage where 300 and something volts indicating the grid is a 400V system (system voltage form 380v to 410v depending on country and delivery regulations for electrical power)
The voltage between phases are 380-410v and this gives a phase to neutral of 219v to 237v. This is a vectoral value (complex numbers) but very simplified its the voltage phase to phase divided by the root of 3 (1,73).
On a 400V TNC-S system a 230V load is placed between one phase and neutral and get a voltage somewhere around 230V. A 400V load would be placed between two of the phases, but these loads are usually a 3phase load so the neutral don't matter and would normally not be connected to the load.
The PEN conductor is tied to the mains transformer star point to clamp the neutral voltage at 230V level. TNC-S systems always got Y connected windings on the secondary side of the mains transformer.
When the neutral (N / PEN) is disconnected this is called "Floating neutral". When the neutral is floating the voltages between the phases and neutral is dependent of the balances on all loads connected to the same transformer/circuit. The loads would work as a voltage divider so that the phase with the lowest load can get a voltage to neutral very close to the phase to phase voltage.
If you got a connected PEN conductor the voltage between neutral and protective earth will be close to nothing (1-5V normally). Any voltages higher than this is a solid indication of bad connections to the PEN and Neutral conductor. Its possible to check this with a regular multimeter but don't use the cheepo types because these might not withstand a voltage of up to 400v, use one rated for at least 500V.
A broken PEN conductor can cause current to run in the installations main earth bar and metal pluming for gas and water and the current can have a hight level because sit the current form all consumers that is connected to the broken PEN (internal and external). This can give dangerous voltage when getting in contact with metal parts connected to the earth system in the building and also damages to soldered joints in the plumbing.
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The voltage between phases are 380-410v and this gives a phase to neutral of 219v to 237v. This is a vectoral value (complex numbers) but very simplified its the voltage phase to phase divided by the root of 3 (1,73).
And the voltages are even higher in this case. The UK supply is nominally 240/415 V, and in this case if the transformer is set to 249 V the phase voltage would be 431 V. Definitely not the kind of voltage you want getting into your house due to faults in the distribution system.
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So just to clarify.
As a previous commenter said, in the UK we have three phase in the street, and each home (usually alternately 1, 2, 3) receives a single phase and neutral.
The engineer from UK Power Networks informed me that we have a TNC-S installation at my house.
When the engineer checked my meter and connections to the distribution board, he confirmed there were no bad connections including the Neutral which he suspected when he first arrived.
He also took voltage readings at the other end of the cable in the transformer building and informed me he was seeing the same voltages as at my house. He concluded that the fault is not at my property and is not with the neutral or other poor connection.
He also informed me that the transformer is set to 249V, which is the lowest voltage I see usually during the day time around 6pm.
Then he booked the voltage recorder which was fitted inside my meter cabinet. This was installed for 4 weeks. I went to the meter three times a day (and night) and recorded the voltage on the LCD display. The readings were identical to the voltage readings I took from my UPS.
So what could the fault be at this point? I am assuming that it is a fault with the equipment in the transformer building?
I want to try to get my head around this before writing to UK power networks so I can fully understand what is going on so as to avoid getting fobbed off again.
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So what could the fault be at this point? I am assuming that it is a fault with the equipment in the transformer building?
I want to try to get my head around this before writing to UK power networks so I can fully understand what is going on so as to avoid getting fobbed off again.
I think you should try to keep away from technical troubleshooting and focus on the responsibilities of the supplier.
UK Power Networks have a legal and regulatory requirement to provide an electrical supply of appropriate quality. If they have documented evidence that your supply voltage is going out of spec they should be on the hook to take action.
When you write to them, you should remind them of the facts, provide evidence of costs you have incurred from damaged equipment, and insist they do something about it.
If you get no satisfaction you should take the problem to the regulator (Ofgem?)
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The fault is most likely somewhere in the grid outside your installation. By being outside your installation its the distribution company responsible to fix the problem. Depending a bit on the local legislation it might also be the distribution company that would have to pay for any damages to your installation/equipment caused by high or low voltage. In case of damages you should have the damages verified and documented by an intendant electrical engineer or electrician to claim replacement or repair.
Do also have a word with your neighbors if they got the same problems as you got. This can make a record to the distribution company that this is not just a single case.
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I am just trying to make sure I have done everything in my power so that I can prove it is not me at fault.
Annoyingly every time I phone UK Power Networks they just fob me off and say they will send an electrician but it will cost me £60. When I disagree they hang up.
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I am just trying to make sure I have done everything in my power so that I can prove it is not me at fault.
As I mentioned earlier - try measuring/logging the voltage between the incoming neutral and a "real" earth from a rod or buried pipe/metalwork. Any significant voltage would be evidence of an upstream neutral fault
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I am just trying to make sure I have done everything in my power so that I can prove it is not me at fault. Annoyingly every time I phone UK Power Networks they just fob me off and say they will send an electrician but it will cost me £60. When I disagree they hang up.
You fight against a monopolist, good luck. Had these been rotten groceries, you'd have already found a suitable solution, without any complaints to the seller.
I'd collect data proving they breached the contract and that they new about the issue and ignored it and then take legal actions. This is not only about some UPSes but they are putting your life at risk. It really does not matter if that is 254V or 300V. In the meantime, use autotransformer for critical loads.
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I am just trying to make sure I have done everything in my power so that I can prove it is not me at fault.
As I mentioned earlier - try measuring/logging the voltage between the incoming neutral and a "real" earth from a rod or buried pipe/metalwork. Any significant voltage would be evidence of an upstream neutral fault
That is a good idea! I may try that. The more evidence I can get the better.
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I am just trying to make sure I have done everything in my power so that I can prove it is not me at fault.
As I mentioned earlier - try measuring/logging the voltage between the incoming neutral and a "real" earth from a rod or buried pipe/metalwork. Any significant voltage would be evidence of an upstream neutral fault
That is a good idea! I may try that. The more evidence I can get the better.
OK so I took a log of the voltage between a big metal pipe in the ground outside and my neutral from the socket closest to the distribution panel.
Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
When the electrician came round to inspect my meter and it's connections before, I watched him, after he completed his testing, re-connect the output wires from the meter which go to my distribution board, and also he checked the input terminal bolts too. He, in my opinion did this 100% correctly and I am confident that the connections in the meter are good.
I have personally checked that every single connection in my distribution board is done up tight and also in every socket, switch and fused spur in the whole house. So I am 100% that I have no bad neutral (or live or earth for that matter) in the house.
So now I will go to them first thing Monday and badger them as much as possible to try to get an electrical engineer sent out and I am thinking of requesting another volt meter recorder in the meter cabinet.
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Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
This is nothing unexpected, that is how TN earthing works.
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Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
This is nothing unexpected, that is how TN earthing works.
I don't know the standard, but I would think a 13 volt drop in the neutral is excessive. That's >5% of the total power being dissipated if the load is fully on one phase! If this high a loss is occurring with a load that is even partly balanced on the three phases that is pretty insane. No?
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Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
This is nothing unexpected, that is how TN earthing works.
I don't know the standard, but I would think a 13 volt drop in the neutral is excessive. That's >5% of the total power being dissipated if the load is fully on one phase! If this high a loss is occurring with a load that is even partly balanced on the three phases that is pretty insane. No?
Assuming the ground at the house is at the same potential as the ground at the transformer. The ground not being a superconductor..
Correlation with excessive phase voltage would be more definitive. 13V doesn't sound amazing, though.
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Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
This is nothing unexpected, that is how TN earthing works.
I don't know the standard, but I would think a 13 volt drop in the neutral is excessive. That's >5% of the total power being dissipated if the load is fully on one phase! If this high a loss is occurring with a load that is even partly balanced on the three phases that is pretty insane. No?
Assuming the ground at the house is at the same potential as the ground at the transformer. The ground not being a superconductor..
Correlation with excessive phase voltage would be more definitive. 13V doesn't sound amazing, though.
I don't get your reasoning. Even if the impedance between the two grounds is significant, there should be virtually no current, so no voltage drop. The only way there would be voltage between the grounds is if there were enough current in the neutral to push current through the grounds as well as they are connected to the same points. So regardless, one way or the other there is excessive impedance in the neutral. You did notice that he said, "between 1 and 13V", right?
Consider if the neutral is supporting "between 1 and 13V" that means at some point there is nearly no voltage and nearly no current, then 13 times as much voltage and current. Yeah, something is messed up and it needs to be fixed.
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there should be virtually no current
I dare you to test that theory anywhere near train tracks.
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Why no current in neutral? There are only single phase loads there and the assumption about balanced load is optimistic. For the purpose of diagnosing a fault you have to consider worst case and accept the fact that whatever amps distribution company sold, can be technically pushed through neutral*. Only then an observation out of bounds indicates a fault.
Additionally, according to IEC 60364-4-43 neutral can be installed with half of the cross section of phase conductor (when some additional requirements are met). I do not know british standards regarding conductor protection but lets assume this is the arrangement that is installed. At full balanced resistive load there is ~0V drop in neutral and 253-207V=46V drop on each phase, this is still not a fault but legitimate practice of setting transformer on last tap when thin cables are installed. Had you switched off load on one phase now, the neutral current is going to equal the disconnected phase current due to Kirchoffs law but the voltage drop in neutral raises to twice the phase drop due to thinner neutral cable. Still this is not unexpected but would result in "Constant High Mains Voltages At Home" topic. So IMHO only after you exceed 253V + 2*46V=345V 253V+46V*sqrt3/2=293V you can look for faults in wiring.
If a neighbor has 6.5V drop on phase conductor and 13V on a neutral conductor, this is not a miracle, just Ohm's law.
*Actually, even IN=3xIL is still not a miracle or a fault, just odd tripplens but lets not overdo with pesimism with this analysis.
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If a neighbor has 6.5V drop on phase conductor and 13V on a neutral conductor, this is not a miracle, just Ohm's law.
*Actually, even IN=3xIL is still not a miracle or a fault, just odd tripplens but lets not overdo with pesimism with this analysis.
If you see 6.5V drop on the "hot" wire and 13V drop on the neutral, that's >7.5% of the power lost in the conductor. No utility is going to be so frugal with the conductor as to waste that much power in wiring losses from the transformer to the home unless the meter is at the transformer. What you are describing is a fault in the line.
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It is certainly possible to see 7.5% power loss between the distribution transformer and the house.
It's certainly not very common, and definitely not the design goal, but things like this happen for example when the wiring is old and the consumption has increased beyond what was originally considered. New customers, or customers transitioning from gas/oil to electric heating are typical culprits.
Fixing the thing is much more costly than losing 7.5% of the energy, especially if everybody operates on quarter years and not quarter centuries.
The biggest problem isn't the loss itself, but the voltage instability as described.
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The Ze (External Impedance) of our local electricity supply is stated to be "0.35 ohms typical maximum for TNC-S system", our house is 0.1R (measured).
From there you can apply ohms law to get the efficiency.
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(..)that's >7.5% of the power lost in the conductor. No utility is going to be so frugal with the conductor as to waste that much power in wiring losses from the transformer to the home unless the meter is at the transformer. What you are describing is a fault in the line.
Your interpretation of "fault in the line" is quite wide.
I must assure you that no efforts in fixing terminations, calling sparkys or even electrical engineers are going to help OP in fixing such "fault in the line". That is because distribution company is well aware of ohms law and the consequences of selling amps beyond reason, switching taps, all without conductor upgrade.
As for being frugal - why would a monopolyst care about electrical energy loss? There is no such term in their dictionary, this just raises distribution costs and they list that on your bill. By definition.
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Yes, I have suspected that there is an issue that they know about which they are not willing to fix. I live in a small village, well now it is technically a town. They have built several housing estates here over the last 5 years and I suspect that the wiring to our town is just not 'big' enough to cope.
