Electronics > Power & Renewable Energy

Constant High Mains Voltages At Home

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paul_g_787:
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.

mikeselectricstuff:
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

Ice-Tea:
Try something like this:

https://www.ombudsman-services.org/sectors/energy

?

themadhippy:

--- Quote ---Can anyone make a suggestion what I should do?
--- End quote ---
send british gas invoices for all the electrical equipment  damaged by the over voltage starting with the ups

IanB:

--- Quote from: paul_g_787 on April 16, 2021, 05:51:30 pm ---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.
--- End quote ---

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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