House mains electricity issues

[james_s]

I always use spec grade receptacles myself, usually Pass & Seymore because that's what the local shop stocks. For switches the cheap ones seem to work ok but with receptacles it definitely makes a difference.

Doesn't take long to use the screw terminals but does take longer than just poking the wires in the holes and it adds up if you're building houses and installing hundreds of them.

[P90]

In my own house I had yet another backstab terminal on a cheap receptacle fail, I was fortunate in that the load was small and the end of the wire oxidized heavily enough that it opened the circuit rather than causing a big meltdown. [...] The spring loaded backstab terminals are horrible, I wish they would ban them.

I absolutely loathe those "builder grade" stab-only plugs. When I see them they're usually falling apart with chunks of plastic missing, and are barely able to hold the prongs of a plug anymore.

I went through a few years ago and ripped out all the ones in my house and replaced them with Leviton "Industrial Grade" receptacles. Also the similarly cheesy light switches were chucked and replace with the similarly rugged Leviton "Industrial Grade" 277 volt versions. Ugly plastic cover plates were all replaced with brushed stainless steel. Not that expensive all things considered, and I will probably never need to replace them again.

Industrial or Hospital grade is the way to go for receptacles. A night and day difference; now it actually takes force to remove plugs, they don't just fall out under their own weight.

Also, it hardly takes more than a few seconds to properly terminate wires with screw terminals. How lazy can you get? I suppose stabs really aren't out of character though, given the overall shoddy, minimum effort level of work you see in residential electric.

Unfortunately, from what I've seen, that shoddy, minimum effort level work isn't only associated with electrical, rather all aspects of new construction...

[P90]

I always buy the spec grade outlets, the cheap $1.19 ones fall apart before you get to the job to install them, they are plastic welded halves, the spec grade have more metal and better contacts, plus the screw connections are poke and screw like gfci outlets.

[Monkeh]

By 'Wago' I'm assuming you mean a specific spring clip connector, rather than the higher end stuff they make.

I mean their installation connectors in general. I've used most types - full size and compact push-in (773 and 2273 series), lever action (222 and 221 series), and the lighting connectors (I want to say 224 series, I have none on hand). Also various older types and clones thereof (tend to avoid those).

I find them appealing, compact, convenient, error-resistant, and easy to inspect.  But I can see they are not necessarily a better connector.  The contact points are small and concentrated.  One side bites into the wire at almost a single point.  The other side might make a longer contact, but it's not certain to and the contact area is small.

The contact points are more than adequate for the size of conductor they are rated for. Only one side is a current-carrying contact, the other is merely the spring load.

In contrast a wire nut is used with twisted-together wires that deform to have a large contact area.  The helical steel spring inside forms threads into the wire at multiple points for high retention strength and the multiple wraps of the spring results in a high contact force.  If the connection is made correctly, it is stronger and lower resistance.  (The 'if' part is a big weakness.)

And also unwanted deformation of the wires, work hardening, and stretching. There's no need for a lower contact resistance as it's already less than the resistance of the stripped wire you insert.

as you seems to be the top notch engineer around here based on your "intelligent and informative" posts, maybe you can start elaborating why is that so. https://www.alibaba.com/product-detail/Kenya-Hot-selling-PVC-insulation-Copper_60472362866.html

Err.. why what is so, and why am I looking at a cheap, untrustworthy source of wire?

[Elf]

I always use spec grade receptacles myself, usually Pass & Seymore because that's what the local shop stocks. For switches the cheap ones seem to work ok but with receptacles it definitely makes a difference.

P&S are pretty decent. With switches I suppose I've never seen an electrical problem with the cheap ones for lighting, but the tactile aspects of the industrial ones are nice. A nice solid thunk every time you flip it and a strong spring bias to either position.

Doesn't take long to use the screw terminals but does take longer than just poking the wires in the holes and it adds up if you're building houses and installing hundreds of them.

Right. It just irks me though, I can't imagine what could possibly be less effort. Maybe stabs with some sort of insulation displacement so you don't even have to strip the wire? Self adhesive faceplates with no screw? Probably some patentable ideas there if you could convince the NFPA. I suppose it offends me because I actually take pride in the things I do and care about the end result.

Unfortunately, from what I've seen, that shoddy, minimum effort level work isn't only associated with electrical, rather all aspects of new construction...