New housing estates of any significant size will have new distribution transformers. If the new estates are to blame then it's a HV problem that will be affecting a wider area.
As I said, a small town, we about 3 miles from the 'big' town.
We have underground distribution.
I am less than 1 mile from the transformer.
I am not sure if it has 2 or 3 HV bushings or of the condition of the transformer as I have never seen it, it is in a small brick out building at the end of the street.
My earthing system is TNCS: so no rod.
1 mile would be a very long way, typically you would expect to be within 200 m or so. In a town, with underground distribution etc. it is almost certainly three phase unless you live in a very old area where ex-DC cables might be 3 core. With TNC-S I would expect UKPN to be very hot on neutral resistance as it is a serious safety issue.
I highly suspect that they are setting the voltage higher to cope for the increased load from the new build estates. Although this is just suspicion and I have nothing to prove this.
This is possible, but that would have to be high voltage on the HV side as they will (probably) not share an LV transformer with you. For reference, the 11 kV HV supply (everyone in the industry calls this MV but the term is deprecated) is quasi-regulated with automatic tap changing at the primary substation. The LV transformers have selectable taps but these can only be changed manually on site and in most cases they are set to 250 V and only changed if there are problems.
OK so I took a log of the voltage between a big metal pipe in the ground outside and my neutral from the socket closest to the distribution panel.
Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
This voltage range is totally normal on TNC-S. What you really need to do is record this voltage when the mains voltage is out of spec (but carefully, because the voltage between your TNC-S earth and the pipe might be large enough to be hazardous). If the voltage to true earth is much higher under that condition then that's strong evidence for a bad neutral between you and the substation. If it's still in this range then the problem lies elsewhere.
If you never see less than 245 V it might be you are very close to the transformer, and they are unwilling to change down a tap because someone else far away would go out of spec at the bottom end. However, the voltages you are seeing are too high to be explained by the transformer being on the 250 V tap, the 315 V for definite, 270 V is stretching plausibility a little. The transformer is normally rated for 5% drop at full load (about 2/3 of this is inductive), so a tap for 250 V at full load would be expected to be no higher than 263 V with zero load. I mean maybe, if there's almost no load on your phase so that would be 263 V, and heavy load on the other phases pulling the neutral away from you, that could get to 270 V, but the 315 V can only be a fault.
In any case UKPN are in breach of their statutory obligations once it goes beyond 253 V and inaction after clear evidence surprises me somewhat.
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As for being frugal - why would a monopolyst care about electrical energy loss? There is no such term in their dictionary, this just raises distribution costs and they list that on your bill. By definition.
This. Even if the meter is on the customer's house and hence the wasted energy isn't billed directly, it's the customer who eventually pays for the whole shebang.
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As for being frugal - why would a monopolyst care about electrical energy loss? There is no such term in their dictionary, this just raises distribution costs and they list that on your bill. By definition.
This. Even if the meter is on the customer's house and hence the wasted energy isn't billed directly, it's the customer who eventually pays for the whole shebang.
I don't know how they are managed in the UK, but in the US utilities are required to get their rates approved. That only happens every so often so in the mean time the way to higher profits are to reduce costs. Wasted power in distribution is a cost. So like nearly every company, costs and waste are minimized.
What utilities are not encouraged to do is minimize capital investment. In fact, the profits are often normalized to capital investment, so greater investment allows higher profits at rate setting time.
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Hi. Thanks for getting back to me.
Yes, I have suspected that there is an issue that they know about which they are not willing to fix. I live in a small village, well now it is technically a town. They have built several housing estates here over the last 5 years and I suspect that the wiring to our town is just not 'big' enough to cope.
New housing estates of any significant size will have new distribution transformers. If the new estates are to blame then it's a HV problem that will be affecting a wider area.
My street was built in 1995 at the time time the transformer was fitted. There are a fair few transformers in this 'older' part of the estate but in the new areas I have yet to find and transformers. Unless they are underground I think they are just tapping off the existing ones.
As I said, a small town, we about 3 miles from the 'big' town.
We have underground distribution.
I am less than 1 mile from the transformer.
I am not sure if it has 2 or 3 HV bushings or of the condition of the transformer as I have never seen it, it is in a small brick out building at the end of the street.
My earthing system is TNCS: so no rod.
1 mile would be a very long way, typically you would expect to be within 200 m or so. In a town, with underground distribution etc. it is almost certainly three phase unless you live in a very old area where ex-DC cables might be 3 core. With TNC-S I would expect UKPN to be very hot on neutral resistance as it is a serious safety issue.
I would gues it is around 200m. It is literally at the entranc eto our cul-de-sac and there is about 12 house on my side of the street between me and the transformer. The UKPN electrician said I am the last house on this phase.
I have already highlighted this as a safety issue to them on the phone and they just threaten to come and cut off my electricity immediately and will not forward my call further.
I highly suspect that they are setting the voltage higher to cope for the increased load from the new build estates. Although this is just suspicion and I have nothing to prove this.
This is possible, but that would have to be high voltage on the HV side as they will (probably) not share an LV transformer with you. For reference, the 11 kV HV supply (everyone in the industry calls this MV but the term is deprecated) is quasi-regulated with automatic tap changing at the primary substation. The LV transformers have selectable taps but these can only be changed manually on site and in most cases they are set to 250 V and only changed if there are problems.
The UKPN electrician said our tap is set to 249V at the transformer.
OK so I took a log of the voltage between a big metal pipe in the ground outside and my neutral from the socket closest to the distribution panel.
Over the course of today it varies randomly every few seconds between 1 and 13V!!! So I think we have found a clue.
This voltage range is totally normal on TNC-S. What you really need to do is record this voltage when the mains voltage is out of spec (but carefully, because the voltage between your TNC-S earth and the pipe might be large enough to be hazardous). If the voltage to true earth is much higher under that condition then that's strong evidence for a bad neutral between you and the substation. If it's still in this range then the problem lies elsewhere.
Surely this would have shown in their readings?
The 1-13V reading is between the 'real earth' and neutral. I am not getting these readings between the plug socket earth and neutral. It is always less than 0.1V there.
If you never see less than 245 V it might be you are very close to the transformer, and they are unwilling to change down a tap because someone else far away would go out of spec at the bottom end. However, the voltages you are seeing are too high to be explained by the transformer being on the 250 V tap, the 315 V for definite, 270 V is stretching plausibility a little. The transformer is normally rated for 5% drop at full load (about 2/3 of this is inductive), so a tap for 250 V at full load would be expected to be no higher than 263 V with zero load. I mean maybe, if there's almost no load on your phase so that would be 263 V, and heavy load on the other phases pulling the neutral away from you, that could get to 270 V, but the 315 V can only be a fault.
In any case UKPN are in breach of their statutory obligations once it goes beyond 253 V and inaction after clear evidence surprises me somewhat.
Again they said I am the last house on this phase, so surely this would mean all the nearer houses are getting higher voltages than me and I am the highest.
Went for a walk today and 2 of my neighbours further up the road have old fridges on the pavement. I expect blown up from the high voltage.
Often at night, usually about 1-3am (it varies exactly when) the mains voltage will jump suddenly from around 255 to approx 262V for around 5-20 minutes, then suddenly drop down again to around 254/255V. But never in the daytime, today it has been 246 - 252 so far (now 3pm). Some nights it doesn't do it, but I would say around 85% of the time it does.
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I have found a copy of the voltage readings from when I first reported the issue. These were the readings UKPN sent me after they removed their volt meter from the cabinet. I have not heard from them since!
Also attached is the letter I received.
I have redacted personal details if you are wondering about the big black smudges :)
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I have already highlighted this as a safety issue to them on the phone and they just threaten to come and cut off my electricity immediately and will not forward my call further.
They can't do that.
Report this behaviour along with copies of the letter and plots given to you by UKPN to the Energy Ombudsman: https://www.ombudsman-services.org/ (https://www.ombudsman-services.org/)
E: It seems UKPN don't deal with the Ombudsman. They're also Chinese owned, this somehow doesn't surprise me. I would still give the Ombudsman a call, if they can't help you, call Citizens Advice, if they can't, call Ofgem. Normally Ofgem don't get involved in consumer disputes but they're the last port of call and ultimate authority.
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Again they said I am the last house on this phase, so surely this would mean all the nearer houses are getting higher voltages than me and I am the highest.
It seems you do not understand three phase supply.
Since you are the last one, you are going to experience the highest voltage across neutral (or should I say PEN as this is TN-C-S). This neutral voltage might come from the load on:
- only your-phase (you experience voltage drop in socket) or
- only not-your-phases (you experience voltage raise in socket)
- or some other combination of loads where the end result is more convoluted.
The point here is that neutral is shared between all of your neighbours. Had you been connected next to transformer, there would have been no problems with overvoltage. IMHO.
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Their voltage readings are much lower than the worst case you've observed, but still clearly out of spec. I wouldn't bother phoning them, it's pretty useless, and I wouldn't accept any phone calls either, insist on having everything in writing.
I would write directly to the Supply Quality Manager whose name and address you have, reference the letter, their previous acceptance that the supply is out of tolerance, your continued problems, etc. Give them a reasonable but clear deadline, say 4 weeks, and state that you will be in contact with the ombudsman if you don't receive a reasonable response in that timeframe. They will probably ignore it or send you some standard template letter, but that's fine, this is all good evidence. A recent letter and evidence of recent inaction will be helpful in getting the ombudsman on side.
Unfortunately the ombudsman is probably more used to dealing with complaints about money, payment to metering operators, etc. and may not be too familiar with technical supply-quality complaints. Still your best route though.
Again they said I am the last house on this phase, so surely this would mean all the nearer houses are getting higher voltages than me and I am the highest.
It seems you do not understand three phase supply.
Since you are the last one, you are going to experience the highest voltage across neutral (or should I say PEN as this is TN-C-S). This neutral voltage might come from the load on:
- only your-phase (you experience voltage drop in socket) or
- only not-your-phases (you experience voltage raise in socket)
- or some other combination of loads where the end result is more convoluted.
The point here is that neutral is shared between all of your neighbours. Had you been connected next to transformer, there would have been no problems with overvoltage. IMHO.
Put another way, being far away is bad because both line and neutral voltage are more variable and with the particular combinations of loads on your street this variation results in your seeing high voltages. Typically, your line voltage may be lower than near the transformer (relative to N at the substation) but almost certainly your neutral voltage is a long way from zero (again relative to the substation N). In your case the neutral voltage is perhaps a few tens of Volts, but opposite in phase to your line voltage because the neutral is being pulled away from zero by loads on other phases, that increases the L-N voltage you observe.
The most recent information you've given suggests that you probably have a full-sized neutral (based on the date) but that your phase is very lightly loaded whilst the others are heavily loaded at night and without any large loads on your phase this results in the long, relatively high resistance neutral being pulled away from your phase towards the other two. Maybe there's simply an unlucky combination of loads and it just happens that most of the houses on your phase are unoccupied, gas-heated, etc. and most of the houses on the other two phases are heavy night-time users with storage heaters. Statistically this has to happen occasionally. Or maybe the cable jointers screwed up and you are the only house on your phase.
It would be possible to make some further measurements that might help confirm what's happening, but it's not especially useful, it's UKPN's problem to fix.
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seeing the drop on your voltage is a few volt when consuming 20A, that looks like a pretty normal source impedance here.
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seeing the drop on your voltage is a few volt when consuming 20A, that looks like a pretty normal source impedance here.
I'm not sure what voltages you are saying are ok. I've measured the voltages at my house when the water heater was drawing about 18 amps and it was still spot on. The run to the transformer is not far of course. I guess that's the part I don't get, the use of such long runs of low voltage cables. In the US they typically limit the runs to a few hundred feet (approx 100 m) other than seriously rural runs that were put in 50 years ago.
