Beware of your differential circuit breakers (GFCI)!

[Monkeh]

It's a different approach. Most of the rest of the world protects circuits, not outlets - and that means the entire run of the circuit. Over here, RCD protection is required on any circuit which isn't adequately protected from mechanical damage (grounded steel conduit or buried >50mm below all surfaces - both of which are impractical in typical house construction).

The protection is the same either way. GFCI receptacles are normally installed at the start of the run so that all downstream receptacles are also protected. Of course that is not possible with a ringmain configuration which I suspect is the reason the GFCI receptacle is not typically used there.

Placing the protection at the first outlet does not protect the circuit. You still have the run back to the panel - as I said, we protect the circuit, that means the cabling as well, not just items connected at outlets. We certainly have RCD sockets:


But as mentioned, that does not fulfill the requirement to protect the circuit (in fact, there's usually no protected output as the circuit can be up to 32A).

Do you speak of connecting the outlets in a ring? Making a ring connection is common for the distribution network on low voltage and medium voltage to give redundancy, but no one does this in a house.

Oh, yes, they do. Quite intentionally.

[james_s]

Placing the protection at the first outlet does not protect the circuit. You still have the run back to the panel - as I said, we protect the circuit, that means the cabling as well, not just items connected at outlets. We certainly have

I fail to see why this is an issue, how often does one need ground fault protection of a wire that is running through a wall? As long as anything connected to the circuit is downstream of the GFCI then it is protected. In my case my house built in 1979 has a single original GFCI receptacle in the garage which feeds all of the bathroom receptacles and the one out on the back deck. The only unprotected portion of that circuit is about 8 feet of wire that runs through the wall from the panel to the GFCI receptacle. Nowhere is the unprotected cable accessible, and it's still protected from overload by the breaker in the panel. The GFCI is secondary protection and not something that should be relied on, it was only about 40 years ago that they started showing up and only around 20 years ago that they had to be used anywhere other than outdoors and in bathrooms.

[Monkeh]

Placing the protection at the first outlet does not protect the circuit. You still have the run back to the panel - as I said, we protect the circuit, that means the cabling as well, not just items connected at outlets. We certainly have

I fail to see why this is an issue, how often does one need ground fault protection of a wire that is running through a wall?

How often do idiots go poking random nails and screws into walls? The answer is all the fucking time. And when you have houses where the primary construction is brick, not timber, the odds of putting one into a cable go up.

[james_s]

Where a wire passes through a stud it is required to be protected by a nail plate, these are steel plates you nail over the stud at the point where a wire passes through it. The exception to this is if the wire is armored cable or run through metal conduit. Driving nails or screws into wires is virtually unheard of, and relying on a GFCI to protect against that situation rather than preventing it from happening is ridiculous. Not to mention GFCIs here are only used on wet location circuits, a majority of wires run through homes and businesses are not GFCI protected, there's just little reason for it.

[tautech]

Where a wire passes through a stud it is required to be protected by a nail plate, these are steel plates you nail over the stud at the point where a wire passes through it.

You make that statement like it's a universal requirement which I inform it's not, not in NZ anyway.

Driving nails or screws into wires is virtually unheard of, and relying on a GFCI to protect against that situation rather than preventing it from happening is ridiculous.

I've actually seen that happen in new builds and renovations.
 

Not to mention GFCIs here are only used on wet location circuits, a majority of wires run through homes and businesses are not GFCI protected, there's just little reason for it.

That used to be the case here in NZ but recent regs require RCD (GFCI) protection on all new builds.
Any added outlets to existing too.


I like many consider them unnecessary to knowledgeable, safe or proper use of an outlet.

[steverino]

Excuse my ignorance, and this may have been mentioned, but are all circuits in GB, Auz, Europe protected by RCDs (newer codes, of course).

[Monkeh]

Where a wire passes through a stud

Let me just stop you there and point to my concrete block walls.

[james_s]

We don't run wires directly through concrete block walls here, they must be in metal conduit or armored cable which has a flexible spiral wound steel jacket. Normally with a concrete or cinder block wall the wiring would all be done on the surface using metal conduit with individual conductors. You can only run non-metallic cable through wood studs and it must be protected by a nail plate or conduit anywhere that it passes less than a certain distance from the surface. Any situation where a hapless homeowner could potentially penetrate the cable without going to extreme efforts is a code violation, not to mention it strikes me as common sense to prevent such an incident rather than try to band-aid over it with a ground fault protector.

[Monkeh]

And won't that just look fantastic in the living room.

And with that all said, let me once again bring you back to the concept of protecting the circuit, not random pieces of it with a randomly placed device.

