Hoping someone can help me with this. I have searched the whole dang internet multiple times and can’t find the answer to my question, so I am posting it here. I have added two 120V-20A circuit breakers to my panel, and ran 12/4 MC to a string of five “2-gang” boxes (the first box will host a pair of GCFI’s, different than what I drew). I’ll use commercial 20A receptacles in down-stream 2-gang boxes. Total length of the run is under 100’.
Here’s where I need help (just a review and approval if I’m good). My plan is to use:
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Black/White wires from 12/4 to power the first circuit “A” on the left side of the box.
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Red/Blue (blue taped white) wires to power the second circuit “B” on the right side of the box.
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Tie all grounds together (Line/input ground wire, 2-gang chassis, “A” outlet, “B” outlet and Load/output ground wires).
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I’ll send line power to the tops of the outlets (inputs) and take load power from the bottoms of the outlets (outputs) to feed the next box … lather, rinse, repeat. I have installed a string of 5 boxes over about 60’, but may possibly add 3 more for a total of 8 boxes within a single workshop under 100’ of 12/4.
Please see pic. It’s all surface-mounted MC and boxes, strapped with Minerallac 125 Jiffy Clip one-hole clamps with holes above the MC, and fastened within 11” of each box, 12” everywhere else. I will pull a permit and have the work inspected because I have an affinity for doing things right.
My rationale for “assuming” this is correct is that it’s how I would run 12/2 to a string of 1-gang boxes/outlets. My main confusion is whether or not I should be bonding all of the neutrals in each 2-gang box, but think it’s not required because the neutrals are all bonded together in the panel. Is there a safety requirement in the code that requires the bonding of the neutrals in each receptacle box? And if so, can you please point me to the code so I can read/learn/understand?
Thank you so much for your time and assistance with my question! I love this stuff and wish I would have chosen to become an electrician. My problem is that I’m an anal perfectionist beyond comprehension. I guess a little OCD is a good thing when dealing with electricity. 🙂
Thanks again,
Rich
you can get metal or plastic ones.
Best Answer
You gotta keep em separated!
You need to keep the neutrals separated throughout the circuit for a couple of reasons. First off, if you want to put GFCI on this, the GFCI will tell you if you cross or join the neutrals by stubbornly refusing to stay un-tripped, so keeping them separated is a good policy that way. More importantly, though, neutrals rely on being protected by the overcurrent devices of their partner hot wires, as they don't have fuses or overcurrent breakers of their own. As a result, if you tie the neutrals together, and one of them opens, you'll potentially put 40A down a 12AWG wire, which is going to get rather toasty and melty...
And yes, you have the wrong cable for the job
While reidentifying neutrals to hots in a cable works, you can't take a wire smaller than 4AWG that's not white, grey, or striped with one of those two colors and legally use it as a neutral. To be fair, if one was working under significant duress, tape-flagging a hot to a neutral is by no means the worst thing you can do, but it sounds like you'll have to order in some 12/2/2 MC and do this over.