Why is it?

[LizStreithorst]

Why is it that any time a GFI trips in the fish room it is is always the fault of one of the fluorescent tank lights?

[Mugwump]

Ballasts getting too hot....?....older lights?

[LizStreithorst]

Brand new light.  I don't trip breakers often but when they trip it has always been a tank light that caused it.  I wish I knew why it is always the fault of a light.  l wish I had a clue.

[Mugwump]

...ghosts?...your fish room is haunted??......

[LizStreithorst]

It's not just in this fish room.  It was the same years ago when I lived in Mobile.  It's always the light!  Do we have no "Frank the Electrition" lurking here somewhere?

[Mugwump]

I looked around here....
https://www.google.com/search?q=fluorescent+light+trips+gfi&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb

It kinda confirms my thought about the ballast...plus says with fluorescent lights gfi's aren't really needed..or should be installed fewer per breaker...below is one of the responses...check others, they're similar..

.......................
Two things can cause this. You may have grounding feedback thru your nuetral somwhere. Florecent lighting uses less power than incandecent, but with all those wires to deal with, it's easy to get the hot and neutral mixed up at the ballast, cause the ballast to overheat, and that will make the GFI thermistor over heat, tripping the breaker. Either that, or you have a thermal intermittant fault in a ballast(overheating eventually causes a grounding or "closing loop"short) Turn it off, it cools off, turn it back on, works for awhile, then trips? Thermal intermittant fault in a ballast. trips immediatly? Crossed hot and nuetral going IN to the ballast.

[GraphicGr8s]

Why would a ballast heating cause a GFI to trip? It is sensing a potential difference between the hot and ground. They are sensitive though. I was working on a circuit after a switch and it tripped just because my sweating hands were touching white and ground. GFIs are not use on electric motors and appliances however because they will trip falsely.
I've got a ton of fluorescents on GFIs with none tripping. But I am not running any with a magnetic ballast.

[BillT]

GFI trip when the current flow is not equal between the hot and neutral wires.
This turns off the power when current is not going in its proscribed path (through the hot and neutrals. Alternative current flow pathways could be electrocuting you.
GFI's turn off the power much more rapidly than a breaker which has to heat up to turn off. This is another safety advantage.

Why would a ballast heating cause a GFI to trip? It is sensing a potential difference between the hot and ground. They are sensitive though. I was working on a circuit after a switch and it tripped just because my sweating hands were touching white and ground. GFIs are not use on electric motors and appliances however because they will trip falsely.
I've got a ton of fluorescents on GFIs with none tripping. But I am not running any with a magnetic ballast.

Large electric motors (or other electrical components with large coils) tend to trip GFIs because inductors can let a bunch of current in before it starts coming out the other end. This leads to a current imbalance which trips the GFI.

Any small stray currents not in the intended wires can cause tripping because the hot and neutral not no longer in balance.

Some GFIs just go bad and have to be replaced.

[GraphicGr8s]

And Bill, some electricians wire two GFIs in the same circuit. Don't know how my buddy did it when he wired up our house during construction but he did to one circuit. Kept tripping with the Christmas lights and couldn't figure out why. And of course the GFI that tripped is behind an 8' shelving unit. I think I just wired in a regular plug on the outside since the one behind the shelf is protecting the whole circuit.

[BillT]

Two GFI's in a row can be a problem. That's interesting. I'll have to check around and see if I have that somewhere.

In good quality GFI's you often get a sheet of paper with small print and wiring diagrams. They show different ways to wire them up.
Most common would be use it to only protect the sockets in the GFI, but alternatives allow other outlets wired to a single GFI in the wall to also be protected. There are also GFI's that go in a circuit breaker box and will protect a whole circuit from there.

The local ones are easier to reset, will shut down fewer things, and are easier to determine what the problem causing the tripping is since fewer things are plugged in to them.

[GraphicGr8s]

Yeah Bill that was kind of what I was alluding to. It was a problem.

If you put the GFI outlet in the beginning of a circuit it will protect the entire circuit. And it's a lot cheaper than a breaker.

IIRC the latest NEC is requiring arc fault

[EdKaz]

Why is it that any time a GFI trips in the fish room it is is always the fault of one of the fluorescent tank lights?

Any moisture build up inside the lights when they pop?

A stray droplet of water, or even excessive condensation inside the fixture may be enough to pop the GFI circuit.....ESPECIALLY with the newer electronic ballasts

[BallAquatics]

Any moisture build up inside the lights when they pop?

That would be my choice for the source of the problem as well.

Dennis

[LizStreithorst]

In my case it was moisture   My lights aren't hung I lay them across  the length of the tank.  I noticed that this one that was causing the problem was set right above the sponge filters.  I let it dry out, moved it forward a bit and all is good.  Sorry for my stupidity.

[Mugwump]

..just glad to hear that it's resolved now......