[tautech]

We don't run wires directly through concrete block walls here, they must be in metal conduit or armored cable which has a flexible spiral wound steel jacket. Normally with a concrete or cinder block wall the wiring would all be done on the surface using metal conduit with individual conductors. You can only run non-metallic cable through wood studs and it must be protected by a nail plate or conduit anywhere that it passes less than a certain distance from the surface. Any situation where a hapless homeowner could potentially penetrate the cable without going to extreme efforts is a code violation, not to mention it strikes me as common sense to prevent such an incident rather than try to band-aid over it with a ground fault protector.

Hell that seems like a massive overkill ! 

Here it's just in ABS electrical conduit, in concrete, surface mount (exposed) and even plastic flexy (when needed) for plant wiring and only if any of it is within 2m of reach.

[Monkeh]

We don't run wires directly through concrete block walls here, they must be in metal conduit or armored cable which has a flexible spiral wound steel jacket. Normally with a concrete or cinder block wall the wiring would all be done on the surface using metal conduit with individual conductors. You can only run non-metallic cable through wood studs and it must be protected by a nail plate or conduit anywhere that it passes less than a certain distance from the surface. Any situation where a hapless homeowner could potentially penetrate the cable without going to extreme efforts is a code violation, not to mention it strikes me as common sense to prevent such an incident rather than try to band-aid over it with a ground fault protector.

Hell that seems like a massive overkill ! 

Here it's just in ABS electrical conduit, in concrete, surface mount (exposed) and even plastic flexy (when needed) for plant wiring and only if any of it is within 2m of reach.

The yanks seem to pivot from cheap and nasty strung through the walls straight to violently industrial (dated industrial, but industrial..) overkill. Moving forwards is not really a thing except for kneejerking like AFCIs.

[james_s]

A living room made with concrete block walls would be extremely rare here, in most of North America houses are built out of wood. In the East where brick and masonry is much more common there will still be wood studded walls on the inside providing a gap for the required insulation as well as electrical and plumbing. If the gap is less than a certain width (1 7/8" from memory) then the wire must be armored cable or in conduit. The only place you'd find exposed concrete walls is in a basement or garage, and again conduit or armored cable is required for obvious reasons.

I really feel like you're arguing for the sake of arguing, or at least being willfully ignorant of the differing construction methods here and not looking at a building from a holistic standpoint. Unless you can find examples (heck even one example?) of people being electrocuted in North American by ground faults in indoor wiring due to a lack of GFCI protection. Most circuits in homes here do not have GFCI protection at all, it is only used for receptacles that are within a certain distance of a sink, tub or other water source and outdoors. In a typical home you might have 15-20 circuits, in older homes one will be GFCI protected for the bathroom receptacles and newer homes will have at least 2 more for the kitchen receptacles and any receptacle in an unoccupied basement or garage must also be GFCI protected. In about 95% of cases this is done by a GFCI receptacle at the start of the run though GFCI breakers are available they are much more expensive and typically only used in high end homes and commercial buildings. It's only used when something connected to the circuit is expected to be used in or around a water source.

It's really a non-issue, ground faults in the wiring from the panel to the receptacle are something that's so rare that if it happens at all it would be considered a crazy fluke. I mean if you've got 10-20 non-GFCI circuits who's going to worry if one more has a few feet of cable in a wall that isn't protected from a bizarre edge case? Someone is negligent enough to run un-protected cable near enough to the surface that someone could hit it by hanging a picture? That's absolute madness, it's illegal to do so, and for a very good reason. No protection device should ever be relied on to prevent injury in such a case, the cable must be physically protected, if ground fault protection is used it is secondary protection like an airbag in a car. Just because you have an airbag doesn't mean you don't bother wearing a seatbelt and just drive as carelessly as you like because you've got a device to protect you. It increases your chance of surviving an incident but it is far better to prevent the incident in the first place.

[james_s]

Hell that seems like a massive overkill ! 

Here it's just in ABS electrical conduit, in concrete, surface mount (exposed) and even plastic flexy (when needed) for plant wiring and only if any of it is within 2m of reach.

It's overkill because it's such an unusual application. In probably 99% of houses in the US built within the last 50 years all of the wiring is NM cable run through wooden studs in the walls, floors and ceilings. In most homes there will be one receptacle and a light in the garage as standard, installed in one of the wooden studded walls. In a basement most of the wiring will be run through the ceiling joists, if there is a bare concrete wall then the drop has to be protected in conduit but this is rare. If you add something after the house is built and the wire can't be run through the wall then conduit or armored cable is typically used. PVC conduit is acceptable too but not as protection from nails and screws. Wood is abundant here, our houses are built out of wood, even if the exterior is brick the interior framing is wood, that's just how it is. I've never in my life seen a house made of cinder blocks, we just don't build them like that, especially in earthquake zones here on the coast. One could argue all day which system is better, but the fact is they all work, and the whole GFCI thing is a relatively recent development, they have only existed for around 40 years and even today they are not something that one would use in the absence of water.

