wrote in message
ups.com...
A few years ago, I had my kitchen renovated. This included replacing
the old overhead light (regular bulbs) with halogen lights (the
dangling kind). Everything worked well.

Recently, I've noticed something really bizarre. When I turn on the
halogen lights, one of the GFC interrupters trips. The GFC outlet is a
few feet to the left of the light switch.
The bizarre part is that the GFC outlet is on a completely different
circuit than the halogen lights. Yes, I've tested this with the
breaker.

If I turn the light on, reset the GFC, and then turn the light off and
on quickly (1-2 second delay), the circuit doesn't trip. If I wait
longer, it trips. The transformer for the halogen obviously needs a
second or so to "power up", so this is a clue.

There are two switches for this light, on either side of the kitchen.
Both switches cause the GFC outlet to trip, so it's not the switch.
Just to make sure, I checked the switch that's closest to the outlet,
and the wiring looked OK (although for some reason, it is a 4-way
switch, despite the fact that there are only two switches for the
light)

The only thing I can think of is that the wires from both circuits run
side by side in the ceiling, and the transformer is somehow generating
a field that causes the GFC outlet to trip. Is this in the same
category as aliens-have-infestated-my-house or is this at least a
remotely plausible explanation?

I could test this theory by wiring a regular light instead of the
halogen light, and see if it still trips. Before I climb onto the
countertop, I'd like to make sure I'm going in the right direction.

Any advice greatly appreciated.

Let me throw in a wild guess. The GFI operates by passing both the hot line
and the neutral through a ferrite core along with a sensing line. If the
current is identical in both hot and neutral this little transformer has no
output as the effective primary has no current (the two lines cancel out).
If there is an imbalance because some current is leaking out a "sneak" path,
the sense line acting as the secondary of the transformer now has an output
and trips the GFI. Possibly, the rapid turn on of the high current halogens
induces either a spike on the power or neutral lines that are sufficient to
cause a trip or a radiated signal is being picked up by the sensing circuit.
Incandescents may not present the same turn on characteristics.

Of course, I could be wrong.

Charlie