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Over here in Europe, a common approach to GFCI (RCD) protection is to have one (three-phase) 30 mA GFCI breaker as the main breaker (or something similar such as one GFCI per (sub)panel or one shared GFCI for all the outlet circuits). Per-circuit GFCI breakers are mostly seen only in new construction if you want a real fancy panel. GFCI sockets are not a thing here.

The main advantage of this solution (apart from being cheaper) is that it's trivial to retrofit to older houses without having to disentangle all the neutrals first. One could also say that it's safer, because it forces people to actually fix the fridge that trips the GFCI instead of removing the GFCI. (The main breaker can't be replaced without calling in the utility company, which would obviously take a dim view of removing mandatory protection.)

However, my impression is that such a central GFCI setup is completely unheard of in the US. Is it so? Does the NEC theoretically allow such a solution? Do some homeowners go for it anyway to save a couple hundred bucks on GFCI breakers?

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  • It won't get you out of needing GFCI's on circuits, since the current limit is too high on those whole-house jobs. For US/Canada 120V circuits, you can generally save a pile of money on "GFCI Breakers" by simply installing a single GFCI as the first device on the circuit for far lower cost, and meeting the required protection as well. 240 and MWBC you are stuck with expensive breakers, as far as I know. – Ecnerwal Mar 23 '20 at 11:34
  • Found a document (Searched for "Electrocution UK", yet the "national statistics" seem to be "nationalized" to the point that it specifies "persons normally residing in the bounds of England not the UK as a whole) which shows 7 deaths by electrocution at home in 2017. I don't know how universally retrofitted the RCD's are (i.e. are there likely to still be many older homes without them?) and the document does not detail if they were or were not present, as it's a very basic "number of deaths by age cohort / location / year" statistic. – Ecnerwal Mar 23 '20 at 11:51
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The protections do totally different things

Seriously, you do not understand the purpose of RCDs in Europe. All our attempts to make electricity safer are based on compromises between what is possible and what is affordable/implementable. These are greatly swayed by accident data which tells what kinds of accidents actually happen there. Which in turn reflects on housing stock and culture.

  • Parallel arc-fault protection is about arcing faults between Hot-Neutral, Hot-Ground or Neutral-Ground, which make heat.
  • Series arc-fault protection is about arcing faults inside an intended connection on a hot or neutral wire, which make heat.
  • Ground fault protection is about wayward (residual) current returning through some alternate current path, e.g. a human.

Europe's goal is to as cheaply as possible provide parallel arc-fault protection... while providing some very limited degree of personnel anti-shock protection.

America's goal is to protect human lives from electrical shock where small-appliance receptacle outlets are near water. Arc fault protection doesn't even enter into it. GFCIs are usually in the wrong location to provide any sort of effective arc-fault protection; but they provide excellent parallel H-G and N-G protection (and none at all for H-N). Arc-fault will come later as a separate initiative.

Let's try it Europe's way

You can put American, human rated GFCI on a whole-house if you really want to. Easy enough; just get a 60A GCCI spa subpanel and power a larger subpanel from that. 60A@240V is large enough for every load in an American house except the fixed 240V ones like water heater, A/C, EVSE, range, electric dryer, etc. Spa panels are about the price of a 2-pole GFCI breaker, so you won. Congrats.

snap

Wow, all your lights went out. What happened?

Well, you know those six smart switches you insisted on installing on your old switch loops, where they had separate green and bare wires, and the instructions said put the green on neutral if you have it, otherwise put it on ground? Each of those returns 0.5 ma on ground. Your bathroom fan, that has a 0.4 ma leak to ground. Your cheap PC power supply has a 0.9 ma leak. The coffee maker, 0.4 ma. The fridge, 1.5 ma.

"But wait. I have these exact same appliances in Chateau TooTea in France. Why don't they trip the RCD there???"