Regardless of all that, I cannot fathom how anyone could find it acceptable to run non-armored cable such that someone could easily run a nail through it, I mean even with the best protective devices in the world that is still negligent when providing some sort of protection is trivial, why beg for an accident? Armored flex is inexpensive, conduit and metal raceway is cheap and readily available, it's very cheap protection that prevents all manner of situations that a simple GFCI might not help with.

[Monkeh]

I gave up on a longer post.

I'm not telling you you're doing it wrong. I'm just trying to explain some of the reasons we do it differently. You're just not seeing it. All you see are stud walls. I'm trying not to knock a brick one down hitting it with my head.

[james_s]

But you were complaining about the dangers of having unprotected wiring between the panel and the GFCI, which I've been trying to explain is not an issue here because the way everything else is done here makes it extraordinarily unlikely for a situation to occur where placing the GFCI in the panel would prevent it.

For what it's worth, I prefer to have the GFCI breaker in the panel where everything is centralized rather than spread all over in individual receptacles. It's especially fun when someone manages to install two GFCI receptacles in the same run and then you get to hunt down the one hidden behind a bookcase that has tripped. When I install one I spend the extra money on the panel mounted breaker, and I also use top notch spec grade or occasionally hospital grade receptacles, they're much better quality than the cheap home center stuff you find in cookie cutter homes.

[Monkeh]

But you were complaining about the dangers of having unprotected wiring between the panel and the GFCI, which I've been trying to explain is not an issue here because the way everything else is done here makes it extraordinarily unlikely for a situation to occur where placing the GFCI in the panel would prevent it.

.. I was pointing out that as we protect circuits, and our installation methods are different, that's not a valid method for us.

[capt bullshot]

Do you speak of connecting the outlets in a ring? Making a ring connection is common for the distribution network on low voltage and medium voltage to give redundancy, but no one does this in a house.

Oh, yes, they do. Quite intentionally.

That's interesting. Where and for what reason does one wire outlets in a ring?

[helius]

After WWII there was a worldwide copper shortage. Some countries responded by installing aluminum wiring, and others used ring mains, which use less copper per outlet. The UK adopted the latter option. Hindsight indicates that ring mains were a far better and long-lived solution than aluminum wires.

[Dubbie]

Having steel armored cable in all walls here would massively massively exceed the cost of GFCIs for all the circuits.

Electrical supplies are very expensive here in NZ compared to the USA

[Shock]

So I guess there is a lesson here for the people who kept blindly recommending relying only on GFCI type devices to provide bench safety when working on mains power devices.

I believe the proper test here is performed at the outlet and not just tripping the circuit breakers at the switchboard, but repeated testing is not mandatory.

From what I have seen the UK safety standards seem quite advanced, Aust/NZ is very good we don't have fused plugs but also don't suffer from their downsides. I'm not entirely familiar with the US code but based on youtube videos existing installations seem a bit cobbled together and scary at times.

[Fred27]

My breakers are of anything a little too sensitive. When doing some electrical DIY I obviously cut off the power to the circuit I'm working on. Often when I touch the neutral the breaker will trip.

My UK wiring has a breaker for all the power circuits and then separate isolation switches for the live on each circuit. Hence I can be working on the garage (safe) but the rest of the house is powered up with the breaker protecting it.

I'm assuming (possibly incorrectly) that I'm acting as an aerial and injecting a few unexpected mA into the neutral on the "disconnected" circuit.

[HoracioDos]

There you'll find the schematic and the BOM except for a load resistor: RL. If you want to know its value you'll have to get into patreon or... use the Ohm's law

Thanks for your post. You gave me a project to play with the mains.  LOL. Don't worry I have due respect to the mains.
I usually test the differential switch and sockets with a UNI-T18D (I should ask Joe Smith if I have a suicidal conduct). It has a built in RCD test but I don't know if the RCD trips bellow 30mA or how fast it does. For a nominal 220V, I guess RL should be 4.4K according to your circuit.

[Calambres]

It depends on what current limit you want for the circuit. I opted for a 50mA panel so I used 4.7K for a 51mA limit.

 Just use Ohm's law:

220V and 50mA need a 4.4K (11W) resistor which is not standard.  Use a 4K7 / 10W resistor for 46.8mA (a bit over 10W) and you're fine.

[Calambres]

This is my GFCI tester, as promised: