In Sweden GFCI's are required by law to protect the whole wiring (since the first of July 2000) in all new constructed residential houses, schools, day-cares, temporary installations and things like that. Before that (since 1996) it was required in new constructed/renovated bathrooms, Garages, to protect electrical heating in floors, new installed sockets placed outside. Even sockets placed inside which could be used to feed electrical machines outside (lawn-mowers and such) should be protected. Many people however chooses to install GFCI’s in their “old houses” just to be on the safe side even if it’s not required by the code.
Re: Non-US Visitors - A Question?#3426 08/18/0103:48 PM08/18/0103:48 PM
The development of the use of GFCIs in the U.K. is tied up with the different methods of earthing used, so if you'll forgive me rambling for a while I'll explain.
First, I should point out that we don't have combined neutral/ground busbars here; the neutral is kept separate throughout a customer's installation. Three main methods of grounding are in use.
Older wiring in many towns used armored underground service cables, with the armor securely grounded at the supply xfmr along with the neutral (Note that this is the ONLY place the neutral was grounded). The main earth busbar was linked to the armor, providing an excellent path for fault currents, and no protection beyond normal branch fuses or breakers was used. Economic constraints mean that these systems haven't been installed for many, many years, but a great many are still in use in urban areas.
In more rural areas using overhead feeds, the installation is earthed to its own ground-rod. (Again, when originally installed these systems had the neutral grounded ONLY at the xfmr.) As it's difficult (and expensive!) to get the loop impedance low enough for normal fuses to be effective, an ELCB (Earth-Leakage Circuit Breaker) is fitted to protect the whole house. More about these equivalents to your GFCI later.
The third system is called PME (Protective Multiple Earthing), and is the closest we have to the normal U.S. system. In this arrangement, the utility's neutral is grounded at regular intervals along its route, and the main earth lead from the ground busbar is connected to the neutral at the service entrance. ELCBs were not normally used in the past.
Originally, PME was used only in areas where it was very difficult to get a good ground connection, but over the last 20 years its use has spread rapidly and most of our distribution network has now been converted to PME. Many houses wired on rural systems before PME still use separate ground rods and ELCBs, because PME necessitates stricter bonding requirements.
Continued next message.....
Re: Non-US Visitors - A Question?#3427 08/18/0104:47 PM08/18/0104:47 PM
The old ELCB came in two types: Voltage-operated and current-operated. For economy, most residences using an ELCB used the voltage type.
With this system the main grounding lead didn't go directly to the rod, but through a solenoid coil in the ELCB. The characteristics were such that the breaker would trip before the potential on the ground wiring of the house could exceed 40 to 50 volts. Voltage ELCBs were installed up until about the early 1970s. They're now considered obsolete, but many are still in use.
The more sophisticated current-balance ELCB operates like the GFCI, but where used in the past they were normally quite low sensitivity types compared to today. For example, my 1966 edition of the IEE Regs. specifies that a sensitivity greater than 500mA is not considered necessary except in special circumstances. Anywhere which had such high ground resistance values that a 500mA ELCB wouldn't trip would most likely have been supplied by a PME system and therefore ELCBs wouldn't be necessary.
During the last 20 years or so, earth-leakage protection has gradually increased. The current-operated ELCB got renamed twice: First it became an RCCB (Residual Current Circuit Breaker) and quite recently it was changed to RCD (Residual Current Device).
Sensitivities increased to 100mA and it has become increasingly common for an ELCB/RCCB/RCD to be fitted even when not required by IEE Regs. (such as where PME is used). Some people now use a 30mA unit to protect the whole house.
As far as the "Regs." go (not actually a legal requirement for residential, remember, but usually followed) the current edition works around specified "disconnection" times for clearing a ground fault. These are 5 seconds for lights and other fixed appliances, and 0.4 sec. for outlets which may be used to feed handheld devices. If the loop impedance is too great for a normal fuse or C/B to clear an earth fault within these times then an RCD is required.