Since US breakers are focused on human safety, they trip at 5 milliamps. Europe only is after parallel arc faults, so they threshold at 30 milliamps, precisely so these numerous micro-faults do not "stack" to cause the RCD to constantly nuisance-trip. 30ma gives enough headroom that such trips aren't a problem. The downside is it sucks at human safety.

"But they're spread out! There isn't more than 2ma on any one------ Oh... right. Curse my whole-house GFCI!"

... And that's why Americans use per-circuit GFCIs. It allows our detection threshold to be low enough to protect humans.

Alright, lesson learned, let's try a 30ma whole-house

Yeah, that would actually work, but it would work in the European way, being a watch dog for H-G and N-G arc faults in in-house wiring.

Now one problem in American homes is that you have a few very large appliances that don't really benefit from GFCI or AFCI if they're grounded - range, A/C, water heater, dryer, EVSE, electric emergency heat on heat pumps, etc. If you recall before, I excluded them from the 60A GFCI panel because they're too big - they'd gobble up the GFCI capacity without benefiting from it. So I'd recommend doing the exact same thing here.

OK, what did this buy you?

  • Very weak GFCI protection on the circuits that don't already have it
  • Parallel H-G and N-G arc fault protection
  • No H-N parallel arc fault protection
  • No series arc fault protection.

For a grandfathered house that will not have per-circuit Combination AFCI protection anytime soon, would that be an improvement? Sure.

For a modern house with 2017 tier GFCI+AFCI protection, probably a complete waste.

Dat wascally wefwigewatah

One could also say that it's safer, because it forces people to actually fix the fridge that trips the GFCI instead of removing the GFCI.

How is it safer exactly? What a silly thing to worry about.

Mind you, you must consider perspective: Americans are after human safety, where GFCI'ing a grounded fridge accomplishes nothing. In the European perspective, it reduces fires caused by >30ma parallel arc faults on the wiring to the fridge, or inside the fridge. Which is a thing that could actually happen. And, the ordinary fridge ground faults that vex Americans are almost never over 30ma. So they would never trip a European home at all.

Keep in mind, when you hear about fridges tripping GFCIs, the fridge may not be faulting at 5ma. It may be on the same circuit with that coffee grinder, those two smart switches, etc. which all stack to 5ma.

The main advantage of this solution (apart from being cheaper) is that it's trivial to retrofit to older houses without having to disentangle all the neutrals first.

They're not supposed to be entangled in the first place. And one thing you'll hear me say a lot (to newbs) about GFCI receps is "Stop using LOAD. Seriously. For wizards only." And the reason I say that is so novices can avoid issues with the downline, such as ground-faulting hardwired appliances and crossed neutrals that the novice is really not prepared to fix. It would be marvelous if everything got fixed 100%, but that is not going to happen.

Also the vast majority of so-called "entanglements" are actually intentional multi-wire branch circuits. Those are fine. They need 2-pole AFCI (in most cases) and either 2-pole GFCI or per-receptacle GFCI.

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Could an RCD be used in the US for ground fault protection NO! I give 2 reasons as explained by the Code panel in the code handbook. Code in the US for feeders and ground fault protection 215.9 this refers to 210.8 , although not a code enforceable statement the code handbook (code explanation by the people that write the code) state GFCI protection for personal operate at 4-6 milliamperes with trip levels of 5 milliamperes. Equipment ground fault protection of 6-50 milliamperes 426.28 is allowed for equipment.

In the explanation of 426.28 specifies this is for fire protection not personal protection so a level higher than 5 ma would not be allowed.

Could you protect an entire home with a 5ma double pole GFCI , if they make one the minimum size for a whole house would be 100 amp (the largest I can remember or find for split 240v is 50/60a) in theory you could because every circuit would be protected but I doubt you would be able to keep it reset long enough at this level just look at all the single device nuisance trips for fans, and refrigerators. So in theory yes but in reality No because it would have to be 100 amp at 5 ma to be a whole house system like the RCD.