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The (very small) drop of voltage when suddently switching on 20A of load gives a hint on the short term source impedance.
Here it seems OK, so as a consequence, the neutral seems not to have a high impedance in itself -> no loose connection close by.
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In the US they typically limit the runs to a few hundred feet (approx 100 m) other than seriously rural runs that were put in 50 years ago.
This is consistent, most US installs would be split phase so around 240 V L-L, UK installs would be 3 phase over most of that distance so 400 V L-L, the voltage is sqrt(3) higher, the impedance is 3x higher, so you can go 3x the distance for the same power loss.
A very typical suburban setup in the UK would be a 500 kVA, three-phase, delta-star transformer from 11 kV to 400 V, feeding perhaps ten outgoing three-phase cables fused at around ~400 A, each with numerous branches to feed single or three phase customers. There would usually be linkboxes under the pavement allowing interconnection of different LV cables from the same or different substations. This is quite different from the usual US approach with numerous small transformers.
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In the US they typically limit the runs to a few hundred feet (approx 100 m) other than seriously rural runs that were put in 50 years ago.
This is consistent, most US installs would be split phase so around 240 V L-L, UK installs would be 3 phase over most of that distance so 400 V L-L, the voltage is sqrt(3) higher, the impedance is 3x higher, so you can go 3x the distance for the same power loss.
A very typical suburban setup in the UK would be a 500 kVA, three-phase, delta-star transformer from 11 kV to 400 V, feeding perhaps ten outgoing three-phase cables fused at around ~400 A, each with numerous branches to feed single or three phase customers. There would usually be linkboxes under the pavement allowing interconnection of different LV cables from the same or different substations. This is quite different from the usual US approach with numerous small transformers.
Your analysis seems to be mistaken. You are claiming the UK line voltage is higher so the current is smaller, etc, but your math is faulty. The power to any one home is not three phase, it is one leg to the neutral. So the current drawn for a given load is the same ~240V as in the US. The voltage between the phases is irrelevant for the feed from the transformer to the home. You seem to be talking about the higher voltage lines which are three phase in the US as well.
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When talking about distance from the substation, surely the cable size is also an important factor? If there is going to be a big substation serving many homes over a wider area, maybe the cables are bigger?
Also maybe the cables in typical UK installations are copper? Whereas my service in the USA is delivered on aluminum cables.
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If it was installed in 1992 it definitely is an aluminium core cable, as the 1970's copper price spikes made aluminium cables the dominant cable in all new installations, and the utilities now are actively swapping out older bare copper lines to ABC runs, with the price they get for the scrap copper covering the cost of the new cable and installation.
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Your analysis seems to be mistaken. You are claiming the UK line voltage is higher so the current is smaller, etc, but your math is faulty. The power to any one home is not three phase, it is one leg to the neutral. So the current drawn for a given load is the same ~240V as in the US. The voltage between the phases is irrelevant for the feed from the transformer to the home. You seem to be talking about the higher voltage lines which are three phase in the US as well.
The cable from a typical US transformer to a home is 240 V split phase (with the transformer feeding only one or two properties). The cable from a typical UK transformer to a home is 400 V 3 phase for the majority of it's length, perhaps 180 m of a 200 m run, and then single phase for the last 20m or so. As we were discussing the losses in the length of the cable all the way back to the transformer it is absolutely relevant to consider that most of its length is three phase when talking about power delivery to its many single phase loads. Consider for example that under typical loading (but not unfortunately in Paul's case) the neutral currents from many properties cancel reasonably well and the neutral current ends up being small compared to the phase currents (20-50% is not atypical, and losses go as the square) so in the context of of analysing the losses the 180m of cable from the substation it might as well be feeding a 400 V delta load. Yes the loads are really star and there is some neutral current, but the dominant losses in the 3 phase section are in the phase conductors.
Put another way, from the perspective of one of the single phase customers, the neutral has minimal voltage drop (because their neutral current is mostly returned by other nearby customers to the other two live conductors) and they only observe voltage drop / power loss on the live pole of the supply. In a three-phase cable with many single phase loads at the far end or distributed along it the losses, to a reasonable approximation, are those you would get with a 3 phase 400 V load. This is the same reasoning as treating the US setup as 240 V rather than 120 V despite the presence of 120 V loads.
To be honest it was largely a flippant remark about the cables being longer because the effective voltage is higher (though the voltage delivered to the end user is not). A full analysis would of course take account of cable sizes, the fact that the UK setup has a greater number of conductors which is copper that could otherwise be used to reduce losses in a split phase setup, etc.
As Sean says for a 90s install it will probably be Aluminium. I think they were using WaveCon by then so 3 triangular aluminium cores surrounded by a wave-wound (not spiralled) bundle of copper wires that form the CNE conductor. 240 mm2 is a common size. The branch to the house will probably be concentric with a 35 mm2 aluminium live surrounded by 25 mm2 of copper strands. This has the nice feature that if you put a spade through it the aluminium tends to burn back up the middle until the arc is extinguished, if you're lucky before the substation fuse blows.
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I remember in primary school, around 1975, they were doing a whole load of cable work right outside the school, and there were lots of little sawn off sections of the aluminium cable there. 4 triangularish conductors, with a coloured PVC sheath, and then that in turn surrounded with a black plastic sheath, and then the steel wire armouring wires around that, and the final protective sheath, with the cable being run along the street in a newly dug trench from the transformer, to a new block of flats being built in the cul de sac at the end of the road. Took some of those little pieces home with me.
Now only ABC cable, as it is faster and cheaper to install, though the quality of the work often leaves a lot to be desired, though it is still stolen on a regular basis.
I am at the moment on the end of 200m of cable, though the substation is 60m away, as it runs in a dog leg, and yes, I have had a few mains voltage excursions that reached nearly 300VAC, which was when the thieves broke in to the substation and removed the neutral and earthing from there, and cut back the armour on the cables, century old, so just unwind the steel strap to expose the paper, and cut the neutral off of the cable for 10m. The load was reasonably constant, so the excursions on the mains were small, till the coffee shop turned on their oven to bake the morning load, and this dragged the one phase down to 160VAC, and the others rose up in sympathy. I had a UPS high voltage warning, measured the mains, and turned off all power at the board, then went to the meter room, measured the phases all over the place, and turned off the building, then phoned the metro to notify them of loss of neutral.
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When talking about distance from the substation, surely the cable size is also an important factor? If there is going to be a big substation serving many homes over a wider area, maybe the cables are bigger?
Also maybe the cables in typical UK installations are copper? Whereas my service in the USA is delivered on aluminum cables.
Maybe they do things differently in the UK, but in the US a substation feeds many, many homes, like many blocks of homes. The substation outputs a high voltage which is dropped to 240 V by a distribution transformer to feed the homes.
There's nothing wrong with aluminum wire. They make the cross section larger to account for the higher resistivity resulting in the same resistance and the same losses. They don't use it in homes anymore because it was not installed properly in the 70's causing fires. They can use it safely, but like any other technology it has to be done correctly.
Actually, I've been told in the UK older installations were done with aluminum sleeves for the earth ground. Something wasn't done correctly and the rather thin aluminum sleeve corroded away leaving entire blocks with no safety ground. Expensive to correct.
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Actually, I've been told in the UK older installations were done with aluminum sleeves for the earth ground. Something wasn't done correctly and the rather thin aluminum sleeve corroded away leaving entire blocks with no safety ground. Expensive to correct.
Chances are that the homes have their own grounding anyway. At least that is standard in NL.
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Maybe they do things differently in the UK, but in the US a substation feeds many, many homes, like many blocks of homes. The substation outputs a high voltage which is dropped to 240 V by a distribution transformer to feed the homes.
Ah, it's a terminology issue, I understand now. In the UK we would call what you refer to as a "substation" a "primary substation", in the UK this usually outputs 11 kV line to line. These cover quite wide areas, a mid sized town might have one only, a city of a million people might have half a dozen. The substations Ian and I were referring to are more akin to your distribution transformers, we would normally call a ground-mounted distribution transformer and its associated switchgear, etc. a "substation". Our distribution transformers often serve hundreds of customers within a few hundred metres.
Actually, I've been told in the UK older installations were done with aluminum sleeves for the earth ground. Something wasn't done correctly and the rather thin aluminum sleeve corroded away leaving entire blocks with no safety ground. Expensive to correct.
There was a short period between the demise of PILC cables and the rise of polymeric ones when cables with aluminium sheaths were attempted (cheaper than lead I guess?). It turned out to be a rather bad idea.
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Maybe they do things differently in the UK, but in the US a substation feeds many, many homes, like many blocks of homes. The substation outputs a high voltage which is dropped to 240 V by a distribution transformer to feed the homes.
Ah, it's a terminology issue, I understand now. In the UK we would call what you refer to as a "substation" a "primary substation", in the UK this usually outputs 11 kV line to line. These cover quite wide areas, a mid sized town might have one only, a city of a million people might have half a dozen. The substations Ian and I were referring to are more akin to your distribution transformers, we would normally call a ground-mounted distribution transformer and its associated switchgear, etc. a "substation". Our distribution transformers often serve hundreds of customers within a few hundred metres.
Those numbers don't seem to add up. Hundreds of customers within a few hundred meters means people are practically standing on top of one another. If all these customers are fed in a single run the current in the first leg would be huge!
Actually, I've been told in the UK older installations were done with aluminum sleeves for the earth ground. Something wasn't done correctly and the rather thin aluminum sleeve corroded away leaving entire blocks with no safety ground. Expensive to correct.
There was a short period between the demise of PILC cables and the rise of polymeric ones when cables with aluminium sheaths were attempted (cheaper than lead I guess?). It turned out to be a rather bad idea.
Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
I was interested in ham antennas at one time and found there is a type of tubing with plastic inside and out, but aluminum in the sandwich to act as an oxygen barrier. This prevents rust formation and other oxidation in heating systems. If you protect the aluminum from everything else it is not a bad component in a cable or pipe, but on the outside it is a very bad idea.
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Actually, I've been told in the UK older installations were done with aluminum sleeves for the earth ground. Something wasn't done correctly and the rather thin aluminum sleeve corroded away leaving entire blocks with no safety ground. Expensive to correct.
Chances are that the homes have their own grounding anyway. At least that is standard in NL.
I was discussing grounding in a UK ham group and they made the point that many homes simply can not obtain an adequate ground locally. Practice is to bond the ground wire to everything metal that could be grounded, like plumbing, so if there is an open protective earth/neutral (PEN) there won't be a voltage differential. If the ground is poor, everything in the home is at the same high voltage.
This falls apart when power is used outside the home. I don't know how they manage that situation. I'm sure I heard about it, but I don't recall the details. Maybe that would be handled by an RCD/GFCI device since at that point the current in the circuit is not balanced.
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This falls apart when power is used outside the home. I don't know how they manage that situation.
By following the relevant part of the wiring regulations that don't permit the cpc to be exported outside the equipotential zone if a TNC-S supply method is used. What you do is convert the outside circuits to TT (use an earth spike) so only live and neutral are taken outside
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Those numbers don't seem to add up. Hundreds of customers within a few hundred meters means people are practically standing on top of one another. If all these customers are fed in a single run the current in the first leg would be huge!
A few hundred customers within a few hundred metres radius, not all on the same cable. Commonly 5-10 cables might radiate out in different directions, each 100-200 m long in an urban area, longer in a rural area. A 200 m radius is 120,000 m2, a typical suburban UK property is maybe 200 m2 (land area not building area), 120,000/200 = 600.
But yes the currents can be fairly high, a 1 MVA transformer is around 1300 A per phase, but that's on the larger end.
Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Yup, lead. A good search term is "PILC cable" - Paper Insulated Lead Covered. Lots of photos covering a range of construction types and voltages here:
https://www.spenergynetworks.co.uk/userfiles/file/scottishpower_cables_equipment_metal_theft.pdf (https://www.spenergynetworks.co.uk/userfiles/file/scottishpower_cables_equipment_metal_theft.pdf)
LV PILC on page 18, note the undersized neutral on one of the examples.
Long ago (1930s) we also had lead covered rubber cables like this in domestic use:
https://img1.wsimg.com/isteam/ip/14f7f3aa-bbda-4bcf-bf19-2ab202e8e95c/81a326a6-24ce-4b6d-ae58-460e8af5ce60.jpg/:/rs=w:1280 (https://img1.wsimg.com/isteam/ip/14f7f3aa-bbda-4bcf-bf19-2ab202e8e95c/81a326a6-24ce-4b6d-ae58-460e8af5ce60.jpg/:/rs=w:1280)
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Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Before plastic, cables for wet environments were encapsulated in extruded lead.
Here is a great article from 1931 about how they did that for telephone cables: https://archive.org/details/bstj10-3-432/mode/2up
Lead has also been used as conductor, but almost only for very high currents, where the "cable" were more or less cast in place, where it would be needed, for instance the main busbar in the first generation of power-plants.
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Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Most houses built in the 1930s and 1940s, at least in the UK, used rubber insulated tinned copper wire with an overall lead sheath. The tinning was needed to limit the reaction between copper and rubber. In the 1950s the price of lead skyrocketed, as the nuclear industries took off, and early plastics, like PVC, had been around long enough to see that they were pretty stable long term. The industry moved to plastic insulated and sheathed cable. By the 1960s most of the rubber was rotting, so by the late 1970s most of this lead sheathed cabled had been ripped out and replaced.
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Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Before plastic, cables for wet environments were encapsulated in extruded lead.
My incoming supply is on lead cables (mid- 1960s) [attachimg=1]
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Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Yup. And only old-timer electricians have the skills to deal with these cables. Soldering a ground wire onto the lead shield using a blowtorch is a bit of an art. One of my relatives used to be an electrician. IIRC they still called him when they needed someone to deal with a lead clad cable after he retired.
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This falls apart when power is used outside the home. I don't know how they manage that situation.
By following the relevant part of the wiring regulations that don't permit the cpc to be exported outside the equipotential zone if a TNC-S supply method is used. What you do is convert the outside circuits to TT (use an earth spike) so only live and neutral are taken outside
So when you are using a hand power tool you add an earth spike to your extension cord?
That was how the conversation went with a description of all manner of messy, complicated and potentially unworkable approaches. It also doesn't protect against any number of innocuous situations where the "equipotential zone" is violated. Off the top of my head someone might have a clothesline strung from the house to a metal pole that can be reached from a window. These are not so rare. If the line has metal in it and the plastic cover degrades, there is a potential of a ground point that is reached through the window while in contact with the laundry equipment.
Obviously these things are rare or they would have been factored into the standard. I've just never understood why it is so important to minimize the cost of running proper ground wires and sharing the neutral. That simply isn't done in the US. I can see the aluminum ground wire in the cable that runs to my house. It stands out clearly against the insulated current carrying wires.
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Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Before plastic, cables for wet environments were encapsulated in extruded lead.
My incoming supply is on lead cables (mid- 1960s) (Attachment Link)
Looks like that cable has paint on it. I hope it isn't leaded paint. They might have to rip that out to get rid of the paint!
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Lead??? I've never heard of using lead in electric cables. I guess there's a first time for everything.
Before plastic, cables for wet environments were encapsulated in extruded lead.
My incoming supply is on lead cables (mid- 1960s) (Attachment Link)
Most houses in the UK are like that. The insulation in those underground cables didn't degrade like the rubber insulation used for the lead sheathed wiring inside the house, so there has never been a need to replace the underground stuff. 100 year old cables are basically as good as new, and only need replacing if a higher rating is needed.
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So when you are using a hand power tool you add an earth spike to your extension cord?
We sidestep the problem by having product standards that mandate equipment for outdoor use (power tools, lawnmowers, etc.) is Class II double insulated, not requiring an earth. This falls over a bit for non-domestic things like welders, and for things like electric cars where they should probably have been Class II but aren't.
Obviously these things are rare or they would have been factored into the standard. I've just never understood why it is so important to minimize the cost of running proper ground wires and sharing the neutral. That simply isn't done in the US. I can see the aluminum ground wire in the cable that runs to my house. It stands out clearly against the insulated current carrying wires.
Mostly, it's a cheap-arse 1970s bodge that was supposed to save money, and one which is looking increasing dubious in the modern world. That said, it has some advantages; open-circuit PEN conductors are very noticeable and therefore quickly repaired in comparison to rarely-use earth conductors, the low fault impedance gives fast disconnection during a fault, etc.
If we were designing a system from scratch, I would favour an impedance-earthed transformer star point, say about an Ohm. It would limit earth fault current to a few hundred amps, so earth could be distributed cheaply on smallish (say 25 mm2 copper cabling, but such a current is plenty large enough to reliably trip an RCD(GFCI)-like device without needing carefully balanced mechanics with low reliability like lower value RCDs have. That said if we were designing from scratch I'd push the distribution voltage up as well. Single phase domestic supplies are also clearly a UK mistake.
Actually, electrical deaths are remarkably low, especially shock deaths (as opposed to fire, etc.) so it doesn't actually make sense to spend a load of money to reduce shock risk when investing that same amount in road safety, anti smoking campaigns or healthcare would save more lives. In fact I suspect that in the big picture many electrical safety things are barely justified.
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We sidestep the problem by having product standards that mandate equipment for outdoor use (power tools, lawnmowers, etc.) is Class II double insulated, not requiring an earth. This falls over a bit for non-domestic things like welders, and for things like electric cars where they should probably have been Class II but aren't.
Would be nice if EVs were class II, but would be pretty tricky to make an 11 or 22kW onboard charger that passes EMC without a ground connection!
I suppose a double-insulated barrier between the mains and DC side, and also between the AC and body might be possible, but it's too late now.
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We sidestep the problem by having product standards that mandate equipment for outdoor use (power tools, lawnmowers, etc.) is Class II double insulated, not requiring an earth. This falls over a bit for non-domestic things like welders, and for things like electric cars where they should probably have been Class II but aren't.
Would be nice if EVs were class II, but would be pretty tricky to make an 11 or 22kW onboard charger that passes EMC without a ground connection!
I suppose a double-insulated barrier between the mains and DC side, and also between the AC and body might be possible, but it's too late now.
A functional earth for EMC-only, not connected to the chassis would be fine. Isolation mains to battery is likely to add a lot of cost and weight, easier to let the battery wiring flap around at mains live and double insulate that. The main problem there is that you can't really manage to meet double insulation in the motor windings as it adds significant volume, so they would need to be isolated during charging with a contactor that achieves a suitable gap. This then precludes Zoe-like charging where the main inverter is used as the charger with the motor as the inductors.
I can see why cars are Class I, but that doesn't mean I have to like it. I can also see arguments that PE should be safe to bolt to random bits of outdoor metal and therefore that the fault lies with TNC-S not the cars.
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That simply isn't done in the US. I can see the aluminum ground wire in the cable that runs to my house. It stands out clearly against the insulated current carrying wires.
That is your neutral.
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If we were designing a system from scratch, I would favour an impedance-earthed transformer star point, say about an Ohm. It would limit earth fault current to a few hundred amps, so earth could be distributed cheaply on smallish (say 25 mm2 copper cabling,(..)
I'd say that for residential, TN-S earthing is rare as hen's teeth and is the only one that distributes PE. Second popular is TT but does not distribute PE at all. So the applicability of this invention would have been quite narrow. Don't you think that a failure of single RCD could put whole neighbourhood in danger with this 1 \$\Omega\$?
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If we were designing a system from scratch, I would favour an impedance-earthed transformer star point, say about an Ohm. It would limit earth fault current to a few hundred amps, [...]
That is called a "Petersen Coil" or "Arc Supression Coil" and have been in widespread use in Europe for 104 years.
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If we were designing a system from scratch, I would favour an impedance-earthed transformer star point, say about an Ohm. It would limit earth fault current to a few hundred amps, so earth could be distributed cheaply on smallish (say 25 mm2 copper cabling,(..)
Don't you think that a failure of single RCD could put whole neighbourhood in danger with this 1 \$\Omega\$?
I don't. How I see it working is that the supplier provides each customer a ~10 A or so rated, simple, robust, reliable differential current trip in the same assembly as they currently provide a fuse, and a second backup unit at the substation. Householders are free to and encouraged to have lower rated* RCDs to avoid nuisance tripping of their whole supply. If the device fails to open a higher rated and slower one at the substation does preventing the PE being too far from true earth for an excessive time. i.e. if the downstream device fails are larger area is off supply, but the system is still safe. It's not all that different to the current setup really.
Of course it'll never happen, too much installed infrastructure exists, and nor do I claim to have "invented" it.
*And faster, proper coordination with RCDs requires time delays.
That is called a "Petersen Coil" or "Arc Supression Coil" and have been in widespread use in Europe for 104 years.
I've not come across that naming, but yes I know it exists. I wasn't aware of anywhere that currently uses it for LV? In the UK we use such a setup on our HV distribution, all HV loads are delta connected but the source is a star winding with impedance earthing. Any imbalance current on the phases is a fault which is quickly and easily detected, but limited in energy by the impedance in the star point. This is different to American practice that tends to distribute HV Neutral (or HV CNE? I'm not sure?) with pole pigs normally connected between it and a single HV phase.
Actually reading this was an interesting read, Petersen coil's are not quite the same thing, instead of simply adding impedance (R or L) to control current to a few KA for damage reduction, they actually try to make them resonant to limit the current to just a few amps so the system can stay live. Interesting stuff. https://www.westernpower.co.uk/downloads/4102 (https://www.westernpower.co.uk/downloads/4102)
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Don't you think that a failure of single RCD could put whole neighbourhood in danger with this 1 \$\Omega\$?
I don't. How I see it working is that the supplier provides each customer a ~10 A or so rated, simple, robust, reliable differential current trip in the same assembly as they currently provide a fuse, and a second backup unit at the substation. (..) Of course it'll never happen, too much installed infrastructure exists, and nor do I claim to have "invented" it.
You are aware that current IEC regulations prohibit use of any switchgear on PE? I mean, zero. No switches, disconnectors, isolators, fuses. You would have to install sth that disconnects phases and neutral only (so you need 4-pole RCD). So the failure of this one RCD would have tripped whole area, finding nuisance tripping of this fault in a city would have been an experience very close to horror story.
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You are aware that current IEC regulations prohibit use of any switchgear on PE? I mean, zero. No switches, disconnectors, isolators, fuses. You would have to install sth that disconnects phases and neutral only (so you need 4-pole RCD). So the failure of this one RCD would have tripped whole area, finding nuisance tripping of this fault in a city would have been an experience very close to horror story.
I wasn't expecting to disconnect PE (though note it is now common for EV chargers to disconnect PE in the event of lost TNC-S neutral, yey for ugly workarounds).
In the current system the failure-to-open of a single fuse at the customer* results in a the same sized area going off supply when the fuse at the distribution substation consequently opens. Yes, fuses are more reliable than RCDs, but that in part is because most RCDs contain contain finely balanced mechanics to allow tripping from just 30 mA and this makes them susceptible to friction, corrosion, etc. A 10 A RCD should have a reliability closer to a 10 A MCB than a 30 mA RCD.
*This happens fairly often, most commonly because the customer damages the cable prior to that fuse but also due to faulty, damaged or hopelessly-obsolete (not capable of breaking modern fault current levels) fusing arrangements at the customer incomer. A distribution substation fuse blows, 30-40 customers loose supply for a couple of hours.