In practice, this still usually means that no RCD is needed on PME or older armor-earthed systems, but is where a ground-rod is used.
Although not necessary for compliance, the IEE now "suggests" that a 30mA RCD be used for all kitchen outlets, outdoor sockets, and other outlets "likely to be used to feed outdoor equipment" (e.g. hedge trimmers).
Bathrooms are considered a special case by the IEE. More on that next time.
Sorry to go on so long, but you did ask for details!
Re: Non-US Visitors - A Question?#3428 08/18/0108:28 PM08/18/0108:28 PM
in Canada we must also use GFCIs in unfinished basements outside receptacles kitchen counter tops bathrooms garages crawl spaces anywhere within 1.5 meters of water sources or surfaces that commonly get wet also i went to a code seminar in 2000 held by our inspectors where they said the CEC,NEC and Europe would eventually have the basically the same code,have you herd this?
Re: Non-US Visitors - A Question?#3429 08/19/0107:10 AM08/19/0107:10 AM
We've been seeing a degree of international standardization here for about 30 years. It started in Britain in 1970 with the adoption of a common European color code for certain wiring and a change to standardized metric cable sizes.
When the 1981 edition of our IEE Wiring Regulations came out, the format was very different to that used previously, as it was completely re-written to an agreed common European layout (or so I've been informed). The new layout is much harder to follow than the old one was!
The trend toward European standardization has progressed rapidly in recent years. We're seeing our old circuit breaker rating of 5, 15 and 30A disappearing in favor of the common European ratings of 6, 16 and 32A, for example, and main switches aren't just marked "On" and "Off" anymore but also carry the European "1" and "0" symbols.
I've also heard that the IEC's aim is the whole world using the same common standard, but I think they'll have a tough time reconciling European and North American wiring practices, which are quite different in many respects.
Re: Non-US Visitors - A Question?#3430 08/19/0110:09 AM08/19/0110:09 AM
Thanks for the Details. It sounds like a service Electrician over there might have his hands full diagnosing things. And, on the older systems He could really be under pressure to find and repair faults if whole systems are going down because of it.
Does all the excess current flowing through the Earth create any particular problems? Do (does?) Cattle wear rubber shoes over there?
Re: Non-US Visitors - A Question?#3431 08/19/0110:16 AM08/19/0110:16 AM
Do you have a Neutral to Ground connection at each Building? Or is it kept separate as in one of the systems that Pauluk describes? Do you have mandatory Codes or 'Regs' that must be followed and do Electricians have to be Licensed or Certified over there?
Sorry for all the Questions, just trying to get a picture of things over there.
Re: Non-US Visitors - A Question?#3432 08/19/0110:31 AM08/19/0110:31 AM
Thanks for responding. Your (Canadian) GFCI requirements sound similar to ours. I assume that we are also using similar types of Electrical systems and devices. I've not heard plans of a common code between Us, but it sounds like it could be down the road somewhere.
Re: Non-US Visitors - A Question?#3433 08/19/0112:16 PM08/19/0112:16 PM
The problem of a ground-fault taking out the supply to everything is probably the biggest drawback of the whole-house ELCB. Some new systems are now using a "split-load consumer unit" with the RCD/GFI protecting most circuits but pre-GFI circuits for lights, and sometimes for things such as fridgs and freezers.
Obviously where a GFI is required for all circuits (i.e. most buildings with their own ground rod) the only way to implement a split-load system is to use two separate GFIs. Easy enough to install, but not cheap.
The biggest problem with stray ground currents was/is with the older voltage-type ELCB and parallel earth paths desensitizing the device. For example, the water pipes in the house would be conneced to the house ground wiring, so it was important to install the ground rod far enough away that its ground resistance gradient didn't overlap with that of any buried water service pipe.
Another problem where houses are close (quite common in our relatively crowded land) is that a ground fault on one house could trip the ELCB on a neighboring house if the two ground rods were too close.
Fortunately, these problems are gradually disappearing as the older type ELCBs are taken out of service.