GFCI resetting?

[Max]

I asked this question before but it was buried in another thread so may not have been seen. What are the typical causes for a GFCI resetting immediately and all the time? To borrow from my other post, there is a radon mitigation system in our house. I think the electrcity just powers a fan and nothing else. It's on all the time. When the guys installed it they didn't wire it into a new circuit, they patched into the existing, non-GFCI basement circuit. I updated this circuit this weekend to include a GFCI at the start of the run but it reset every time until I removed the radon system from the run. Any ideas?

Thanks, Max

[Rewired]

Max:
You mean the GFCI was TRIPPING all the time correct?
The reason a GFCI will trip is when there is a difference in current of 4-5 milliamps or greater between the hot and neutral wire, which is an indication to the GFCI that a current is taking a path elsewhere to ground, a path that could be harmless such as through a grounding or bonding conductor OR a path that could be potentially fatal, such as through YOU then to ground.. In any case the GFCI will then "trip" within I think 1/25'th of a second or faster, opening BOTH the hot AND neutral lines , cutting off power and hopefully proventing injury...
Common causes for a tripped GFCI that I can think of right away are damp or wet equipment, where the water in the equipment is providing a path to ground (or you, if you happen to be the path of choice TO ground).. Sometimes though faulty wiring such as a pinched wire or poor insulation, or extremely long runs of wire could trip a GFCI Even if somehow a neutral wire of a GFCI protected circuit becomes grounded, it will trip it too..
From what you are telling me when your radon mitigation is connected, you are having the GFCI trip but when its disconnected, everything is fine, I would look for a fault of some kind ( frayed wire, pinched wire, faulty wiring, water in the equipment, bad equipment in general) from the point at where the equipment connects to the circuit, TO the equipment itself INCLUDING the equipment... The fault MUST be between those two points!!!

Hope you find the problem!!
A.D

[Max]

Thanks, Rewired. Yup, I meant TRIPPED. I'll check out the run when it's light out. I'm pissed - again - because it seems like someone has done a half-assed job. I recall reading on here that you are not supposed to wire outside and inside outlets / appliances on the same circuit, it's against code, but that's what these guys have done (the fan is outside). I actually wired up a new circuit exclusively for an outside outlet (it's GFCI) so I may just alter their work and take the power from my circuit as opposed to the inside one. In the process of doing that I will rewire it all so that would elimate any of their bad wiring. If it still TRIPS the GFCI then it sounds like an equipment malfunction. I'll need some good luck getting them to come back 2.5 years later to fix that!

[HayZee518]

An outside outlet is normally a dedicated 20 amp circuit for new construction - however, as an after thought some people just pull a hot two wire from an outlet back to back to meet the code requirement of an outside outlet. Technically it's a code violation but some inspectors breeze by it.

[kactuskid]

Some items like fans and motors have a small amount of leakage current that will cause a GFCI receptacle to trip. I'm guessing that's what's happening here. What I would suggest is that you run a new dedicated circuit for your radon mitigation system and not tap off of a circuit that you will be using elsewhere in the basement. Install the receptacle inside your home and install a simplex receptacle and not a duplex for this circuit.

You also don't want a basement refridgerator to be on a GFCI protected circuit, the compressor will trip the GFCI and that's not a good thing for your food. Here you also want a simplex receptacle installed for the fridge to plug into, not a duplex. You could possibly use the same circuit for both your fridge and the radon fan depending on the entire load of the two items.

[Max]

I don't know if this is a hack but rather than putting in a new circuit can I just make the second receptacle the GFCI and plug the fridge into the first, non-GFCI receptacle? i.e. [panel]--->[simplex receptacle]--->[GFCI]--->[duplex receptacle]. I understand that the fridge would not be protected by the GFCI but since that's the only thing that will be plugged in there it shouldn't be a problem. I'm not against fitting a new circuit but space is tight, there are already something like 28 breakers in the panel already.

Cheers, Max


Edit: also, why use simplex receptacles? Is that just to ensure that nothing else gets attached to the unprotected circuit?

[kactuskid]

Yes you could make the second receptacle a GFCI instead so the first receptacle is left unprotected for the fridge. Though it MUST be a simplex, this is so nothing else can be plugged into it and it's approved by the NEC for this application for unmovable appliances such as a fridge.

You really need to add up the total wattage load on this circuit, that means adding the fridge, the radon fan and any other loads you'll have. Make sure that you don't exceed 1800 watts on a 15 amp (14 gauge wire) circuit or 2400 watts on a 20 amp circuit(12 gauge wire). If you'll fall within these limits then you can run your radon fan from the same circuit, just make sure you tie into the LINE side of the GFCI and not the LOAD side with the branch that feeds the fan. And same as the fridge, the radon fan requires a simplex receptacle.

You might also want to consider upgrading your panel in the future since you've kinda overfilled it. A larger panel would provide you with up to 40 breakers.

[Max]

Thanks, KactusKid!

Edit: the wiring is 12/2.