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  • From a practical perspective, setting Code aside for a bit, I don't think I'd want my entire house protected by a single, main GFCI breaker even if they were available in the right ampacity. Wouldn't that plunge the entire house into darkness? And what about the inrush current starting everything up again at once? And what if I were gone on vacation for a while, say during the winter, and it trips? No heat, possibly frozen pipes. If during the summer, fridge and freezer would loose power and ruin food. Sounds like a bad idea to me, even if code legal. – George Anderson Mar 23 '20 at 14:54
  • @george Anderson I basically agree and with all the replacements I have done for folks that are afraid of electrical it would be an even larger expense. I am glad my state exempts sections of the code for refrigerators & freezers. I have had customers ask for GFCI’s because they are safe , they don’t care about the cost, after loss of a freezer full of fresh elk one customer wanted me to take them all out, I could only remove the ones code allowed since they were now existing. He was not happy and even called our local building code department, I got a call with an atta boy. – Ed Beal Mar 23 '20 at 16:07
  • I am concerned about the 2020 code where practically everything needs to be ground fault protected and most things arc-fault protected as well. This is going to get worse. I suspect ppl will swap breakers on their own to avoid food losses. – George Anderson Mar 23 '20 at 16:12
  • It was there in the 17 code but my state exempted refrigerators and freezers (large items not easily moved or known to have problems with) paraphrased version of corse. – Ed Beal Mar 23 '20 at 16:20
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Additional GFCIs in the panels are not forbidden, but the outlet-GFCIs seem to be an easy and popular update.

Of course, Neutral and Ground must always be separated upstream of the first GFCI, and must not be combined anywhere downstream. Sometimes this would cause an expensive re-wiring.

The star-like concept of Neutral/Grounding (TN-C-S) has also advantages in the context of RFI, humming loops, lighting strokes.

There are even GFCIs that can be cascaded with according delay times.

But since the currents are much higher in the US,
the panel GFCI would be very bulky and/or expensive.

In Europe, the outlet volume in brick or concrete walls are more difficult to be expanded for more space.

The main disadvantage of not having panel-GFCIs is the protection gap in the cables between panels and outlets, since rodents or hanging pictures onto the wall etc. could damage the European NYM-cables and could start fires. Since the Protection Earth (PE) in the cable will be most likely also damaged, the probability to get more then 30mA PE current is very high. So the GFCI will trip long before a high product of fire-starting (short-) current times seconds will appear.

According statistics, the GFCIs in Europe do mainly prevent fires, electrocution is only the second-placed danger.

In some locations it is standard to run the wires inside metal conduits which provides much more physical protection.

In theory, the lower threshold in the GFCI-outlets (ca. 6mA instead of ca. 30mA) provides a better protection, but it's relevance was and is under discussion.

On the other hand some appliances/devices do already have some ground current during normal operation, f.e. via X-capacitors, PI-filters, windings etc. resulting in problems if freezers or heating systems are cut off because of this high sensivity. In most codes, these cases are exceptions where GFCIs are not mandatory.

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  • @statueuphemism Thanks for the hint, corrected it. – xeeka Mar 23 '20 at 10:04
  • The GFCIs for fire protection used to be >100 mA ones. However, this 30 mA threshold was only introduced in the last few decades specifically to prevent electrocution. – TooTea Mar 23 '20 at 10:09
  • As a former reasonably well-educated in the specifics of the subject due to the nature of my work high voltage lab worker - 30 mA is about 3 times too high to "prevent electrocution" The most hazardous realm is between 10 mA and 1000 mA – Ecnerwal Mar 23 '20 at 11:25
  • @Ecnerwal but much better than no protection at all - and I have tested a few of those 30mA ELCB’s by accident myself ... So glad they were fitted and working. – Solar Mike Mar 23 '20 at 11:38
  • @Ecnerwal Important is the product of current times time, see IEC publication 60479-1 for hand-feet path. Even 100micro Ampere could be lethal if inserted into the body. In Europe, every commercial electrician has to test/measure the current and time and to write it into a report after installing a GFCI. – xeeka Mar 23 '20 at 11:49

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