Yes, I think that is sadly the case. Although I do see decent commercial construction a lot more often than residential construction.

Of course, my personal aesthetic is biased towards commercial. This is in my utility room downstairs:

[mfratus2001]

Perhaps I missed it, (I did miss one in the first comment) but I did not see any references to anything... if this site is for learning, post some links!

https://www.electriciancourses4u.co.uk/useful-resources/history-of-wiring-colours-cable-sheathing-bs7671/

http://wiki.diyfaq.org.uk/index.php?title=House_Wiring_for_Beginners

First of all, I had no idea that wiring in England was so complex. I suppose it has to be, with the high voltage involved.
In comparison, USA wiring is so simple, and so consistent.
We don't have zones, but I think all USA regulations now require GFI (RCD in England) outlets in bathrooms and kitchens/laundry rooms.

We have three wires in the USA - Hot, Neutral, and Ground. The ground wire is now as large as the other wires, because the last thing you want is for your ground wire to burn up. If there is a short to ground, you want the breaker to blow, not a fire. Hot and Neutral are the current-carrying wires, and Ground is for safety. Neutral connects to Ground at the breaker box. Neutral is never switched in modern wiring, although I have seen that in some older overhead light installations.

[Gyro]

First of all, I had no idea that wiring in England was so complex. I suppose it has to be, with the high voltage involved.
In comparison, USA wiring is so simple, and so consistent.

Strange how people on different sides of the pond can sometimes have such difficulty in following what those on the other side find so straightforward. To me, for instance, having to wire 240V circuits for high drain appliances and 120V for everything else seems complicated. UK /European wiring is all at the same voltage - and no specific added "high voltage" complexity related to it.

We have three wires in the USA - Hot, Neutral, and Ground. The ground wire is now as large as the other wires, because the last thing you want is for your ground wire to burn up. If there is a short to ground, you want the breaker to blow, not a fire. Hot and Neutral are the current-carrying wires, and Ground is for safety. Neutral connects to Ground at the breaker box. Neutral is never switched in modern wiring, although I have seen that in some older overhead light installations.

Exactly the same here (in terms of three wires etc). There are different grounding systems at the building supply entry point, but I think there are in the US too*. No we don't switch neutral in domestic systems either.

*EDIT: As indeed there are around the world, Ref: https://en.wikipedia.org/wiki/Earthing_system

[madires]

Strange how people on different sides of the pond can sometimes have such difficulty in following what those on the other side find so straightforward. To me, for instance, having to wire 240V circuits for high drain appliances and 120V for everything else seems complicated. UK /European wiring is all at the same voltage - and no specific added "high voltage" complexity related to it.

I think, it's simply what you're used to. BTW, we got 3-phase systems adding some complexity

[Gyro]

I was trying not to go there!  At least they're not typically domestic.

[madires]

In Germany usually any household get's 3-phase into the distribution box. You won't find IEC sockets, but the kitchen has a dedicated 3-phase junction box for the stove/oven, often also used to power a dish washer. Some home owners install an IEC socket for heavy machinery in their work shop or hobby room.

[grumpydoc]

In Germany usually any household get's 3-phase into the distribution box. You won't find IEC sockets, but the kitchen has a dedicated 3-phase junction box for the stove/oven, often also used to power a dish washer. Some home owners install an IEC socket for heavy machinery in their work shop or hobby room.

In France it's 3 phase once you go above 15kVA

[Gyro]

In a domestic property the UK you only get 3 phase if you ask (and pay through the nose!) for it. The only time you'd typically get it in a house is if you are setting up a workshop with heavy duty machine tools.


P.S.

In Germany usually any household get's 3-phase into the distribution box.... often also used to power a dish washer.

How many dishes do you guys wash??? 

[BradC]

In a domestic property the UK you only get 3 phase if you ask (and pay through the nose!) for it. The only time you'd typically get it in a house is if you are setting up a workshop with heavy duty machine tools.

They're pretty common here too. Every house I've ever lived in (7 of 'em) had 3-phase.

[Zero999]

Anyway, what's wrong with the ring circuit? So far all you've done is say you think it's bad but haven't actually said why.

The problem is not in operation, where it can potentially save copper, but in failure.  If one connection fails, all of the current flows on only one segment of the ring rather than on both paths.  There isn't any indication of a problem, so the fault can persist until it causes a fire.

1) I've never heard about a fire, due to that kind of failure.

2) Any installation can be dangerous if one connection fails, such as the earth connection.

3) One of the advantages of a ring main is if one earth connection breaks, there's still another earth connection to keep things safe.

[CatalinaWOW]

Here in the US three phase is not generally available and is an extra cost option for domestic users.

The extra cost depends on your situation.  I am in a fairly rural area, and the high voltage distribution is single phase.  There is a three phase line running along a highway a little more than a kilometer from me, so I am closer than many others in my area.  But the cost of adding a kilometer + branch of the three phase system is more than I am interested in.  If I ever develop a compelling need for three phase I'll install a rotary converter or the like.

[madires]

In Germany usually any household get's 3-phase into the distribution box.... often also used to power a dish washer.

How many dishes do you guys wash??? 

  The dish washer is connected in parallel with the stove, but just single phase. You never have enough wall sockets

[Mechatrommer]

dish washer uses electricity meh? we use the hands... our 1KW induction cooker + smoke exhaust fan over there is mainly for decoration, albeit ring sockets are provided specially for them. btw our much complicated 3 phase only goes to commercial premises. higher rate, higher rate $$$ ... i guess we need special order delivery if we want it to residential place.

[SeanB]

Germany 3 phase because you can use 4 wires of small diameter for the supply, and the load is going to be balanced down the street line, so you can use a smaller diameter neutral, as the current it has to handle is only the imbalance between phases, not the full phase current.  Thus a lower cost of copper per house supply for the same power level, plus your distribution system has a large copper saving in smaller neutrals. the inherent balancing of load is also good for the supply side, less draw on one phase with peak cooling time is balanced down the street, and all loads are not on a single phase.

UK uses ring mains, because of history, and they will not change, though the wire sizes have changed over the decades as cable insulation improved, the original cables used DCC gutta percha tinned copper, and a ring main would have been a 4mm cable, but the high temperature rise allowed on new PVC insulation means the cable size was relaxed to 2.5mm later on.

The silver wire was used in the Manhattan Project, as they needed massive electromagnets in the early isotope separators, and copper was a war resource and scarce, so the US Mint loaned them hundreds of tons of silver, which was used to make wire used to wind them. Slight power saving as it had lower resistance, and after the war the silver was returned ( which is why none ended up as museum pieces) with only a small loss from all the processing and recovery.

Wire nuts here in South Africa are not a plastic nut, but a ceramic unit with a thread formed in the inside, so you can twist the wire into them, and even in a fire they will not melt before the wire, even if they arc the cable melts first. Pretty reliable if applied right, like any other connector, and as before, differs per country.  All sockets here and switches are not allowed to be push in, you have to have a screwed clamp on the wire, though the Wago style is becoming popular for joining cables in the junctions. Preferred though is a crimped ferrule and an insulating sleeve over it, used mostly on larger cables 4mm and higher, as that is the only method allowed other than a screw connector.

Copper coated aluminium is very common, often used in windings of transformers, because it is cheaper, even if it has issues with creep and low melting point inside windings. If you have a newer microwave, new home appliance with an electric motor or any mains frequency chokes or transformers it is likely to be wound with CCA wire. A lot of the cheap premade cables are also that, or even copper coated ( hopefully) steel, or even some mystery wire of indeterminate type, most likely made from poor grade recycled metal. Buy a cheap set of jump leads and they are almost sure to be a CCA core in a very thick foamed plastic cover, so that they look like high capacity, but which are not even going to pass 10A without overheating.

[Gyro]

UK uses ring mains, because of history, and they will not change, though the wire sizes have changed over the decades as cable insulation improved, the original cables used DCC gutta percha tinned copper, and a ring main would have been a 4mm cable, but the high temperature rise allowed on new PVC insulation means the cable size was relaxed to 2.5mm later on.

I don't think so on that one actually - our old 15A round-pin sockets used to be on radial circuits, obviously back in the '20-'30s there weren't very many of them. The ring circuit came in at the same time as the 'modern' 13A square pin (fused plug) sockets iirc.

Edit: There would also have been lower rated radial circuits for the smaller 5A round-pin sockets for lamps etc. The whole thing changed to a common ring circuit when it became posible to limit fault load on appliance flexes due to the range of available fuse sizes in the 13A plug.

https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets:_British_and_related_types#BS_1363_three-pin_.28rectangular.29_plugs_and_sockets

[IanB]

Here in the US three phase is not generally available and is an extra cost option for domestic users.

The extra cost depends on your situation.  I am in a fairly rural area, and the high voltage distribution is single phase.  There is a three phase line running along a highway a little more than a kilometer from me, so I am closer than many others in my area.  But the cost of adding a kilometer + branch of the three phase system is more than I am interested in.  If I ever develop a compelling need for three phase I'll install a rotary converter or the like.

The difference in the UK is that the high voltage distribution to anything other than a single isolated house in the middle of nowhere is invariably three phase. The supply is stepped down through a three phase transformer to give a three phase low voltage supply, and the three phases are then distributed evenly between the houses fed by that transformer, one phase to any given house.

This means that most houses do have a three phase distribution cable outside in the street and a three phase supply could theoretically be provided into the house. The snag is that having more than phase present exposes the line voltage of 415 V in the supply cabinet. Electricians are usually prepared to do hot work on 240 V systems, but I think not so much on 415 V systems. (Also since the substation transformer is often large enough to supply dozens of houses the fault current capability is substantial.)

[nali]

The difference in the UK is that the high voltage distribution to anything other than a single isolated house in the middle of nowhere is invariably three phase. The supply is stepped down through a three phase transformer to give a three phase low voltage supply, and the three phases are then distributed evenly between the houses fed by that transformer, one phase to any given house.

Oddly enough, the house where I lived as a kid had 3 phases into the house. Only one of them supplied the meter the other two had no fuse or tails and were "protected" only by the crimped wire seal. I can't remember the age of the house, something like 1910-1930 IIRC.

[Zero999]

Here in the US three phase is not generally available and is an extra cost option for domestic users.

The extra cost depends on your situation.  I am in a fairly rural area, and the high voltage distribution is single phase.  There is a three phase line running along a highway a little more than a kilometer from me, so I am closer than many others in my area.  But the cost of adding a kilometer + branch of the three phase system is more than I am interested in.  If I ever develop a compelling need for three phase I'll install a rotary converter or the like.

The difference in the UK is that the high voltage distribution to anything other than a single isolated house in the middle of nowhere is invariably three phase. The supply is stepped down through a three phase transformer to give a three phase low voltage supply, and the three phases are then distributed evenly between the houses fed by that transformer, one phase to any given house.

This means that most houses do have a three phase distribution cable outside in the street and a three phase supply could theoretically be provided into the house. The snag is that having more than phase present exposes the line voltage of 415 V in the supply cabinet. Electricians are usually prepared to do hot work on 240 V systems, but I think not so much on 415 V systems. (Also since the substation transformer is often large enough to supply dozens of houses the fault current capability is substantial.)

Yes and because the fault current is so high, each house has a large, high breaking capacity fuse (normally 100A but it probably depends on the size of the property) where the cable enters the property, before the meter.

[james_s]

In the US you don't see fuses before the meter in residential situations, normally the primary of the distribution transformer on the pole or in a vault will be fused but otherwise the first protection device is the main breaker in the panel. 200A 240V service is typically standard these days though large houses may have 400A and very large houses (as in mcmansions) may have 600A service.

[Monkeh]

The ground wire is now as large as the other wires, because the last thing you want is for your ground wire to burn up. If there is a short to ground, you want the breaker to blow, not a fire.

This is entirely unnecessary, as the current required to make the conductor fail is many times greater than the current required to open the breaker either magnetically or thermally. The greater risk (as seen by our regulations, at least) is raised ground voltage during a fault leading to shock risk. This is managed by ensuring the voltage cannot raise sufficiently high to be dangerous or ensuring immediate disconnection rather than waiting for a thermal trip (using an RCD(GFCI)).

E: And I should mention that trip times of breakers are verified by measurement of the circuit, as opposed to "She'll be right".

In the US you don't see fuses before the meter in residential situations, normally the primary of the distribution transformer on the pole or in a vault will be fused but otherwise the first protection device is the main breaker in the panel. 200A 240V service is typically standard these days though large houses may have 400A and very large houses (as in mcmansions) may have 600A service.

In the UK you don't see transformers catching fire much.

[james_s]

I don't think transformers catching fire is common anywhere. I've seen it once, when the substation next to my middle school received a direct lightning strike. The transformers are fused at the primary to protect against a fault on the secondary. Not common, but neither is a fault that trips the main breaker in a house, you still need to have protection.