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[...]fusing arrangements at the customer incomer. [...]
I'm trying to understand what you're saying, and failing.
Can you tell me how UK differs from how we do it here in DK ?
At the 10kV/400V trafo, each distribution cable (4x400mm² typically) is fused with Nx100A. Those almost only blow when a backhoe does something stupid. The neutral is grounded at the trafo. No PEN in the distribution cables.
Each installation is fused at the point where it connects to the distribution cable, typically in a small road-side cabinet or at the top of a mast.
For a house 3x25A is normal. They are in peril when preparing for X-mas evening, but usually make it through.
From there it goes underground, or in a few straggling cases via overhead wire, (typically 4x4mm², but 4x16mm² for longer runs) to the house, through the meter, which is mounted on the outside of the building these days, then to the distribution panel where, it hits the HPFI first. Each building has its own PEN electrode.
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https://www.quora.com/Where-can-I-find-and-size-a-whole-house-voltage-stabilizer-We-live-in-a-developing-country-where-voltage-fluctuations-are-frequent-and-extreme-It-is-not-unusual-for-a-phase-to-disappear-altogether-220V-1-50Hz (https://www.quora.com/Where-can-I-find-and-size-a-whole-house-voltage-stabilizer-We-live-in-a-developing-country-where-voltage-fluctuations-are-frequent-and-extreme-It-is-not-unusual-for-a-phase-to-disappear-altogether-220V-1-50Hz)
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[...]fusing arrangements at the customer incomer. [...]
I'm trying to understand what you're saying, and failing.
Can you tell me how UK differs from how we do it here in DK ?
Basically that UK houses typically have high-current single phase supplies. This is not really a very good idea, but the vast majority of domestic supplies, old and new, are single phase.
A typical underground distribution cable might be 240 mm2, 3 core aluminium plus concentric PEN usually copper. Line conductors are fused at ~300 A. Each customer gets a single-phase feed which typically branches off the distribution cable somewhere under the street, this might be around 25 mm2 and is usually concentric as well. This cable runs through the customer property, often under the driveway or front garden, and ends in a "service head" which looks something like this: https://talk.electricianforum.co.uk/uploads/monthly_2016_04/570411866dc11_Servicecablehead.png.194acc5547d6d78e3f6464db9ab1b692.png (https://talk.electricianforum.co.uk/uploads/monthly_2016_04/570411866dc11_Servicecablehead.png.194acc5547d6d78e3f6464db9ab1b692.png). The service head typically contains a 60, 63, 80 or 100 A cartridge fuse in L only. This fuse is to limit let-through energy into the customer installation, as well as to protect the branch cable and the meter, etc. If TNC-S earthing is used this is where PE and N separate. Typically 25 mm2 conductors go from the service head to the meter, and then to the customer's equipment. There are variants on this, TNS and TT earthing are both fairly common, older cables may be paper insulated lead covered, old service heads containing open-wire fuses still exist but are now rare. Often the supply looks like (and originally was) TNS with a split-concentric cable or a 2 core plus sheath PILC cable but in fact some section of the street cable combines N and E making it non-obvious TNC-S. >:(
A typical L-E fault current in this setup is 2-10 kA. Usually a L-E fault in the customer installation trips MCBs in their consumer unit. More rarely such a fault, or a long duration overload, will open the 60-100 A fuse in the service head. More rarely still a fault in the consumer installation can open a substation fuse; if the substation fuse is already running hot due to heavy load, the service head fuse has been replaced with e.g. a bolt by a customer* who blew it cooking Christmas dinner, the service head has some ancient open-wire fuse that can't break the arc, or the customer simply damages the cable on their property prior to the service fuse (spade, nail, etc.).
*illegal, but it happens.
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[...]fusing arrangements at the customer incomer. [...]
I'm trying to understand what you're saying, and failing.
Can you tell me how UK differs from how we do it here in DK ?
At the 10kV/400V trafo, each distribution cable (4x400mm² typically) is fused with Nx100A. Those almost only blow when a backhoe does something stupid. The neutral is grounded at the trafo. No PEN in the distribution cables.
Each installation is fused at the point where it connects to the distribution cable, typically in a small road-side cabinet or at the top of a mast.
For a house 3x25A is normal. They are in peril when preparing for X-mas evening, but usually make it through.
From there it goes underground, or in a few straggling cases via overhead wire, (typically 4x4mm², but 4x16mm² for longer runs) to the house, through the meter, which is mounted on the outside of the building these days, then to the distribution panel where, it hits the HPFI first. Each building has its own PEN electrode.
A more up to date and hopefully more representative / clearer TNC-S installation (situated in integral garage). Although the service head and incoming supply cable date back to the early 1980s.
The 3-phase street cable is paper insulated, so presumably the individual house branches are too. Each house is connected to one phase with PEN to the outer sheath. These connections are buried underground and inaccessible. If you look at the cable boot on the feed cable entry into the service head, you can see that the cable is coaxial with the PEN conductor forming the outer sheath. You can also see a Yellow disc on the back board, signifying that the house is on the Yellow phase of the street cable (old colour coding).
As richard.cs says, the service head contains the electricity company cartridge fuse of up to 100A. A PFC of up to 10kA sounds too high for a domestic situation though, as it would exceed the 6kA maximum breaking capacity of the main switch and breakers (MCB / RCD / RCBO) in a normal domestic consumer unit.
Current standards require the 25mm2 supply tails from the service head through the meter and to the consumer unit (everything after the meter is the customer's responsibility), with 16mm2 Protective ground conductor, connected to the PEN conductor at the service head.
The optional additional customer-side isolator is fitted on request (normally free if you remember to ask at the time of a meter change) and allows safe isolation procedure for an Electrician working on, or replacing the Consumer unit without the energy supplier call-out to remove and replace / re-seal the service head fuse. If you look at the cables coming down into the Consumer unit, you can see a 10mm2 earth bonding conductor (in this case daisy-chained) for the incoming Gas and Water service pipes.
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A more up to date and hopefully more representative / clearer TNC-S installation (situated in integral garage). Although the service head and incoming supply cable date back to the early 1980s.
Yes that's a better photo :)
The 3-phase street cable is paper insulated, so presumably the individual house branches are too. Each house is connected to one phase with PEN to the outer sheath. These connections are buried underground and inaccessible. If you look at the cable boot on the feed cable entry into the service head, you can see that the cable is coaxial with the PEN conductor forming the outer sheath. You can also see a Yellow disc on the back board, signifying that the house is on the Yellow phase of the street cable (old colour coding).
House branches installed the same time as the lead street main would have been lead but your cable looks like PVC concentric. I don't think I have ever seen a boot like that on a lead cable. Note also the "Protective Multiple Earthed" label bottom right indicating that it's TNC-S.
As richard.cs says, the service head contains the electricity company cartridge fuse of up to 100A. A PFC of up to 10kA sounds too high for a domestic situation though, as it would exceed the 6kA maximum breaking capacity of the main switch and breakers (MCB / RCD / RCBO) in a normal domestic consumer unit.
You are allowed PFC > consumer unit rating because the cartridge fuse is considered to be energy-limiting. You are correct that 10 kA would be uncommon, unless you are in central London or are right next to the transformer. Really rural areas can have a PFC of just a few hundred amps, these can have problems with fault clearance times and voltage drop on load (and should never be TNC-S).
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Yes, the cable does have a PVC outer covering - as does our street cable, which shorts and fails with monotonous regularity. The house builder apparently over-flexed it whilst laying it in clay soil. When water gets in, the cable paper insulation breaks down (one phase to PEN) and takes out the substation fuse. Strangely these don't tend to be hard faults, they normally have to replace the fuse several times, or fit an automatic re-closer, until the cable develops a permanent short. Our pavements are more patch than original, with tell-tale 'sniff test' holes drilled at regular intervals. I wish I had kept the cut out section from the spoil heap when it failed outside our house one Christmas Eve. It had a beautiful solidified Aluminium 'stalactite' running down the side. Unfortunately it kept oozing pitch, so tossed it back.
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Lots of photos covering a range of construction types and voltages here:
https://www.spenergynetworks.co.uk/userfiles/file/scottishpower_cables_equipment_metal_theft.pdf (https://www.spenergynetworks.co.uk/userfiles/file/scottishpower_cables_equipment_metal_theft.pdf)
is it me, or is this document a "guide for thieves ?"
Basically that UK houses typically have high-current single phase supplies. This is not really a very good idea, but the vast majority of domestic supplies, old and new, are single phase.
Yep. Same scheme here in France. It simplifies wiring you home, no need to balance your home, but you need a beefier incoming cable, and you are stuck with single phase.
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Basically that UK houses typically have high-current single phase supplies. This is not really a very good idea, but the vast majority of domestic supplies, old and new, are single phase.
Ohh, wow...
Now I understand why the UK plugs have built in fuses!
The detail which makes my hair stand on end is that the customers feed cable is only fused by the substation fuse.
This picture shows the road-side cabinet where my house is connected, they had to upgrade it to find space.
The main distribution cable in+out 4x150mm² go on the unfused blue clamps.
Usually the distribution is run in a sort of two-string zig-zag pattern along a residental road, this allows them to isolate one or two of these cabinets, while keeping power on the rest of the road. The unconnected cable on the right is one such fused "diagonal" connection, probably 4x100mm².
The white plugins hold three fuses or six fuses, and supply one or two cables.
The "drop" cables to the nearby installations are 4x6mm²
Because our house is 200m from this cabinet, they ran a 4x75mm² to another cabinet about halfway, that holds our 25A "mast-fuse" and the cable from there is 4x16mm².
One benefit of this system, is that the fire-brigade can pull the fuses when a house is on fire.
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Basically that UK houses typically have high-current single phase supplies. This is not really a very good idea, but the vast majority of domestic supplies, old and new, are single phase.
Ohh, wow...
Now I understand why the UK plugs have built in fuses!
That.. has absolutely nothing to do with it being a single phase supply.
The detail which makes my hair stand on end is that the customers feed cable is only fused by the substation fuse.
It's also protected by the fuse in the house. Mechanical damage is unlikely due to depth of burial.
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Basically that UK houses typically have high-current single phase supplies. This is not really a very good idea, but the vast majority of domestic supplies, old and new, are single phase.
Ohh, wow...
...
This picture shows the road-side cabinet where my house is connected, they had to upgrade it to find space.
The main distribution cable in+out 4x150mm² go on the unfused blue clamps.
Usually the distribution is run in a sort of two-string zig-zag pattern along a residental road, this allows them to isolate one or two of these cabinets, while keeping power on the rest of the road. The unconnected cable on the right is one such fused "diagonal" connection, probably 4x100mm².
The white plugins hold three fuses or six fuses, and supply one or two cables.
The "drop" cables to the nearby installations are 4x6mm²
Because our house is 200m from this cabinet, they ran a 4x75mm² to another cabinet about halfway, that holds our 25A "mast-fuse" and the cable from there is 4x16mm².
One benefit of this system, is that the fire-brigade can pull the fuses when a house is on fire.
That's a neat system - assuming the cabinets are physically secure against vandals, vehicle strikes, Copper thieves etc!
The fire-brigade access is very useful.
Now I understand why the UK plugs have built in fuses!
As Monkeh says, irrelevant, too far down stream of the house breakers (it's there to protect the appliance cable), but I suspect that it wasn't a serious comment.
The detail which makes my hair stand on end is that the customers feed cable is only fused by the substation fuse.
Yes, I agree with you on that one, it is a concern. The house feed cable, of smaller conductor area than the street cable isn't appropriately fused. The cable, whilst buried for most of its length, in older properties does come up through the house foundations and is exposed to some extent before entering the fused service head. In these properties, this entry is often under the stairs - a primary escape route.
Taking your 'plug fuse' comment as an example, there would, in all other circumstances, under the IEE wiring regs, be a protective device of appropriate rating to protect the house feed cable.
Electricity distribution companies are unfortunately a rule unto themselves. Whilst current edition wiring regs require things like non-combustible consumer units to reduce fire risk, they are not required to follow them (they have their own codes of practice) and continue to install plastic cased service heads, isolators and meters new-builds (and upgrades - as my previous photo). They are, however, now brought up into a plastic cabinet built into the outer wall of the building. This houses the service head, meter and hopefully an isolator switch, with the connection to the customer's consumer unit inside the property via 25mm2 double insulated tails. This should mean that any supply related fire should occur only on the outside of the building.
I don't believe that the supplier equipment is a significant cause of domestic fires (as badly installed (loose connections) older plastic consumer units can be. I think this is probably due to careful installation, but the small risk is there.
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I don't believe that the supplier equipment is a significant cause of domestic fires (as badly installed (loose connections) older plastic consumer units can be. I think this is probably due to careful installation, but the small risk is there.
Meter installers yanking on the tails is a significant cause of fires in otherwise perfectly good CUs, for which they take no responsibility whatsoever..
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Meter installers yanking on the tails is a significant cause of fires in otherwise perfectly good CUs, for which they take no responsibility whatsoever..
Yes, I've heard of that one too!
Thick stranded cables with few strands suffer from 'strand shuffle' when flexed, which can loosen clamping screws. A standard 25mm2 tail has 7 strands, while 'flexi-tails' have 25 strands.
EDIT: I know from recent experience that they don't open the consumer unit to check the clamping screws afterwards - a case of not their property, not their problem!
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Now I understand why the UK plugs have built in fuses!
That.. has absolutely nothing to do with it being a single phase supply.
It was a comment on the "architecture" of the overall solution :-)
As for the road-side cabinets here in Denmark:
They seem remarkably resilient, everything in them is well insulated by plastic, and even when hit by a car, they mostly seem to keep working as intended.
They seem to have a "frangible zone", they seem bend over around ground level with the actual box being pretty intact.
After a hit they get inspected, and if anything could possibly be exposed, they are wrapped in a solid orange plastic bag with warning signs.
Proper fixing happens some weeks or months later.
There isn't much of an opportunity for stealing copper in these cabinets, the cables go straight into the ground and the fat ones are usually alu.
(Denmark have no native metal ores, all metal is imported, this gave norwegian alu an early leg up in our cabling.)
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Large single-phase house supply is also common in the USA.
Three-phase power only has point in distribution, and running large motors off the line directly.
In homes, 3-phase power itself has had very little use and sees less and less use due to availability of variable frequency drives. From the household perspective, 3-phase power is like three separate power lines, fused separately. The problem is the small fuse size. Here, 3x25A is the most typical household fuse size. Assuming I never want to drive classical off-the-line 3-phase motor loads, I would take 1x75A over it any day. Same nominal power, but a lot more actually usable power.
25A is such small current that 3x25A requires careful balancing acts for many households and even then it's quite common to accidentally blow the main 25A fuses.
Of course, from power company viewpoint, this is superb because the difficult task of balancing is forced down the throats of the households. Because 25A is so little, everyone has to do some balancing and large resistive loads have to be designed to load all phases equally. So now a home with a 10kW heater is in perfect balance, unlike a system where single-phase supply is used and one house has a 10kW heater and the neighbor does not.
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25A is such small current that 3x25A requires careful balancing acts for many households and even then it's quite common to accidentally blow the main 25A fuses.
I think it is important for the discussion that we all understand how much this is "per-country" due to political and technological history.
Even between the nordic countries there are huge differences, for instance in EV uptake or how much resitive heating is used, it has been almost outlawed in DK since 1973, whereas I belive it is still pretty much the norm in NO and FI (not sure about SE).
I was surprised to discover that my swedish ground-circuit heat-pump came with three current transformers to be installed at the infeed, so that the compressor could avoid overloading the 3x25A. Here in DK it seems to be regular practice to just put them on the heat-pumps own cable, but I insisted them mount them in the infeed, but so far they have never had any effect.
But their very existence support your argument, that this is a concern other places.
Having worked in computing reliability for decades, I'll take three separate fuses over one fuse any time, and speaking from experience, designing the installation in a new house to distribute the load over three phases is really not an issue According to my monitoring, we peak out at 20A.
But yes, adding an electrical car would require 3x35A, but that is just a one-time fee here in DK, so I dont consider it a problem?
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But yes, adding an electrical car would require 3x35A, but that is just a one-time fee here in DK, so I dont consider it a problem?
Just so I understand, you are saying that a typical home only has 25 amp service on a three phase circuit? Also, for some reason, EV charging it typically done with a 35 amp, three phase circuit?
I don't know if your country requires derating the current on a circuit like we do here in the US for continuous loads. If not, that gives 15 kW at 240V. That's a lot of charging rate and seems not necessary. It will charge my car from 0 to 100% in under 7 hours. A real world need would be much less. It could easily charge overnight on a 20 amp circuit, which is 8 kW.
I know in the UK they use 9 amp tea kettles. It would seem a 25 amp circuit for a whole house means limited usage of electricity for heating, either the home or water. My hot water heater is on a 30 amp, 240 volt circuit actually drawing 18 amps and over 4 kW. Instant on hot water heating must draw more current since my heater won't keep up with taking a shower.
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But yes, adding an electrical car would require 3x35A, but that is just a one-time fee here in DK, so I dont consider it a problem?
Just so I understand, you are saying that a typical home only has 25 amp service on a three phase circuit? Also, for some reason, EV charging it typically done with a 35 amp, three phase circuit?
Yes, the default "mast fuse" here in Denmark is 3x25A.
If I add EV charging on top of our current load pattern, it would require the "mast fuses" to be upgraded from 3x25A to 3x35A.
That is literally all there is to it: Change the fuses, pay the "investment fee" (as you now have bigger access to the grid) and you're done.
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I know in the UK they use 9 amp tea kettles. It would seem a 25 amp circuit for a whole house means limited usage of electricity for heating, either the home or water. My hot water heater is on a 30 amp, 240 volt circuit actually drawing 18 amps and over 4 kW. Instant on hot water heating must draw more current since my heater won't keep up with taking a shower.
Two things: The fuses we are talking about, are slow fuses. It will take 25A sustained forever, and brewing a cup of tea, even if it puts you at 34A for a few minutes, will not blow the fuse.
Your 240V/18A hot water heater would claim 18/(3*25) = 24% of the available continuous capacity, but it runs only every so often and the chances that it, the oven, the dishwasher, the washer, the dryer and the hair-dryer all being on a the same time is practically non-existent, and even then, it would only be for a few minutes.
The trouble is when you add a huge "base-load" like EV-charging: That constant hour-long load steals the head-room, and means that the probability of intermittent loads may push the fuse to blow increases a lot.
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I know in the UK they use 9 amp tea kettles. It would seem a 25 amp circuit for a whole house means limited usage of electricity for heating, either the home or water. My hot water heater is on a 30 amp, 240 volt circuit actually drawing 18 amps and over 4 kW. Instant on hot water heating must draw more current since my heater won't keep up with taking a shower.
Err... UK kettles can be up to 3KW, which is 12.5A @240V.
If they use an IEC 60320 C15/C16 hot condition connector pair, then they should be under 10A due to the connector's limitations, but its increasingly rare to find such kettles. Really old kettles used a round 13A connector - see: https://www.amazon.co.uk/Spares2go-Universal-Element-Connector-Grommet/dp/B00TFTKXNQ (https://www.amazon.co.uk/Spares2go-Universal-Element-Connector-Grommet/dp/B00TFTKXNQ)
Many older homes in the UK were on 60A single phase feeds, and didn't have enough current available for permanently installed high wattage electric heating/cooking appliances. I would expect that such installations are now vanishingly rare, as in most cases they would have been upgraded to 100A feeds when the fuse board was replaced with a modern consumer unit.
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I know in the UK they use 9 amp tea kettles. It would seem a 25 amp circuit for a whole house means limited usage of electricity for heating, either the home or water. My hot water heater is on a 30 amp, 240 volt circuit actually drawing 18 amps and over 4 kW. Instant on hot water heating must draw more current since my heater won't keep up with taking a shower.
Two things: The fuses we are talking about, are slow fuses. It will take 25A sustained forever, and brewing a cup of tea, even if it puts you at 34A for a few minutes, will not blow the fuse.
Your 240V/18A hot water heater would claim 18/(3*25) = 24% of the available continuous capacity, but it runs only every so often and the chances that it, the oven, the dishwasher, the washer, the dryer and the hair-dryer all being on a the same time is practically non-existent, and even then, it would only be for a few minutes.
The trouble is when you add a huge "base-load" like EV-charging: That constant hour-long load steals the head-room, and means that the probability of intermittent loads may push the fuse to blow increases a lot.
A number of EV chargers have options for incomer current transformers, this way they can back-down the charge current to limit the peak load. I haven't seen this done often in domestic UK installs.
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A number of EV chargers have options for incomer current transformers, this way they can back-down the charge current to limit the peak load. I haven't seen this done often in domestic UK installs.
Yeah, same as my heat-pump.
But do you want to bet that if both the EV charger and the heat-pump monitor the infeed current, they're going to confuse each other mightily ?
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I think it is important for the discussion that we all understand how much this is "per-country" due to political and technological history.
Even between the nordic countries there are huge differences, for instance in EV uptake or how much resitive heating is used, it has been almost outlawed in DK since 1973, whereas I belive it is still pretty much the norm in NO and FI (not sure about SE).
...
But yes, adding an electrical car would require 3x35A, but that is just a one-time fee here in DK, so I dont consider it a problem?
Here, 3x35A is significantly higher monthly fee than 3x25A so most try to live with 3x25A (which usually is doable) unless they really need 3x35A. For example, here, 19.67 €/month vs. 33.96 €/month. It seems like waste if you only need it rarely, or can handle the situation by some careful balancing act instead.
And of course the 25A fuse can take 35A for quite some time (a few minutes 100% guaranteed; likely tens of minutes; possibly hours).
In any case, our eco-government is now paying a 2500€ subsidy if we dismantle working oil heating system and replace with direct electric heating; or 4000€ if replaced by air-to-water heat pump, which is what I did (haven't got my 4000€ yet, though). In any case, every air-to-water heat pump* revert to being simple direct electric heaters when the temperature drops to below around -20 to -25degC which is commonplace enough. This obviously coincides with when heating power is required the most; so now your 2.5kW input, 9kW output investment is temporarily just an expensive decoration which inputs 9kW to output 9kW. The grid here mostly can take it no problem, but production is a big question mark, because for a some years now, Finland has been buying electrical energy from all neighbors. Gone are the days of buying from Russia and selling to Sweden. This winter, Sweden had close calls with their own supply and demand but thankfully were still able to sell us.
*) except a very few very expensive models, but even those won't have COP much over say 1.5 at such extreme temperature differential
The change is big, most homes built before 1990's use oil heating. Keeping existing, working oil-based burners as support devices for the few coldest days, still only contributing a few % to the total CO2 emission, would totally make sense. Most of the population live in areas where there are typically less than 5-10 days per winter of such low temperatures that air-source heat pumps have to rest (or work at ridiculously low COP say <1.5), but you need to design the whole infrastructure to be able to get through those days, and now suddenly we will have tens of thousands more households running with direct electric heating (so some 10kW). Which is 3x16A so you have 9A left per phase for everything else.
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This is a great thread.
ie, what is causing the overvoltages experienced by OP?
I wish we could summarise all the salient points of this post, distill them into a few lines.
