GFI & storms

[Doug]

Originally Posted by Lampshade

Well... there's another option too. GFCI's trip based on detecting trickle currents. They operate in 20-40 milliseconds. That is EXTREAMLY fast, 1 cycle is 16ms. A typical distribution circuit breaker operates in 2-20 cycles(depending on magnitude of the fault). and faults far down a line are generally co-ordinated to clear a fuse or a recloser first, which may take 2-3 cycles. This is still longer than the GFCI.

Pretty much, you may have had phase to ground fault in your area, raising the ground potential enough for your GFCI to pick it up. the GFCI will operate before the fault is cleared by your power company's protection.

Thats sounds like a very good explanation. Of course no idea if thats the case or not. If I may add I had several gfi,s wired into my stand for my 90g at this residence and several of the same at my previous residence. Had power blurps or complete failures in both situations and never had a gfi not restart when power came back.

[Lampshade]

Since your power was turned back on within a second or 2, it was most likly an automatic reclose that brought it back, automatic recloses are usually in place to "pop" a tree off a line, and they work. If the tree was close by your house, it may have been able to show up as ground current in your house for only a the 1-2 cycles before the fault was cleared off the power line. Usually doesn't happen since there's usually many houses fed by the same circuit, and odd's of the tree being close to enough to yours is slim.

[Lampshade]

may still be a bad GFCI, they do need to be replaced sometimes, that's jsut another option. If it's usually fine and just one isolated incident, could be something external, like the power outage location. If it keeps happening then most defintily replace it, In Manitoba i'm sure you get to test it frequently enough :P. And since you're in Manitoba could actually have been a lighting hit on the distribution system, rare out here, but more common in the prairies. That would defintily raise the ground potential.

[Lampshade]

And... just to overkill this more... Could also have been a surge protector plugged into the GFCI, they shunt excess voltage to ground, which will trip a GFCI. Lightning strike would be a surge, and sent to ground by your surge protector, through your GFCI. Good surge protector's are almost instant, something like 1/100 micorseconds.