I am installing a 27K BTU Mr Cool min split (install guide) that requires a disconnect/shutoff.

I want to make sure I am correctly wiring the disconnect, as I cannot find a wiring diagram for it and there are not good instructions with it. Here is the model I am using: https://www.homedepot.com/p/Square-D-QO-60-Amp-240-Volt-7-4-kW-Non-Fuse-AC-Disconnect-QO200TRCP-QO200TRCP/202353314.

Here is how I have it wired, followed by it with the shutoff, but no mini split whip installed yet.

  1. Am I sort of an idiot (or at least wasting time & money) and I do not need the neutral?
  2. I am assuming I will just wire the mini split whip to the shutoff switch in the second picture?

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2 Answers 2


Both the mini split outdoor unit and the Square D AC disconnect don't provide a neutral connection. The circuit should be 240V. I suppose it can't hurt to have brought a neutral wire to the disconnect, but you should leave it unterminated at both ends (i.e., disconnected at both the disconnect and the panel) or remove the white wire altogether.

  • 4
    As I understand it, there is no need to have different color wires or markings for the two hots as they are functionally the same and go to the same double-breaker on the panel. Commented Dec 11, 2023 at 12:42
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    Red is a hot color, so it does not need to be "marked" as a repurposed white in a cable does (and you can't repurpose whites in conduit.) That part of this answer is blatantly incorrect.
    – Ecnerwal
    Commented Dec 11, 2023 at 14:38
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    Yes, in fact in conduit, making the 2 circuit hots different colors can get in your way later. If you ever add a second circuit, it needs to be distinct from the first one. Having both be red-black does not work at all. The only reason anyone thinks "red-black is good" is cable, but cable has a different reason: it needs to distinguish wires for switch loops, 3-phase motors, etc. Do not infer that red-black is a best practice. Commented Dec 12, 2023 at 3:39
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    Marking the wires is a good way to identify which is which if you need to do maintenance or debug later. I did think that I read in the code book that you can't have the same colour in the same circuit without some marking, but perhaps that's not the case for you. Commented Dec 12, 2023 at 3:46
  • Also technically if you added another circuit, you could just swap the colours :) use two black conductors and wrap one with red electrical tape. Commented Dec 12, 2023 at 5:15

You are correct. The white neutral is not needed. And the whip connects to the two screws on the disconnect switch.

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    The whip connects to the breaker terminals. Yes, those are normally screws, but "screws on the disconnect switch" could also mean the screws that are behind the top of the breaker, and if you connected the whip there then the disconnect wouldn't. Commented Dec 11, 2023 at 12:44
  • I referred to it as the switch because that what it is. It is NOT a breaker. Has no overcurrent protection. Square D molds it in same case as a breaker, but it's only a switch.
    – Keith
    Commented Dec 12, 2023 at 15:46
  • You are correct: In this particular instance it is purely a switch. But arguably the "whole box" is "the disconnect switch" so the terminology is super confusing. And since there are screws behind the actual switch it is even more confusing. Commented Dec 12, 2023 at 15:49

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