From my reading, it looks to me that there is almost definetely some kind of problem with the neutral connection. Its got damage such that it goes disconnected or high Z every now and then....intermittently. Although possibly it may be compromised all the time, and just waits till the 3 phase loads get unbalanced before giving the overvoltage.
There is possibly corrosion into the cable somewhere along the underground connection, and it would be very expensive for the power company to find out exactly where this point is.
I am just thinking....maybe what is needed is to chop the mains input to the house, at the house gates......and build a switch mode battery charger, with ability to handle up to 415VAC.....then put a big battery there, and make it (the mains input bit that got chopped) charge the battery....then put an AC generator at the battery, and make that give 240VAC to the house.
I suspect this is going to be the cheapest way round this problem....and make the power company pay for it.
Failing this, put up little pylons from the nearest substation to the house...and get the power company to pay for it....a fresh mains connection.
I wouldnt mind betting that the power company would rather pay OP for his house, then bulldoze it!
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A number of EV chargers have options for incomer current transformers, this way they can back-down the charge current to limit the peak load. I haven't seen this done often in domestic UK installs.
Yeah, same as my heat-pump.
But do you want to bet that if both the EV charger and the heat-pump monitor the infeed current, they're going to confuse each other mightily ?
The EV charger I have here in France is connected to the communication bus of the main "meter" (well, smart meter: counter + fuse + real time stats uplink to the distributor).
It is a standard feature of my french-made charger. The charger lowers the charge current when it detects it is close to the limit. No config needed. From the bus it can read the max allowed, the present overall load, and it knows its own load. (Not that I ever needed it, as I am on 45A single phase and don't have electric heating nor a large heat pump.) That communication bus (TIC: télé-information client) has been around for a while now, it was even present on the previous non-"smart" generation, it was just upgraded a bit for the new meter.
And yes, if you have two devices that do this, they may start a fight.
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I think it is important for the discussion that we all understand how much this is "per-country" due to political and technological history.
Even between the nordic countries there are huge differences, for instance in EV uptake or how much resitive heating is used, it has been almost outlawed in DK since 1973, whereas I belive it is still pretty much the norm in NO and FI (not sure about SE).
...
But yes, adding an electrical car would require 3x35A, but that is just a one-time fee here in DK, so I dont consider it a problem?
I don't agree that 35A circuits are required to charge an EV. I charge my model X from 120V, 1.4 kW. My situation is unusual, but nearly no one needs the full power of a 35A, 3 phase circuit (15 kW) for home EV charging. EVs get around 4-5 mi/kWh (I'll let you convert that to km if needed). So a 5 kW charge rate (half of the 25A supply) gives 20 miles/hr. How much do you drive in a day? A 12 hour overnight charge would supply 240 miles (pretty much a full charge on most EVs).
In any case, our eco-government is now paying a 2500€ subsidy if we dismantle working oil heating system and replace with direct electric heating; or 4000€ if replaced by air-to-water heat pump, which is what I did (haven't got my 4000€ yet, though). In any case, every air-to-water heat pump* revert to being simple direct electric heaters when the temperature drops to below around -20 to -25degC which is commonplace enough. This obviously coincides with when heating power is required the most; so now your 2.5kW input, 9kW output investment is temporarily just an expensive decoration which inputs 9kW to output 9kW.
Here systems are mostly air to air and convert to resistance heating much below freezing, say -8 °C. That is in no small part because the systems are hit on both ends. A heat pump pushes heat uphill. Air to air requires more heat to be moved AND makes the hill larger. Air to water has a constant water temperature but requires more heat to be moved, so is less impacted by the outside temperature. By "air to water" I'm assuming you mean ground water, no? Buried coils in the ground or even a well pumping water for cooling?
The grid here mostly can take it no problem, but production is a big question mark, because for a some years now, Finland has been buying electrical energy from all neighbors. Gone are the days of buying from Russia and selling to Sweden. This winter, Sweden had close calls with their own supply and demand but thankfully were still able to sell us.
*) except a very few very expensive models, but even those won't have COP much over say 1.5 at such extreme temperature differential
The change is big, most homes built before 1990's use oil heating. Keeping existing, working oil-based burners as support devices for the few coldest days, still only contributing a few % to the total CO2 emission, would totally make sense. Most of the population live in areas where there are typically less than 5-10 days per winter of such low temperatures that air-source heat pumps have to rest (or work at ridiculously low COP say <1.5), but you need to design the whole infrastructure to be able to get through those days, and now suddenly we will have tens of thousands more households running with direct electric heating (so some 10kW). Which is 3x16A so you have 9A left per phase for everything else.
The coldest days are typically clear (heat radiating into space). Residential solar can assist in those times. Of course some sort of storage is required for night. That's a bigger challenge. Direct water heating is actually very effective and inexpensive. That can be supplemented for night heating, but requires water circulation which is not so common these days.
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I don't agree that 35A circuits are required to charge an EV. I charge my model X from 120V, 1.4 kW. My situation is unusual, but nearly no one needs the full power of a 35A, 3 phase circuit (15 kW) for home EV charging.
Yes exactly.
I have a 45A limit on my single phase 230V supply, and did not even consider upgrading that since 2 years of having an EV.
Charging 16A every night (3,7kW), occasionally upping it to 32A when faster charging is really needed.
In some rare cases, you can avoid the upgrade using a smart regulating EVSE or similar.
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I wasn't expecting to disconnect PE (though note it is now common for EV chargers to disconnect PE in the event of lost TNC-S neutral, yey for ugly workarounds).
What the.. I design EV chargers and not aware of anything like that. PE bonding is one of the tests safety agencies do when certifying the product. Can you elaborate?
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I wasn't expecting to disconnect PE (though note it is now common for EV chargers to disconnect PE in the event of lost TNC-S neutral, yey for ugly workarounds).
What the.. I design EV chargers and not aware of anything like that. PE bonding is one of the tests safety agencies do when certifying the product. Can you elaborate?
UK chargers should by law protect against broken PEN. One of the rare fault modes that can effectively leave the PE (and car body) floating, or worse still at live voltages. Some manufacturers do this by disconnecting the L1, L2, L3, N and PE on the cable. If you look-up the Zappi 2, you'll see an earth disconnection relay.
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Here systems are mostly air to air and convert to resistance heating much below freezing, say -8 °C. That is in no small part because the systems are hit on both ends. A heat pump pushes heat uphill. Air to air requires more heat to be moved AND makes the hill larger. Air to water has a constant water temperature but requires more heat to be moved, so is less impacted by the outside temperature. By "air to water" I'm assuming you mean ground water, no? Buried coils in the ground or even a well pumping water for cooling?
No, I mean air to water as in air is the source. Basically, take a bog standard air-to-air heat pump outdoor unit, but replace the indoor unit with plate heat exchanger releasing the heat to water. Why? Because now you can connect it to the existing central heating system. You can also store the heat in water easily, which is something not very trendy right now but nevertheless I'm doing that.
In air-to-water, low temperatures really hurt because unlike air-to-air where the condenser (indoor unit) has large surface area + fan and thus can keep producing fairly constant 25-26 degC air, air-to-water is usually connected to the existing radiator system which, even if generously sized, requires temperatures in excess of 45 degC so that the radiators give enough power output with natural convection. Best case, in-floor heating can work with lower water temperatures.
Pumping from -25 outdoor air to +50 central heating loop is quite a task to do; very best models can pull that off with COP near 2! But it's not worth investing 10000€ to do that if a 3000€ unit does almost the same except for the few coldest days.
Ground source is obviously ultimate in very cold climates and easy to design because the source temperature is constantly around +5 degC even in cold climates, given generous energy well sizing. Too small and it freezes though. Fairly expensive to install. Requires bureaucracy here. Typical install cost near 20k€.
The coldest days are typically clear (heat radiating into space). Residential solar can assist in those times.
I have a 3kW PV system but the generation in coldest months - Jan and Feb - was exactly zero this year. You could clear the snow off the panels, yes, but the output would be still utterly minuscule, maybe in a good cold sunny day in January you'd get 3-4kWh and need 100kWh for heating that day. Now in Apr or May I get, depending of cloudiness, 20% to 60% of my heat consumption from PV, and this is with direct electric heating. With heat pump COP=3.0, this translates to 60% to 180%!
But the problem here is that Finland is an extremely dark country in winter, we have this thing called Gulf stream enabling us to somehow live here, but climatically equivalent areas in North America for example are much more down south, hence you have a lot more light there.
So it makes perfect sense to burn fossils during the two months of cold darkness and you can compensate during the remaining year.
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Here systems are mostly air to air and convert to resistance heating much below freezing, say -8 °C. That is in no small part because the systems are hit on both ends. A heat pump pushes heat uphill. Air to air requires more heat to be moved AND makes the hill larger. Air to water has a constant water temperature but requires more heat to be moved, so is less impacted by the outside temperature. By "air to water" I'm assuming you mean ground water, no? Buried coils in the ground or even a well pumping water for cooling?
No, I mean air to water as in air is the source. Basically, take a bog standard air-to-air heat pump outdoor unit, but replace the indoor unit with plate heat exchanger releasing the heat to water. Why? Because now you can connect it to the existing central heating system. You can also store the heat in water easily, which is something not very trendy right now but nevertheless I'm doing that.
In air-to-water, low temperatures really hurt because unlike air-to-air where the condenser (indoor unit) has large surface area + fan and thus can keep producing fairly constant 25-26 degC air, air-to-water is usually connected to the existing radiator system which, even if generously sized, requires temperatures in excess of 45 degC so that the radiators give enough power output with natural convection. Best case, in-floor heating can work with lower water temperatures.
Part of the problem is a heating system that tries to generate 45 °C or worse 50 °C. My heating system is forced air and only needs to generate about 35 °C, big difference.
Pumping from -25 outdoor air to +50 central heating loop is quite a task to do; very best models can pull that off with COP near 2! But it's not worth investing 10000€ to do that if a 3000€ unit does almost the same except for the few coldest days.
My point is the COP falls, but it is never below 1.0, so it can keep running and the direct resistance heat can just be supplemental.
Ground source is obviously ultimate in very cold climates and easy to design because the source temperature is constantly around +5 degC even in cold climates, given generous energy well sizing. Too small and it freezes though. Fairly expensive to install. Requires bureaucracy here. Typical install cost near 20k€.
I considered installing it at one point, but they would not give a total price. Seems they want no risk from the cost of digging to install the ground loop. I sent the guy packing. I don't know how they can sell residentially without giving a firm price quote.
The coldest days are typically clear (heat radiating into space). Residential solar can assist in those times.
I have a 3kW PV system but the generation in coldest months - Jan and Feb - was exactly zero this year. You could clear the snow off the panels, yes, but the output would be still utterly minuscule, maybe in a good cold sunny day in January you'd get 3-4kWh and need 100kWh for heating that day. Now in Apr or May I get, depending of cloudiness, 20% to 60% of my heat consumption from PV, and this is with direct electric heating. With heat pump COP=3.0, this translates to 60% to 180%!
3 kW is not a very large PV system at all. Not sure how your monthly generation could be zero however. Can you explain that a bit? Are you saying you live somewhere that the snow on the panels never melts for 60 straight days?
But the problem here is that Finland is an extremely dark country in winter, we have this thing called Gulf stream enabling us to somehow live here, but climatically equivalent areas in North America for example are much more down south, hence you have a lot more light there.
So it makes perfect sense to burn fossils during the two months of cold darkness and you can compensate during the remaining year.
Not exactly. We are very accustomed to burning fossil fuels and not giving it much thought other than that we should stop at "some point" or that we need to ''cut back" like being on a diet. The reality is we need to STOP burning fossil fuels, end of story. We can't do that over night, but some other energy source is required. The fact that solar is not ideal and that we need to continue development on various non-fossil energy sources does not mean we should just accept that using fossil fuels is inevitable. We can do better and we will... unless we treat global warming like the COVID pandemic in Florida and just accept things without taking the actions we should.
