I have a small shed directly behind my workshop that I want to wire for outlets and lights. It will have a small a/c window unit and an electric heater. The wife is going to use this as her art studio. I have a subpanel in the workshop that has a breaker to run a 240v heater, that I no longer use ($$$). Can I wire the shed to the subpanel and can I use the breaker for the heater to do this? I have other questions but right now this is my starting point.

Update: First off, thank you to everyone that commented. I do appreciate it. After reading the comments I have new questions:

I would like to just disconnect the wire from the outlet for the current heater in the shop and run that to the she shed without having to make any changes to the subpanel. If I do the MWBC, can I do this? I would put the heater/ac on one 120 and use the other for the lights and outlets. On the GFCI outlets are you saying ALL of the outlets need to be GFCI? Last one. If this were your project, and you were going to do it yourself, walk me through how you would do it. I certainly don't want to do anything to compromise safety. Period. I realize the BEST way to accomplish this is to allow a certified electrician to do the work, however, I've had three people come out and give me quotes and their prices left my bottom jaw on the floor. That's why I'm here. Again, I do appreciate the feedback.

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    Ok, I will take some photos to add to my post. Thank you.
    – Leon Draw
    Commented Apr 27, 2023 at 14:00
  • What is the rating of the 240v breaker? If 20 amps, I believe (others smarter than me please comment) you can run 2 120 v circuits without having to bother with a sub-panel and all the rules associated with that in the shed. This could be installed as a MWBC, IF the 240 v breaker is 20 amps. Also, what are the power requirements of the heater? Commented Apr 27, 2023 at 14:27
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    @manassehkatz-Moving2Codidact I believe you can run 2 120v 20amp circuits to an out building w/o needing to bother with a sub-panel and additional ground rods. But ,yes, a lot of it depends upon the anticipated loads. Commented Apr 27, 2023 at 18:32
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    @Harper-ReinstateMonica fun riff, they make a 20/20 quad HomeLine so if the load calculation supports it there could be a 20A for shed outlets and lighting, 20A for a mini split, and 20A to keep using the wire in the current shop for another tool outlet or similar. And nothing but the wire and devices needed to the shed, since it's one circuit at 120V and one at 240V.
    – KMJ
    Commented Apr 27, 2023 at 21:49
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    @LeonDraw -- are you trying to reuse the existing circuit wiring, or just the existing breaker positions? Commented Apr 28, 2023 at 1:56

1 Answer 1


The problem is, heater circuits use the two "hot" wires in our split-phase power - they don't need neutral, and she-sheds do need neutral for 120V loads.

So almost certainly, your heater circuit is done with "/2+ground" cable, with the white wire marked with tape to indicate its use as a hot wire (at least it should be marked).

Go into the subpanel and move the white wire from the breaker to the neutral bar, and remove the black or red tape from both ends, since it's now being used as neutral again. Now it's a regular 120V circuit, and you can extend it using appropriate wire (NM cable is not allowed outdoors or underground, not even in conduit).

Because of the weird way our 240V works, you can just leave the hot wire on the 240V/20A breaker - don't change it, because then you'll have a gaping hole in the front of the panel, and that's not allowed.

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    It is not at all clear to me that the user is trying to repurpose the existing wire/cable (which you answer) vs. simply trying to reuse the breaker (and more importantly the spaces in the subpanel). Commented Apr 27, 2023 at 21:02
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    You are correct. I simply want to unhook the wire from the heater outlet in the workshop to run to the shed for lights and outlets.
    – Leon Draw
    Commented Apr 28, 2023 at 14:33

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