GFCI

Our house is 7 years old and there's a GFCI outlet (always on)
installed in our garage. I wanted to tap into the GFCI outlet to have
electricity for the new fluorescent lights I installed in the garage.
I didn't want to tear up the drywall so all I did was take an old
heavy duty extension cord and cut-off the female side, stripped the
wires and connect to the new outlet and plugged the male side of the
extension cord to the GFCI outlet. After doing so, I tested to see if
the new outlet would provide power and it did, also checking with a
tester and everything was ok. I then proceeded to connect the new
outlet to the switch (middle of the run) that controls the fluorescent
lights using 14/2 NM gauge wiring. Every step of the way, I made sure
the wiring was done properly by using the tester. Now after all this
was done, I plugged the extension cord to the GFCI outlet and turned
on the lights using the switch. And long behold, I have light in the
garage.
However, once in a while (and it seems to be random), when I turn-off
the lights using the switch, the GFCI would trip. Then I would have
to reset and all is well again. I read in previous posting (back in
2000), someone had a similar problem, but his GFCI was tripping when
the lights were turned on. And it would seem that if I did the wiring
incorrectly, the GFCI would also trip when I turn on the lights NOT
when I turn them off. And again, it would be random. Also, to check
if the extension cord was the culprit, I changed the wiring using 14/2
NM gauge, and the problem still exists. What did I do wrong? Is the
GFCI that sensitive to detect a very small variance?

Thanks.

 

Did you use a new switch? Sounds like some voltage is draining to ground...

Mike

 

Mike,

Thanks for the reply. Yes I did, but if some voltage is draining to
ground, wouldn't that indicate that the switch is not properly
grounded? But when I tested the wiring with a tester, all seems to be
ok. I've read from other postings that it's not really recommended
connecting fluorescent lights in the same GFCI wiring because of the
ballast or something like that.

 

Here's an interesting post with a guy that never experienced a GFCI trip
with all sorts of appliances, including fluorescent fixtures:
http://fins.actwin.com/aquatic-plants/month.200205/msg00752.html

To answer your question: if voltage is draining to ground, you have a short
somewhere. Doesn't necessarily mean that your switch is not grounded. If you
had a bad switch that was leaking current to its metal frame, which wasn't
grounded, you'd most likely get zapped. Here's how a GFCI looks internally
(you can infer operation from this):
http://homerepair.about.com/library/graphics/gfci_schematic.jpg

I'm not too familiar with ballast internals. Sorry. Perhaps your GFCI is too
sensitive?

Mike


I have had my share of GFCI problems

 

That would have been my first guess. It's tripping on the glitch.

Try a little snubber across the switch, say 1K 1W in series with
about 1-10 nF, 600V.

Good Luck!
Rich