I am running two new baseboard heaters on a 20 amp circuit, also 2 outlets on a 20 amp circuit, can I run 12/3 wire and share the same same neutral from a junction box, these are on 2 separate walls in the same room, also one of the breakers will be for the heaters, and the other for the 2 outlet units.

  • What make and model is your breaker panel? – ThreePhaseEel Dec 18 '18 at 12:42
  • Do they need GFCI or AFCI protection? Also, are you sure those heaters are 120V? Given the power draw and voltage drop, 240V heaters make a lot more sense all around, so I am surprised a baseboard heater would be built 120V. Also two baseboards sharing a 20A/120V circuit would allow only 960 watts per heater (not even 1000W), and that heat may be disappointing. Those little toy heater-fans from the big-box are 1500W. – Harper - Reinstate Monica Dec 18 '18 at 17:00

If your heaters are 120V then it's possible to use a shared neutral for the heater circuit and the receptacle circuit, as long as you follow the code rules that apply for this type of circuit. (If the heaters are 240V, there is no neutral on that circuit, and they'd have to be wired separately.)

If you haven't already done so you might want to consider whether you're better off with 240V heaters and separate wiring. Even if I didn't want 240V now, I'd wire these separately so that I had the option of converting to 204V in the future, rather than save a little wire now with the shared neutral.

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  • so can I run these two circuits on the same 12/3 wire from a double pole 20 amp breaker and tie the neutrals together in the same junction box, I guess that might be what I am trying to find out. so that the outlets would be on the black wire, the red wires would be on the red wire, and share the same neutral. I really appreciate your input on this, never tried this before and want to be more knowledgeable before I get into this, I already have the 2 baseboards, the main panel is a square d 200 amp service. the heaters are 120v, 1 650 watt, 1 750 watt – rick Dec 18 '18 at 17:05
  • Yes, you can share the same white for neutral on both circuits, you must use a double pole breaker or two adjacent single pole breakers with a handle tie, and your wiring must be done such that removing a device doesn't interrupt the neutral - in other words, pigtail the neutrals. – batsplatsterson Dec 18 '18 at 20:32

Yes you can share a neutral on a 120v circuit. This is called a multi wire branch circuit. You will need a double pole breaker or at least a handle tied pair of breakers. This is to keep the power on each circuit on opposite legs. If the breakers ended up on the same leg the neutral would be overloaded and could cause a fire. This is covered in the NEC 210.4

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  • now that I am looking at my question, I see that I may have made a mistake in my wording, and confused myself...Okay, we know I want to run two baseboard heaters, and two outlets (one attached to each heater), now the outlets are supposed to be on a circuit of there own, and heaters on a circuit of their own, would it be allowed to run 12/3 wire on a 20 amp double pole breaker to a junction box, use the red wire for the outlets, the black wire to the 120v heaters, and share the white neutral wire, I looked at the NEC 210.4, and of course they use some terms I am not familiar with..thanks again – rick Jan 15 '19 at 20:01
  • Yes you can do it that way, the double pole breaker makes sure you are on separate legs. Each leg is 180 out of phase so when the outlet is at its peak the heater will be at its minimum so the neutral is not overloaded. We can clarify any terms you may not understand. – Ed Beal Jan 15 '19 at 20:39

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