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#133079 - 04/24/02 10:09 AM U.S. vs. European ground-fault protection  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Sparky (Steve) has raised an interesting topic from another BB on the different approach taken to ground-fault protection in the U.S. and Europe.

For those of you who haven't read the other posts in this section, a very common scheme both in the U.K. & Continental Europe is to have a single GFI which feeds the main panel and thus provides ground-fault protection for the whole house.

The main GFI is most often a 100mA or 30mA type, although older ones could be up to 500mA, so they don't offer the close protection of the typical U.S. GFI on an individual circuit.

Per the original query, I've tried searching for statistics on accident rates related to this, but it seems to be quite difficult to locate anything.

The Irish Electro-Tech Council has data available for electrical fatalities analyzed in many different ways -- www.etci.ie/activities/accident.html -- but no information on whether GFI protected circuitry was concerned or not.

Comments?


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#133080 - 04/25/02 04:27 PM Re: U.S. vs. European ground-fault protection  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Paul,

Nice to see some activity here in this area. In looking at the information you provided there seems to be a lot of Outhouse related deaths there (probably not too many around these parts [Linked Image] in recent years) and I was wondering if any other type of GFCI protection is required to be in place by code that is of lower trip threshold?

Bill


#133081 - 04/26/02 07:10 AM Re: U.S. vs. European ground-fault protection  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
The IEE Regs. here now specify that outlets which are "likely" to be used to feed equipment outdoors should be provided with RCD (GFI) protection at 30mA, but there are no other requirements for lower thresholds.

Ireland has its own National Wiring Rules, so it may be different, but in general they are usually very close to British practice.

I think it may be necessary to look at some of these statistics with the local situation in mind. Ireland is mostly very rural, and has a lot of very old cottages with equally old outbuildings. Many are somewhat ramshackle (I've seen 'em!) with wiring that appears to have been cobbled together with whatever was available. I wouldn't mind betting that this accounts for a lot of the outhouse figures.

Another point on the stats: If you look at the last table (fatalities 1929 thru 2000) there seems to be a huge increase between the 1940s decade and the 1950s decade. What the table doesn't tell you is that many rural parts of Ireland had no electricity up to the 1940s. I understand they had a big "rural electrification" program after WWII.

P.S. A note for any of you confused by the geography:

The whole of the island of Ireland became part of the U.K. in 1801. The 6 counties in Northern Ireland are still part of the U.K., but the rest of Ireland (26 counties) split away in 1920 and is now the independent Republic of Ireland.

[This message has been edited by pauluk (edited 04-26-2002).]


#133082 - 04/26/02 08:49 AM Re: U.S. vs. European ground-fault protection  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Paul,

Isn't the 30mA threshold a bit high for protection of personell ?? Or are they thinking about something else?

Bill


#133083 - 04/26/02 06:35 PM Re: U.S. vs. European ground-fault protection  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Yes, 30mA is a little high for personnel protection. I think it's because the Regs. are still very much geared around the idea of a single GFI protecting the whole installation (or at least a section of it) rather than an individual branch circuit. If you go below 30mA on a whole-house GFI you start getting a lot of problems with nuisance tripping, hence the 30mA specification. Until the last few years, the main GFI was more often 100mA.

Originally, buildings with a direct ground connection via the cable or on PME (ground bonded to neutral) had no main GFI. But most rural areas just grounded the building to a local rod, and the resulting high earth-loop impedance meant that the breaker was needed as even a 5A lighting fuse couldn't clear a ground fault. (Early residential were the voltage type ELCB, as in my diagrams.)

More recently, the Regs. changed to specify a maximum disconnect time: 5 secs. for a fixed appliance, wall lights, etc. and 0.4 secs. for outlets feeding portable appliances. If normal fuses or MCBs can't clear a ground-fault in that time, then a GFI is needed. In practice, this still means that in most cases buildings on PME or solid-ground don't need one but ones grounded to a local rod do.

We can get GFIs for individual circuits, and receptacles incorporating more sensitive GFIs have started to become available, but they've yet to become widespread like the 6mA (?) branch GFI in the U.S.


