Rodney L. Boleyn wrote:
> 
> "James R. Wetzel" <jrwetz@sunlink.net> wrote:
> >RubatoGuy@aol.com wrote:
> >>
> >> Ron asked:
> >> >What *is* a GIFI outlet?
> >>
> >> Ground Fault Interuption Circuit (GIFC) Opps, looks like I did the accronym
> >> wrong.
> >>
> >It is really GFCI or ground fault circuit interrupter.  They can kill
> >power in 1/40th of a second and will "Trip" if there are slight current
> >changes (Or a big one).  Excellent idea.
> 
> Closer, but I still don't think this is an accurate description.  In a
> 3-wire household electrical system, the hot wire and the neutral wire
> are the normal source and sink of the electricity (since it's A/C,
> they take turns as source and sink of current).  The ground wire hangs
> around as a protective path to ground, and it's usually used for
> grounding appliance housings and such.  The ground wire is not
> actually *in* the path of the electricity flow at all.
> 
> Now, your household circuit breakers detect over-currents through the
> hot and neutral wires.  The only way a panel breaker trips on a ground
> fault is if the fault drains enough current through the hot wire to
> throw the breaker, and then only because the over-current is being
> supplied by the hot wire, not because it's being drained to ground.
> 
> But the point of a GFCI outlet is, NO current is ever really supposed
> to drain to ground.  Even a few milliamps to ground could signal that
> something is wrong.  A 20A circuit breaker isn't going to notice when
> a 5A appliance suddenly starts drawing 5.03A and draining 30mA of it
> to ground.  The GFCI outlets have sensors in them that detect even
> very small currents going down the *ground* wire, and trip the
> internal breaker regardless of what's going on with the hot and
> neutral wires.
> 
> -Rodney
Excellent description.  Just hope I don't have to be a ground wire some
day!