GFCIs on 10/3

[KenB]

I'm wiring my pole barn with 10/3, which will make two 20A circuits available in each of several quad boxes. I have installed GFCI receptacles as the first outlets in each circuit, as shown in the diagram, but only one will activate at a time -- when I reset one, the other trips. Is this because of the shared neutral?

I'm going to try using GFCI breakers, instead, but hoped to use the outlets, since they are about 1/3 the price.


Ken

 

[Charles (in GA)]

Yes, the issue is the shared neutral (multi-wire circuit). In your case, you are required by code to use a double pole circuit breaker with the handles tied together (common trip) like that used on 240v circuits. You will probably have trouble finding a 20 amp double pole GFCI breaker, if they make one at all.

In addition, you cannot tap off your neutral like you have, from the receptacle. Code requires that the you install the circuit in such a manner that the removal of a device or receptacle will NOT interrupt the neutral. In the case of your drawing, the removal of either of the receptacles will interrupt the neutral. Best way around this is to splice the neutral with a pigtail that runs to each receptacle in a box, thus removal of the receptacle will leave wire ends hanging loose, but not interrupt the neutral.

10 gauge is overkill.

Charles

 

[mrb]

you are going about this all wrong. You need seperate neutrals downstream of the GFCI receptacles. Why are you using #10? That has to be a nightmare to work with. I would stay away from the double pole GFCI breaker (if you can find one), its going to be very expensive ($200?) and do you really want to lose all your power if its tripped? You're not supplying lighting from this are you?

 

[oleguy]

not good at drawing but this is what you need.

 

[Aceman]

This is about as hosed up as you can get.

1. You kill your box fill when you use #10, especially 3-wire.
2. You must pigtail all neutrals when using a shared neutral circuit.
3. They make double pole GFCI breakers, you're going to need one, unless you want to rewire your entire circuit.
4. Trying to attach #10 to your recep screws definitely isn't ideal. It may not even be permitted, you'd have to read the literature with the receps. You may end up pigtailing #12 to the recep.

 

[Charles (in GA)]

Stumbled into some reading on double pole GFCI breakers on Mike Holt's forum (rather old thread however). It appears that IN SOME CASES double pole GFCI breakers do not monitor line to neutral, but ONLY monitor Line to Line for ground faults. The neutral wire from the breaker to the neutral bar is to provide internal 120v (line to neutral) power for tripping of the breakers GF function.

Newer double pole GFCI breakers are more likely to be capable of monitoring the neutral and being used on a three wire or Edison multi-wire circuit.

See this Siemens brochure for information on this.

Charles

 

[KenB]

Thanks, guys, for all the tips!

Ken

 

[Brandon_K]

++ Aceman!