I am replacing a 240v wall a/c unit with a 120v one at my workplace. There is no main shut off at the box. Breaker is DP 20A. I would like to move the red wire to the neutral bus with the breaker off to convert this circuit. Along with replacing the outlet. Anyone see problems doing this?

  • 2
    One problem I see is that you appear to be unlicensed and doing work in a commercial setting. Is money so tight in your workplace that you can't use a professional and get everything that comes with that (insurance, warranty, etc.)? Jun 16, 2015 at 13:44
  • @AloysiusDefenestrate, where do you see that this is a commercial setting??? Jun 17, 2015 at 2:35
  • 1
    from the OP: "... at my workplace." (Though maybe I'm misunderstanding that an AC unit is simply moving from the workplace.) Jun 17, 2015 at 4:06

2 Answers 2


For anyone wanting the code reference as to why using a red (or black) conductor as a neutral is not allowed:

2014 National Electric Code

200.6 Means of Identifying Grounded Conductors.

(A) Sizes 6 AWG or Smaller. An insulated grounded conductor of 6 AWG or smaller shall be identified by one of the following means:

(1) A continuous white outer finish.

(2) A continuous gray outer finish.

(3) Three continuous white or gray stripes along the conductor's entire length on other than green insulation.

(4) Wires that have their outer covering finished to show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture shall be considered as meeting the provisions of this section.


YES! Absolutely this is a problem.

You CANNOT use a red wire for a neutral.

Unless you are in Canada and have a "heating circuit" cable with only a red and black there should definitely be a white wire present.

  • This is a dedicated circuit for the a/c. Double breaker was used as 240v before, with a black and red input. White wire runs straight thru receptacle box. This would just be an unused wire (red) if removed from breaker, and going straight to outlet, right?
    – rob
    Jun 16, 2015 at 0:45
  • Help me understand this, Petey. We run 12/2 to 240v loads all the time wiring in the black and the white. We also use the white as a carrier when wiring a light switch. A little wrap of black tape indicates. Why is it that we can't wrap a red wire with white tape to indicate it's the neutral?
    – Trout
    Jun 16, 2015 at 12:55
  • Further, I see your point that there aught to be a white wire present and that Rob should use it for this project.
    – Trout
    Jun 16, 2015 at 13:01
  • 1
    @Trout, because the codes says so. This is one of those simple "There's no logical reason to question it" types of codes. Code says you cannot use a re-identified red as a neutral, that's all. Jun 17, 2015 at 2:35

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