On Jun 1, 6:52*pm, wrote:
On Mon, 01 Jun 2009 17:36:57 -0400, RickMerrill





wrote:
wrote:
On Mon, 01 Jun 2009 14:36:46 -0400, RickMerrill
wrote:

wrote:
On Mon, 01 Jun 2009 11:53:32 -0400, RickMerrill
wrote:

[this has been tackled elsewhere, but not answered!]

Plug a drop light into GFCI - the light lights up!
Plug drop light into house AC - the light lights up.

Plug an extension cord into GFCI and test with
polarity tester - all is well with gnd, hot and neutral.

Plug (same) drop light into above extension cord and
the GFCI "blows" (i.e. cuts the circuit breaker).

The resistance of the extension cord only looks like a bigger drop light
bulb. So resistance is not the problem.

Plug a "cheater" into extension cord (above) and plug drop light into
the cheater (i.e. ground wire is not connected) making sure that there
are no possible ground contact points - GFCI "blows" [see above] !
So the grounding is not a problem.

When the GFCI compares the AC current in with the AV current out it is
obviously comparing similar phases (a.k.a. cycles). *Clearly any phase
shift due to capacitance in the extension cord COULD cause what we see.

- Rick

There is a concern with capacitance in the wiring tripping GFCIs but
you need a very long circuit to see it.
I suspect you have a lot of leakage in that circuit and the cord
pushes it over the edge.
There is no leakage in the circuit because a perfectly parallel outlet
behaves properly - the problem is entirely due to the cord, but why that
is I am not sure. It could be that the cord is an "el cheapo" and has
all kinds of leakage problems that don't show up until a real load is
put in it. I'm chopping it down from 25' to 6' and see what happens!

I bet the cord has a neutral to ground short in it.
or the neutral and ground are swapped
Try it with the cheater on the GFCI end but be careful of the ground
tab on the cheater. If the light doesn't work there will be 120v on
the ground tab..

There is no short in the cable. It is fine until a (small)load
is added (other than the polarity tester).

Using just 6 feet of the same cable - Blat!

Cheater has NO ground tab ;-)

Polarity tester says the wiring is correct!

Note: the wires in this cord are in parallel; the insulation is yellow.
the wires are #16.

???

If the neutral and ground are shorted you will never know until you
plug it into a GFCI and put a load on it.

That was my first thought too. And it doesn't have to be anywhere
near a complete short, just enough to amount to the milliamps needed
to trip the GFCI.

On the other hand, I vaguely remember that maybe GFCI's actually try
to put a tiny current on the downstream load line all the time to be
able to detect this type of fault without any actual load being
connected at the far end?





What happened when the 2 pin adapter was plugged into the GFCI and the
cord plugged into it?- Hide quoted text -

- Show quoted text -