I do have to applaud you for having a PV system which I don't. I've not been willing to cut down my trees. Maybe I can get my neighbor, who has clear cut his property, to let me put PV on his pole barn roof!
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If your local Neutral and imported earth is being significantly disturbed from the local earth (defined as an earth rod) because of phase imbalance on a long feed then you could see other issues with metalwork being at several volts above ground and possibly significant current flowing via your water and gas pipes into the ground. This is not a good situation as it might indicate a potential neutral fault which is extremely dangerous.
One solution to this would be to get your installation converted to TT from TNCS/TNS but this has to be done carefully if you have near neighbours who are on TNCS/TNS. It won't fix your high voltage but at least everything will stay properly grounded!
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3 kW is not a very large PV system at all. Not sure how your monthly generation could be zero however. Can you explain that a bit? Are you saying you live somewhere that the snow on the panels never melts for 60 straight days?
Thick layer of snow for nearly three months straight. Normal here. Not every year for that long, but maybe every 3-4 years. Yes, you could remove the snow but it's not worth the hassle for maybe some 30 kWh/month generation. Later in spring, you get the same in two days.
Yes it's small, I dont't know why the previous owner cheaped out, there's room on the roof for many more panels and I'm sure the additional cost once the installers were on the premises would have been negligible. Anyway, I'm going to expand it. A 5-6kWh system, maybe up to near 10kWh now that panels are cheap, would be the sweet spot between investment cost and production. Too large and you produce excess power and need to sell it for cheap.
Here we have just to accept basically no solar generation for three months, but especially in springtime production is great and already a rather small 3kW system combined with air source heat pumping gives you almost full self sustainable energy!
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3 kW is not a very large PV system at all. Not sure how your monthly generation could be zero however. Can you explain that a bit? Are you saying you live somewhere that the snow on the panels never melts for 60 straight days?
Thick layer of snow for nearly three months straight. Normal here. Not every year for that long, but maybe every 3-4 years. Yes, you could remove the snow but it's not worth the hassle for maybe some 30 kWh/month generation. Later in spring, you get the same in two days.
Yes it's small, I dont't know why the previous owner cheaped out, there's room on the roof for many more panels and I'm sure the additional cost once the installers were on the premises would have been negligible. Anyway, I'm going to expand it. A 5-6kWh system, maybe up to near 10kWh now that panels are cheap, would be the sweet spot between investment cost and production. Too large and you produce excess power and need to sell it for cheap.
Here we have just to accept basically no solar generation for three months, but especially in springtime production is great and already a rather small 3kW system combined with air source heat pumping gives you almost full self sustainable energy!
Seems like both solar and heat pumps are rather marginal where you are. How many hours of sunlight do you get on Dec 20?
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Would you do better with vertical panels on a South facing wall, would that be enough to be self-clearing? Taking a stab at you being about 65 degrees North, this calculator puts your optimum January angle as just 9 degrees from vertical. http://www.solarelectricityhandbook.com/solar-angle-calculator.html (http://www.solarelectricityhandbook.com/solar-angle-calculator.html)
Using their irradiance calculator you can then work out what your expected output would be for a given array size at that angle.
http://www.solarelectricityhandbook.com/solar-irradiance.html (http://www.solarelectricityhandbook.com/solar-irradiance.html)
I think that website also uses historic weather data rather than being entirely geometry based, so should account for average cloud. It looks like you loose about 30% off the summer performance compared with roof-angled panels, but if it keeps the snow off when you need most power in winter maybe it's worth it.
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Would you do better with vertical panels on a South facing wall,
If your goal is "maximize minimum daily energy" and you are in the nordic countries, vertical south facing panels is the optimum config.
I can highly recommend EU's PV estimator webapp: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html
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I can highly recommend EU's PV estimator webapp: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html
Thanks, I wasn't aware of that one.
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Seems like both solar and heat pumps are rather marginal where you are. How many hours of sunlight do you get on Dec 20?
5 hours from sunrise to sunset but obviously at such low angle that even small trees and buildings, anything not a completely flat horizon, make it 2-3 hours and that is quite low angle as well.
Last December was 3 kWh of production for the whole month. The same I produce in one hour in a sunny day at good angle. But this is because last December only had TWO even remotely sunny days. Rest was all cloudy and foggy all the time; very typical December. The combination of cloud, fog and low solar angle is the killer. Now if I have a similarly cloudy and foggy day in May, I get maybe 3-4 kWh per such day. In December it's 0. It's also depressing!
But the total yearly insolation in Finland is not bad at all, it's only marginally worse than middle Europe or northern USA for example. It's just that we get little to no production for two months, quite limited production for another two, the rest is just fine or even very good.
So yes, part of the time it's marginal, basically ROI lengthens by some 30% compared to middle Europe for example. But nowadays, ROI for solar installations is so good this isn't a problem IMHO. I'm definitely going to install more solar despite it being useless part of the year. Probably south facing at steep angle to boost winter time production as suggested by richard.cs.
Air source heat pumping isn't marginal in Southern Finland if you buy machines capable of low-temperature operation; temperatures below -20degC (down to -30degC) are reality but the number of such days per year is usually just 5-10, so just use alternative sources for those days, direct electric heating being simplest, burn wood or even untrendy oil, no big deal in total cost nor total CO2 because it's a few % of yearly energy. Air-source heat pumping works very well to about -10 to -15degC, and most of the heating energy is spent approximately in such conditions.
BTW, one of the biggest challenges in designing a cold environment air source heat pump is the defrost algorithm, in particular how the unit decides when the evaporator is blocked due to freezing and needs defrosting. Freezing itself lowers both COP and power output, but because defrosting wastes energy, false positives also totally kill the COP. If you ignore the freezing issue, designing an unit to operate with large dT is fairly trivial, just some component and refrigerant optimization engineers do all the time. But buggy defrost algorithm can totally kill an otherwise well designed pump as evidenced by recent problems in some top-of-the-line Mitsubishi Electric air-to-air heatpump models that enter endless defrost-after-defrost loop and just stop working.
Would you do better with vertical panels on a South facing wall, would that be enough to be self-clearing?
Not only self-clearing, but also in a pretty good angle for those winter days. Such installations can be seen here, it's generally a good idea if self-sustainability (i.e., energy production for oneself when it is needed) is the target. Yearly total production suffers significantly, but OTOH, does it make sense to produce excess energy in summer when everyone else is also producing in excess, and sell it for peanuts?
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Would you do better with vertical panels on a South facing wall, would that be enough to be self-clearing?
Not only self-clearing, but also in a pretty good angle for those winter days. Such installations can be seen here, it's generally a good idea if self-sustainability (i.e., energy production for oneself when it is needed) is the target. Yearly total production suffers significantly, but OTOH, does it make sense to produce excess energy in summer when everyone else is also producing in excess, and sell it for peanuts?
Sounds like a problem of locality of supply/demand. Doesn't your country share with others to the south? I don't pretend to know the geography and climate of the region, but here most places have summer peaks of demand in the late after noon. My Time of Use billing is 3 to 7 pm where my cost of electricity is 10x the off peak rates. I would think that would make for excellent returns if your country had energy sharing agreements with other, more southern countries.
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Sounds like a problem of locality of supply/demand. Doesn't your country share with others to the south?
Well, right now the issue is what I think applies to basically everywhere: if you sell to the grid, you are paid less than when you buy from grid. For me, it's 0.13€/kWh to buy and 0.05€/kWh to sell. (Yes, we have cheap electricity compared to Germany for example!) There are special arrangements where you are paid the same but then need to pay some fixed monthly fee to enable that arrangement.
I was a bit futuristic with my remark. With the current trend in solar installations, my expectation is that maybe in 10 years, hourly rates are forced down our throats and during peak generation the difference between selling in summer vs. buying in winter develops even larger gap than what it currently is, the conclusion anyway being that even with the current gap in sell vs. buy prices, maybe it's a good idea to choose the slope angle for winter production (or morning/evening production) at the expense of generating less than maximum theoretical energy, but being able to use more by yourself.
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With the practicality of residential power generation, it would seem the monopolistic model of electricity sales is going to need changes. The local utility will be needed for distribution, but the billing for the kWh consumption and generation can and should be turned into an open market.
Again, I don't know your country's methods and in the US it varies by state and even the individual utility. One of my homes has competitive energy supplier(s), however it was never a widely sourced market. Prior to that the entire package was handled by the local utility. Politicians opened up the market saying it would provide for lower prices on a competitive market. Instead some utilities within the state spun off their power generation and someone made big money on unregulated pricing with residential bills doubling in some areas. Another home is on a coop which means the users are also stockholders and any profits are applied to the bills. The prices at the two homes are pretty much the same.
Here utilities have some political clout, as does any large company, being able to pay for PR and lobbyists. Still, as the nature of electrical generation becomes more complex, I expect the utilities to morph into less electricity suppliers and more electricity buffers and market makers. With solar and wind generation, storage is required which may be less expensive at the utility level. Certainly wind power is lower cost when installed with large turbines rather than home size, so that will remain a utility level source. But solar can be mounted on homes keeping much of the generation close to the source reducing the need for external generation as well as transmission, mostly needing storage and local distribution.
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my expectation is that maybe in 10 years, hourly rates are forced down our throats
People usually do not realize how much history, technological and political, there is under that statement.
One of the things we found when we cleaned up after my grandparents, was an old "milking-schedule": Each farmer was assigned a time-slot for running his milking machine, because the local power-plant was not big enough to run them all at the same time. That was not even 100 years ago.
Then a huge consolidation took place, where AC backbone grids took that concern away and like running water, electricity became a "utility": You just open when you need some.
If the economics of production are benign and predictable, charging for the annual consumption at the average rate, makes a lot of sense: It gives you the lowest possible overhead costs.
But if the economics of production are unpredictable, if you have droughts or shortfall of electricity production, you cannot do that, and before you go back to issuing "milking-schedules", trying to make people think about when they consume is a good first step.
When you plan a trip into town, you consider the expected traffic[1] and you probably try to avoid the most crowded times at the shopping centre.
There is no reason why it should be any different for electricity, or for that matter, water, when drought parches California or Australia.
The crucial thing however, is that the markets must be tightly regulated, so that prices dont peak simply because som antisocial asshole can make money that way (See also: ENRON), it must be a legitimate price-signal to indicate that we would all fare better, if some people tried to shift their consumption.
Unfortunately, deregulated markets heavily favour the assholes.
[1] Full disclosure: The few times I've been in Finland I've never seen congestion, not sure if this example applies there.
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But if the economics of production are unpredictable, if you have droughts or shortfall of electricity production, you cannot do that, and before you go back to issuing "milking-schedules", trying to make people think about when they consume is a good first step.
Yep. And it is a positive thing!
Forget flat-priced electricity. Producing electricity is not flat-cost! Why on earth should the supplier take the risk ?
In some countries, this already exists, and you have a few options :
- flat rate, pay more on average (like today)
- variable rate, pay a bit less on average
- variable rate, pay much less by managing your loads a bit (intelligent ones will come more and more)
- produce yourself, with PV, batteries, V2G etc...
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Yep. And it is a positive thing!
Yes, as I said: If the market works, and governments regulate them properly, so vulnerable consumers do not get exploited at every possible turn.
We dont need another ENRON.
And Texas saw this winter what happens when the governmental regulation does not work.
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Is this still the thread about too high voltage in a home? Seems the kilt is tilted.
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Is this still the thread about too high voltage in a home? Seems the kilt is tilted.
Yes it is, eyesight 20/20. Feel free to post about too high voltage in a home. If you have anything to say, that is.