I'm embarking on a re-wiring of my Garage/Workshop. I've identified 3 new circuits I'm adding. I have a large roll of new 12-3 wire, which I'm looking to use up in this project. After completing the wiring I'll be insulating and covering the stud-bays.

I am thinking of running two pulls of 12-3 while I've got easy access, and leaving one of the extra hot wires unconnected (capped), in the box, for when I get around to re-doing my pantry (shares a wall) and want to add a grounded outlet. Running an extra 12-2 would mean putting another hole in each stud along the wall, and I've already got 2 holes in each (50's house with many partial-remodels), I don't really want to turn the structure into swiss cheese.

I have not been able to find anything in the code about leaving one of the wires of 12-3 unused. Do you think an inspector would balk at this? My city uses the most recent version of the NEC code.

I know a 12-3 run needs a double-pole breaker because of the shared-neutral, but what about my theoretical extra wire (with one live circuit, but will eventually require a shared neutral)? Do I just need to run the circuit and wire a dummy outlet? I'd rather not unless necessary.

  • Check out the answers from this question. It's now code to potentially have an unused wire in all switch boxes, so that's certainly not a violation.
    – JPhi1618
    Nov 30, 2015 at 22:11

4 Answers 4


There's nothing in the code that says you can't pull unused wire. In fact, since it's not technically connected to the electrical system, NEC probably doesn't apply at all.

Just keep in mind that garage receptacles will require GFCI protection, while a receptacle in a pantry would not.

  • In the case of a switch loop and the unused neutral is connected to the electrical system... Do you just put a wire nut over the single wire?
    – JPhi1618
    Nov 30, 2015 at 22:23
  • 1
    @JPhi1618 Yes. Twist-on wire connector, or any other approved termination device.
    – Tester101
    Nov 30, 2015 at 22:25

Running an extra wire is a good idea. If you have wire to "use up" considering splitting lighting and power. It is a nice thing if you trip a circuit breaker with a power tool to have the lights stay on.

  • This is a good point. I've got an existing circuit powering one light in the garage (original ungrounded romex, but I can't get to the rest of that circuit, so it get's to stay). In this case the outlets on the new light circuit are bonuses for things like battery chargers and speakers, while I have a more dedicated circuit for tools.
    – ench
    Dec 1, 2015 at 0:01

A pantry receptacle is required to be on one of the small appliance branch circuits that feed the kitchen, dining area, pantry, nook, etc. See NEC 210.52(B)(1). As long as you don't have anything else on that circuit but those areas you are within code. If you put some garage stuff on with the pantry then you are violating the code.

You are correct about the two pole breaker OR you can use an approved handle tie.

If you are running the spare conductor with a multiwire branch circuit or for future expansion the Code still applies. Just cap it with a wire nut and blank off the pantry box.

Happy Tuesday!


Instead of running 2 circuits from your panel inside the house, I'd run a single, larger gauge cable (8-3 ga 40A or 10-3ga 30A) and install a sub breaker box in the garage.

Run the local circuits from sub box.. adding more circuits is a simple task.

Resetting tripped breakers is a lot easier than going back into the house.

  • This is good general advice, but in this case the panel is already in the garage. I'm running the new circuits from one corner to the other through an open exterior wall that I am finishing.
    – ench
    Dec 7, 2015 at 7:25
  • Thats good to know
    – HerrBag
    Dec 7, 2015 at 14:21

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