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I have 3 wire ( black, white,green) 240 on a double pole breaker. White and black wire connected to breaker green to neutral bar. Want to convert to 120v single pole breaker. Which wire do I connect to new breaker? What do I do with the other wire?

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    What is the current trip limit on the current 2-pole breaker? – Jim Stewart Jun 29 at 12:06
  • 30amp. I am using #10 wire to keep the same amperage. – Arthur L De Camp Jun 29 at 12:13
  • What type of panel do you have? Do you have one main breaker that shuts off all the power to all the other breakers or do you have a split bus (aka rule of six) panel in which the 2-pole breakers (ele dryer, central a/c condensing unit, ele range, ele water heater, and a "main" are in a top section. The "main" (in my case a 60 A 2-pole) feeds all the lower 1-pole breakers for the 120 V circuits and any other 2-pole breakers that one would put there. – Jim Stewart Jun 29 at 22:31
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You don't need to change the breaker. Just move the white wire from the breaker to the neutral bar. The other half of the breaker will be unused.

And change the receptacles to NEMA L5-30 or TT30.

You cannot put normal, common NEMA 5-15 and 5-20 receptacles on a 30A breaker. In fact, 30A 120V circuits are almost useless, except for small campers using the TT30.

If you need to put common receptacles on this circuit, you must change the breaker to 20A. (or 15A if there is only one socket and it's 15A).

If you need 30A capacity but need to feed devices with standard 15/20A plugs, then you need to fit a 120V-only subpanel, with all the rules for that (e.g. if it's in an outbuilding you'll need a main shutoff and grounding rods). It can then serve 2 or more 15 or 20A circuits. In fact, that is how my house is wired.

  • If you would keep the 2-pole breaker and use it for two independent circuits, it might be inconvenient later if you ever have to switch off one of the breakers. You'd have to switch off both unless you can remove the handle tie. Seems better to just get one or a pair of 1-pole breakers. – Jim Stewart Jun 29 at 19:25
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    @JimStewart It's a $10 problem you can kick down the road, assuming a 30A breaker is in fact appropriate for the load(s). – Harper Jun 29 at 19:55
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    @JimStewart -- sometimes, switching breakers isn't the correct move, for instance if rule-of-six considerations are in play – ThreePhaseEel Jun 29 at 20:39
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    Yes, if you needed to put two 120V circuits in a Rule-of-Six area, using a 2-pole breaker is the way to go. – Harper Jun 29 at 20:46
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Neutral is always white (although white isn't always neutral)

Since you're converting this from a hot-hot-ground (240V-only) to a hot-neutral-ground (120V-only) circuit, you'll need to move the white wire to the neutral bar to serve as the new neutral. The black hot wire lands on the new breaker's load lug; make sure to have the breaker switched OFF when you are connecting/installing it, by the way, and also to use an inch-pound torque screwdriver to torque the lugs to the marked tightening torque.

  • Go get the wright breaker single 30. And the wright outlet for camper. As long as it ii ten wire should be ok. Black to brass white to silver ground to ground. And it gives you a extra spot in panel. – user101687 Jun 29 at 20:04
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Black wire would go to the new 1-pole breaker. White wire would go to the neutral bar. Green wire to the ground bar.

What receptacle do you want to use? Do you want to make this a "standard receptacle" or a special receptacle?

NEMA plugs and receptacles

What size is the conductor in this wire? If it is larger than #10, you might have trouble connecting to a standard duplex receptacle so you might pigtail on 6" long pieces of #12 copper. A 20-A receptacle would give you more flexibility for connections.

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    A special receptacle for a 120v 30a camper hook up. – Arthur L De Camp Jun 29 at 3:14

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