[Shop-talk] Bad breaker?

[David Scheidt]

On Sat, Feb 1, 2025 at 2:06 PM Douglas Shook <dirtbeard at gmail.com> wrote:
>
> I could misunderstand the situation, but if B&T is in place, there would be no ground at the sink for the GFI to work unless you ran a separate ground to the cold water supply line or something similar assuming it is grounded.

GFCI protection doesn't depend on the existence of a ground.  They
work by comparing the current on the hot and neutral wires.  If
they're different, it means current is not flowing through the
circuit, but is leaking somewhere, so it trips.  The NEC has a
provision that allows a GFCI to be used on circuits that were
installed with ungrounded receptacles, and allows three prong
receptacles to be installed downstream of it.  (they're required to be
labelled 'gfci protected' and 'no equipment ground', but never are.)
It's worth pointing out that a plug in gfci tester -- like the one in
most outlet testers -- won't work on a gfci if there's no ground,
because the tester leaks some current to ground; without a ground,
there's no leakage on that path.  the test button works fine, as does
the self-test features built into GFCI made in the last decade.


-- 
David Scheidt
dmscheidt at gmail.com