#133084 - 04/27/02 06:33 PM Re: U.S. vs. European ground-fault protection  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Paul,

I heard discussion today about how someone thought that our future here (in the US) might include whole house GFCI protection (for personell) in lieu of individual 6 mA branch breakers or devices. Based on your experience, do you think that is even possible?

I am thinking that there may be enough cumulative leakage in a typical (compliant) wiring system and it's components to make "whole house" protection at our present 6 mA standard very impractical. What do you think?

Bill


#133085 - 04/28/02 08:43 AM Re: U.S. vs. European ground-fault protection  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Bill,

I agree with you entirely; a single 6mA GFI for the whole house would just not be practical.

In fact I could easily see 6mA of leakage from just a couple of aging heating elements, say a water heater or a stove-top plate. And let's not forget that more and more computer equipment is being used with filters that can easily have a couple of milliamps leakage to earth when working normally.

Even the 30mA GFIs common here now give nuisance trips in some larger installations, so the system has to be broken into sections.

It's also interesting to note the IEE's stance on over-current protection vs. earth-fault protection. For OCPD they make a big deal out of proper discrimination when selecting fuses or C/Bs, i.e. that the device nearest the fault should open first to minimize nuisance outages to the rest of the installation. But for earth-fault protection they're happy to specify a single GFI so that the whole building loses power. Go figure.


#133086 - 04/28/02 01:01 PM Re: U.S. vs. European ground-fault protection  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Paul,

My impression was that they were speaking of this as being a good thing as far as savings go because many individual components would not need to be bought and installed if one 200 A Main GFCI could protect the whole house. It didn't sound feasable to me but I didn't want to get into it.

Hey, we're still waiting to hear about France ...

[Linked Image]
Bill


#133087 - 04/28/02 03:14 PM Re: U.S. vs. European ground-fault protection  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,306
Thank you for the legwork Paul.
For the sake of continuity, the discussion sarted at the IAEI BB here concerning arc-faults and there similarity to our present GFPE ( 30ma)
As my home state of Vermont has added to the national requirements of AFCI's to the point of 1/2 the panel or more installed with them, the economical and practical outlook
( which may in fact be a national one , should 210.12 grow inclusive of more than bedrooms)
would simply be to subscribe to standards seen oversea's.
In the grand scheme of 'branch circuit' protection 30 , or even 100ma would seem to meet the same criterior sought, as long as the current practice (pun intended)of the point of use GFI protection were to be kept.
The stat's would , of course, play a part in the justification...as Davey S. is questioning here
[Linked Image]


#133088 - 04/28/02 03:56 PM Re: U.S. vs. European ground-fault protection  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
The economics certainly will play a big part. The situation here was influenced by the fact that originally the GFI was needed not specifically for personnel protection but simply to ensure that a direct line-to-ground short would be cleared on the systems using a local ground rod where the loop impedance could be 200 ohms or more.

Even with only the 4 to 6 circuits typically used in homes here, it would have meant a much larger installation cost to provide a separate GFI for each circuit. Even today, individual branch GFIs are expensive. To take an example, in one current catalog I've looked up a 16A Wylex breaker (a common make here). The regular MCB is priced £6.78, but the RCD (GFI) version is £43.85. [Linked Image]

If they became more widely used, then I'm sure the price would come down, just as it has done with regular MCBs, but of course we're in a vicious circle in that people won't start using them more until the price drops.

I don't like the whole-house GFI approach, for the same reason that I wouldn't like my car to be completely shut down in the middle of nowhere just because a turn-signal light has blown.

I would much prefer to see PME more widely used, although as other ECN discussions show the issue of bonding ground to neutral raises its own queries.

Bill,
There's not a lot to tell about France really. I'm holding off and staying here a while longer at the moment, as real estate prices here are rising rapidly, so with some fixing up I should have more money available when I come to sell later.

The Charente/Dordogne region in France where I went is really lovely. Mostly very rural, nice countryside, and weather that's comfortably warmer than England without being too hot.

I'll probably head back down there eventually and find a fixer upper, or maybe even get a piece of land and build from scratch.

Know anyone who knows anything about wiring a house? [Linked Image]



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