Shop wiring advice

[Bunchgrass]

I'm at my wit's end trying to figure out how I'm screwing up some wiring I'm trying to run in my shop. So I've come here for some/any assistance or advice any can provide and even suffer some slams if they're not TOO personal.

Here's the picture:

Trying to put in some receptacles along the walls of my shop and figured I'd go duplex at each drop. Each receptacle/outlet within the duplex box would be on it's own 20A circuit. So I figured I could run 12/3 using one hot lead to each of the outlets. AND, in the first box closest to the panel, I would put GFC outlets to provide protection for each circuit.

But use of any outlet downstream seems to trip the GFCs ---- I've tried running a separate common for each circuit but no luck. Any help?


Thanks.

 

[wyliesdiesels]

How did u wire the neutrals?

The neutral at each outlet needs to go to the same corresponding GFCI that the hot leg on that outlet connects to.

So 12/3 wont work downstream of the GFCIs.

And you cant add a conductor to a circuit fed by a sheathed cable.

Best to use 2 12/2s downstream of the GFCIs.

 

[Warrenator]

Are you plugging the downstream outlets into the "load" terminal of your upstream GFC? (Of course you are, just checking.) Is this just on one GFC unit or is the failure happening on different units, you might have a defective one. Did you plug an outlet checker into each downstream terminal to verify the wiring was correct?

Good luck.

 

[SARG]

If you are saying you are going to run a separate length of 12-2 to each box...... never have seen that done before except when someone wants a dedicated circuit for a specific purpose.

 

[Bunchgrass]

Oops ---- I misspoke. I didn't use Romex/sheathed cable but actually ran #12 wire in conduit to the boxes (2 hots, 1 neutral, 1 ground). At first I pigtailed the neutral to serve both outlets within the box. Then I began to wonder if each needed a dedicated neutral ...... tried that. No good.

EXCEPT ---- I did use 12/3 Romex from the panel to the first junction box feeding the GFCs

I had just envisioned wiring from each GFC to its downstream outlets the same as I would if it were one GFC and a single circuit but I've now confused myself.

 

[wyliesdiesels]

Ok the 12/3 to the GFCIs is fine then.

What u need to do is make sure that the neutral on each outlet ties to the same GFCI that the hot on eah outlet goes to.

It sounds like u may have neutrals reversed somewhere and this will cause the GFCIs to trip since the loads returning on the neutrals wont match.

 

[Bunchgrass]

Will double check the neutrals (err maybe it's triple by now but screwed up is screwed up and needs fixing so away we go).

Another idea I had if I can't find and issue w/ my neutrals, was to pull the GFCs and put in standard 20A outlets and see if I trip the panel breaker(s). Then replace one standard w/ a GFC . Check again. Then the other.

 

[wyliesdiesels]

Do u have a clamp meter?

 

[pattenp]

You can't share the neutral off the load side of the GFCI outlets.

 

[dfiler2]

I had to use a 2 pole GFCI breaker, I thought that was the only way to share a neutral on a circuit like that.

 

[Dagny]

2 pole gfis are pricy. easier to run seperate neutrals

 

[dfiler2]

It was much easier to put in the gfci breaker.

 

[nadogail]

GFCI's in my humble opinion compare the current flowing through the hot lead with the current flowing through the neutral. If they do not match, the GFCI shuts down.

If the neutrals are mixed up or unevenly loaded, your currents will be unbalanced.

Other possible causes of unbalance are insulation leakage or when somebody is getting shocked.

 

[wyliesdiesels]

There could also be a neutral touching a metal box or conduit.

 

[Bunchgrass]

Not to be stupid but what's the difference between me running 2 single pole breakers out of phase versus a double pole? I'm still using 2 singles but will try a double pole when I can get to town tomorrow. Would that be the issue?

BTW --- thanks for your help. GJ is one of the best kept secrets on the internet.

 

[wyliesdiesels]

Nope.

But since youre using a MWBC(multiwire branch circuit) code requires the 2 breakers to be handle tied.

 

[checkthisout]

Oops ---- I misspoke. I didn't use Romex/sheathed cable but actually ran #12 wire in conduit to the boxes (2 hots, 1 neutral, 1 ground). At first I pigtailed the neutral to serve both outlets within the box. Then I began to wonder if each needed a dedicated neutral ...... tried that. No good.

EXCEPT ---- I did use 12/3 Romex from the panel to the first junction box feeding the GFCs

I had just envisioned wiring from each GFC to its downstream outlets the same as I would if it were one GFC and a single circuit but I've now confused myself.

Lets see here.

Heres the bottom line.

You can't share a neutral downstream of a GFCI's on an MWBC

So, if you're sharing neutrals you need two GFCI's and then you need to have dedicated neutrals running back each GFCI.

There is no benefit to using a MWBC on a GFCI circuit unless your first outlet is reaaaallllllll far away from your breaker panel, then you'll save a little bit on the costs of the wire.

 

[Bunchgrass]

There is no benefit to using a MWBC on a GFCI circuit unless your first outlet is reaaaallllllll far away from your breaker panel, then you'll save a little bit on the costs of the wire.

I appreciate your help with the neutrals but regarding the cost savings aspect, you can use the wire that you already own vs having to go buy more 12-2 as well as having left overs of both to find a home for.

 

[slow]

why not run a second neutral to the panel and 2 separate circuits?

 

[dfiler2]

Or you can install one of these made for your panel and call the project complete.

http://www.amazon.com/gp/product/B0052ME2UK/?tag=atomicindus08-20

 

[wyliesdiesels]

Or you can install one of these made for your panel and call the project complete.

http://www.amazon.com/gp/product/B0052ME2UK/?tag=atomicindus08-20

Bad idea to link to a brand of breaker when we dont know what brand of panel he has....

 

[Bunchgrass]

Thanks again ---- I just went back and started w/ 12-2 and life is good.