Geoffrey S. Mendelson wrote:
Fred wrote:
I think many electrical fires could be stopped if GFCI were required on
all circuits....including faulty appliances that trip them.

AFCIs are the device intended to save the world. They trip on an arc of
about 5A (the old ones needed an arc more like 60A). For new wiring they
are generally required in a home when a GFCI is not required. The 2011
NEC may required AFCI protection when receptacles are replaced. They
also trip on a ground fault of about 30mA - not for protection of people.


Here in Israel they are required by the electric company BEFORE main breakers.

You can't get a new connection without one, and every few years there is
an advertising campaign to get people to install them in old homes.

We have 230 volt single phase service, and 230 volt 3 phase split into three
separate circuits, so we don't have the 120/240 problem in the US that
was previously discussed.


There are several systems for handling "ground" wires. The basic
interest is that "ground" wires essentially be at earth potential, and
that contact between a hot wire and ground trips a breaker.

In the US, the ground wire system is connected to earthing electrode(s)
at the building. This is likely the case in other countries as well.

The US also requires the neutral and ground be bonded at the service
disconnect. If there is a hot-to-ground short the path is ground wire to
service panel, G-N bond to neutral, service neutral back to the utility
transformer. This metal path produces a high current to trip the
breaker. The earth essentially plays no part because the resistance of
the earth path is far to high to trip a breaker.

The UK, from what I have read, has several ways to handle the "ground
system". One is to earth the neutral at the utility transformer, not
have a N-G bond at the building, and not run a ground wire with the hot
and neutral service wires. Ground faults would return through the earth
and not produce enough current to trip a breaker. I believe that these
systems require an RCD (trips on H-N current imbalance like a GFCI) as
the service breaker. The fault current through the earth does trip the
RCD. (The trip level is far higher than the 4-6mA for a GFCI.)

Could be what you have in Israel.

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bud--