Hello All -
I wanted to share a recent experience with my 55g tank, APC UPS, and portable GFCI units.
First, the setup:
The APC UPS is plugged into a regular grounded wall outlet.
I have two GFCI plugs (see Amazon.com: TRC Shockshield White Portable GFCI Plug with Surge Protection 14650-021-012: Home Improvement
) plugged into the UPS, one on the battery-backed-up side, one on the surge-only side.
My heater and lights plug into the non-battery side GFCI plug, and the air pump and filter plug into the battery side GFCI plug.
I had a brief power outage today and here is where I got my surprise. As soon as the power went out, both GFCI plugs tripped off, even before the UPS battery came online.
I did some digging, and found this article:
Ground Fault Circuit Interrupters (GFCI)
which points out that portable GFCIs (like the plugs I am using, or those on extension cords) are required by code to trip if the input power to them is interrupted, and have to be manually reset. This is to prevent, for example, a table saw from suddenly coming back on in a workshop after a power failure. But this is bad for the fish - it means the UPS battery can't drive the air and filter until somebody manually flips the GFCIs. Note that GCFI wall receptacles DO NOT have this requirement, and normally do not trip during a power failure.
It does no good to plug the UPS itself into a GFCI receptacle. If a short in the tank equipment trips the GFCI, the UPS says "o, power's off, turn the battery on", and WHAM the tank equipment is re-energized - a very dangerous condition.
So what I plan to do is to buy two GFCI wall receptacles, mount them in electrical boxes with short pigtail cords, and plug them into the UPS in place of the portable GFCIs. This should give me the GFCI protection without the manual reset when input power is lost.