I have a gfci outlet in my basement that I installed myself. Using a
three prong outlet tester I confirmed that it was wired correctly (two
yellow lights). The reset switch on the gfci outlet also worked
correctly when tripped. Later I bought a three prong outlet tester
with the button for testing the gfci outlet. When I push the button on
this tester, the gfci does not trip but shows a red and yellow light
(hot/neutral reversed). I switched the wiring and get the same when I
push the test button. I changed the gfci outlet itself and get same
thing. I know the tester works correctly cause I tried on another
outlet I installed myself. Anyone have any idea what the problem is?
Sounds like maybe either you didn't have a ground wire to connect to
that GFCI or you had one and did so, but it really isn't connected to
ground at its other end.
Outlet testers with GFCI test function connect a high value resistor
between the hot output slot on the receptical and the ground pin hole to
simulate a leak to ground.
That's why I suspect there's something funny about the ground to that
I take it you meant "no", not "to" there...
First, though I'm not a code mavin, I'd say that kind of connection
won't be to code.
My opinion is that the tester wouldn't trip the GFCI when the "GFCI
test" was applised because the test leakage test resistance would be
connected between hot and ground, just like any other "normal" load.
But, as in many cases, "One test is worth a thousand expert opinions."
If we hook the ground wire and the neutral wire together on a GFCI
outlet, or any outlet downstream from the GFCI, the GFCI will trip when
we apply power to the circuit. You wouldn't be able to get a test from
it, it just won't work.
That's interesting. But it's not what they were asking. They were saying
if there's no ground and someone wrapped the neutral around both neutral
and ground connections on the outlet. Illegal though in one sense it's
better than no ground at all, on the other hand if that neutral ever loses
its connection while loads are connected the neutral will become hot as
will all "grounded" metal connected into such a miswired outlet.
However, if it was a GCFI outlet which is comparing current going out the
hot with current coming back on the neutral it seems like that ought to
still work sensing a difference regardless. Does it need to have a legit
ground to function? In the event of a fault it should still see more going
out the hot prong than coming back in on the neutral prong and trip.
Assume a GFCI receptacle with no circuit ground and GFCI line-neutral
connected to GFCI ground terminal. A plug-in GFCI tester connects a
resistor from hot to ground. The current would flow out the load-side
hot, through the tester, to the GFCI ground and line-side neutral. The
current does not flow through the GFCI load-side neutral so there will
be a current imballance and the plug-in tester will work. A downstream
hot-neutral connection would cause an immediate trip.
If the ground terminal was connected to the GFCI load-side neutral, the
GFCI wouldn't detect any ground-fault returned through the GFCI outlet
ground pin. A plug-in GFCI tester would not work. A downstream
hot-neutral connection would not cause a trip.
With supplied-ground, neutral, GFCI-ground and line-neutral all
connected together, it would work as in the first case above.
In all three cases a plug-in outlet tester with 3 LEDS would indicate good.
Same except load-neutral instead of line-neutral would cause an
I would say the potential hazard always outweighs possible advantage.
Yup. GFCIs don't use the ground terminal at all except to connect to the
GFCI outlet. They work correctly without a ground and can be used on
circuits without a ground (the NEC requires a label).
Ouch! Ya got me there Bud. But half a loaf is better than none.
I could try and slip out of getting the first case wrong by claiming
that if someone was enough of an "ignoranus"* to have connected ground
to neutral then there'd probably be a 50-50 chance he'd have connected
it to the load side neutral. (But I won't.)<G>
* That term means a stupid a-hole.
No, you don't know that it works correctly. Only that when you tested
it on a presumably good outlet it said it was good. The chart on the
tester alone is about 5 or 7 lines long and indicates that an outlet
can be bad in various ways, and you don't know that the tester works
in all those situations.
This is not to say the tester is broken. I'm just commenting on your
However if the tester says the hot and neutral are reversed, and then
you correctly reversed them and it still says the same thing, I think
we can say the tester doesn't work correctly all the time.
No idea, really. I only know how to criticise. :-\\
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