What should cause my GFCI to trip?

JLong80

Normally we don't get power outages, but if we do (like today) its only for a minute or less. This is the first outage we have had in quite a while, but my concern is that my GFCI tripped and had to be reset after the power came back on. This obviously would be bad if I wasn't home. I want the equipment to come back on when power is restored, and I thought that GFCIs weren't supposed to trip unless there was a grounded circuit due to water leakage.

Does this normally happen, or do I have some other problem with my setup?

nomel

A GFCI monitors the amount of current going from the hot and neutral wires. Ideally, all of the electrical current going into your pump, space heater, tv, whatever will pass between the hot and neutral wire. If everything is going as it should, the current will flow from the hot, through your pump, then into the neutral wire...the amount of current being pretty much exactly the same. Now, if someone is getting shocked, the current will flow from hot, into your pump, but now a little will also go into you and to the ground, and the rest will go to the neutral wire...so, there's a slight imbalance of current coming out of the hot wire and into the neutral...pop...your GFCI will open the circuit saving you and your fishies life.

GFCI's are very sensitive (they can detect a current different that's only 6/1000 of what a 60W light bulb uses), so, if there's something causing an incredibly slight imbalance or "noisy spike" between the the two currents, you can get a "false trip"...or your GFCI could be bad....or you could have a problem somewhere.

What do you have connected to this GFCI?

JLong80

all of my equipment is pretty new, and I don't really see any problems...

unless, this could happen as a result of running too much equipment off of one outlet??? I am currently running two T-8s, a heater, a canister filter, air pump, 2 powerheads, and 2 pumps on that outlet... but I figure that should be about normal.

nomel

Well, a GFCI isn't a circuit breaker, so it's not that you're pulling too much power...the GFCI doesn't monitor that. I had a single, brand new pump that would do the same thing half the time.

False tripping with GFCI's can happen if whatever you have connected distorts the waveform coming from the wall...and big coils of wire will do this...which is what the electromagnets in the pumps are...but I'm having trouble finding a reference for you!

Maybe there's an electrician on board...

JLong80

well, I haven't had this issue at all except for the two times that the power went out today, so I doubt its much of an issue with the equipment, unless there is a fluctuation while powering up or down.

nomel

well...that's the only time it would distort the waveform significantly...

JLong80

lol... well then I guess I'm on to something

I guess I can unplug each component individually and trip the breaker to find out which item is causing the GFCI to trip.

nomel

I'm trying to say that's it's not necessarily something wrong with your equipment. I'm saying that GFCI's can "false trip"...especially less advanced ones...and would be most likely to do so at power on when you start out with big surges of power.

"Excessive lengths of temporary wiring or long extension cords can cause ground fault leakage current to flow by captive and inductive coupling. The combined leakage current can exceed 5 ma, causing the GFCI to trip."
Harrison County Rural Electric Cooperative Nuisance Tripping

"you mention the facility has motors, pumps, compressors,
etc. and there's some implication that maybe the power
line fluctuations / noise from these may be relevant
in causing the GFI's to trip."
Ground Fault Isolation Text - Physics Forums Library

"A GFCI is subjected to tests that simulate long branch circuits. While there are no specific rules concerning the length of the circuit protected or the number of receptacles on the protected circuit, remember that the GFCI will add up all the harmless leakage currents and capacitive leakages. Under extreme circumstances, this could "preload" the GFCI and make it appear overly sensitive or, worst case, result in nuisance tripping. Therefore, you should minimize the length of circuits to the degree possible."
Think like a GFCI

I would buy a new/more advanced GFCI...otherwise...call an electrician and ask him if that's normal. Have fun.

JLong80

Thanks so much for the help, and lots of great references! looks like I've got my work cut out for me... again.