Paul Burridge wrote:
Ground Fault Circuit Interruptor.

How splendid! We call them Residual Current Circuit Breakers in
England.

That may not be an accurate translation. As I understand it, the GFCI
requires a ground connection in order to operate, while the RCB does
not.

The RCB functions on the difference between the outgoing 'live' current
and the return current in the neutral. In the British house wiring
system, those two currents should be *exactly* equal, and the difference
(the 'residual current') should be zero. Any difference at all means
something's wrong - ping - you're disconnected.

A typical household RCB will trip on a 60 or 100mA difference in supply
current surges up to 60A. That's pretty good common-mode rejection!

RCDs can also be cascaded, so an even more sensitive RCD can be used to
protect an outdoor mains socket or a workbench.

We used to have something like GFCIs over here, but changed to RCDs
because RCDs still work if the entire house ground connection has
failed.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek