GFCI’s in series can cause frequent nuisance trips.
If everything is wired perfectly, this should not happen – but in the real world, it’s not all wired perfectly. (Especially if done by someone who overloaded a switch box.)
They make ‘extenders’ for nearly every size of box. Those make the box deeper, thus nearly doubling the room inside it for wiring. Of course, that will make the box stick out a bit from the wall. Also, in exterior locations, you will have to worry about making this weatherproof.
I’ll just throw in that I have several outdoor products that come with GFCIs built in to the cord, and the outdoor receptacles are GFCI also. So every time you plug one in you create this situation, and they are all UL approved. They include blowers for bounce houses, contractor’s extension cords, a pool pump, the charger for a kid’s electric car, and a sewer cleaner. Also window A/Cs which plug into an arc fault breaker in the bedroom.
Now, I am sure they are there for safety reasons in case someone plugs them into an unprotected circuit, but there is nothing in the instruction manual that mentions a problem if plugged into a GFCI. In fact if I plugged one into the extension cord it would be triple GFCI protected.
Just a guess: your spa has some normal leakage to ground. And it exceeds 5 mA. So if you plug it into a GFCI receptacle the receptacle will trip. The GFCI that is built into the spa has a higher set point (e.g. 9 mA) or the GFCI that is built into spa senses the differential current downstream from the leaky components.
May I piggy-back to ask my own question about GFCI?
Two wires from the street divide into three parallel pairs, which go to an upstairs Safe-T-Cut brand GFCI, a downstairs GFCI (same brand) and an air conditioner. (I don’t know if bypassing the GFCI for air-con is a good idea, but that’s not my question.)
The question is: Can misbehavior on the from-street lines cause GFCI to trip?
One day, the GFCI tripped repeatedly; I thought we might need a new GFCI or something, but my wife insisted that everyone was having trouble with their electricity that day and the problem was external. I didn’t believe her until I noticed the upstairs GFCI, with very little attached to it, had also tripped. And indeed after the municipal electricity was more normal, we no longer had GFCI trippings.
I do not know exactly what was wrong with the municipal power, other than that we often have significant low voltage. I do know that once several years, for a few minutes, the two wires to our house, which are supposed to be neutral and a phase, were instead two different phases! :eek: (Two of our appliances were damaged that day; neighbors also had problems.)
