Re: Plug In GFCI Device Avail. ?

In article <6Gu6J$gELScCFwUS@xxxxxxxxxxxxxxxx>,
jmw@xxxxxxxxxxxxxxxxxxxxxxxxx says...
> I read in sci.electronics.design that Rich Grise <richgrise@xxxxxxxxxxx>
> wrote (in <pan.2005.04.28.17.12.18.161006@xxxxxxxxxxx>) about 'Plug In
> GFCI Device Avail. ?', on Thu, 28 Apr 2005:
>
> >Some idiot will plug it into a 3-to 2-prong adapter that they haven't
> >bothered to ground (AKA "cheater"), ergo no ground fault current, ergo
> >no protection, ergo one more dead idiot with relatives with lawyers.
>
> We don't have those in UK, and our units are not GFCIs but RCDs
> (Residual Current Detectors)- they operate on a difference in the L and
> N currents exceeding 30 mA (or 10 mA for some critical applications).

Aren't "RCD" and "GFCI" simply UKUS?

> So
> they WOULD work even if plugged into a non-grounded wall socket.
> However, they (or some of them) can also detect that condition - the
> test button doesn't work and you can't reset the breaker if it doesn't.

Why? The test button on the GFCIs, on this side of the pond, connect
the load side hot to the line side neutral through a 15M(?) resistor.
This unbalances the current transformer and the device trips. No
ground is needed for GFCIs to operate.

--
Keith
.