I have a dedicated 240 volt circuit that's hard wired into my air conditioning unit. The circuit has a 30 amp breaker at the main box and another 30 amp breaker on the wall next to my air conditioner. Since the main breaker box is on the opposite side of the house from the garage, another run would be price preclusive. Instead, I am considering the install of a switch (e.g. DPDT Center-Off) like the Leviton 1288:

https://www.leviton.com/en/docs/PK-93107-10-02-0D-W.pdf (see figure 3)

The goal is to keep the circuit dedicated - regardless of which load it is directed to (i.e. air conditioner OR NEMA 14-30). The NEMA 14-30 would be used in the garage for charging an electric vehicle. The air conditioning unit is outside (just on the other side of the wall).

Two questions:

  1. Does this use case violate NEC code?
  2. Is DPDT a reasonable choice for this use case?

Another answer in the forum (slightly different question) stated that it is 'more elegant' to switch the Neutral wire (since it too is a conductor). I have not been able to locate a wiring diagram depicting Neutral with a DPDT. What's the scoop?

  • I can't speak to code compliance but I see no reason that neutral need be switched. That would be like requiring a DPST switch to turn off a light bulb on both hot and neutral. – DoxyLover Jun 18 '19 at 5:03
  • I suspect that the reference to neutral in that other forum would have recommended that it be switched too (in addition to the 2 hot wires), requiring a 3PDT switch. – brhans Jun 18 '19 at 9:10
  • What wiring method was used for the existing air conditioner run? – ThreePhaseEel Jun 18 '19 at 11:40
  • 3PDT would just perform on/off. The switch needs to extend the Dedicated circuit from one load to the other. I don't understand why switching Neutral seems optional. I have not been able to identify the gauge and/or rating of Romex that was used (original in-wall wiring from circa 1995). – FixItGuy Jun 19 '19 at 1:06
  • What do you have for an EV charger, and does it really need neutral, or can it plug into a NEMA 6-30? Because your A/C circuit likely does not supply a neutral wire... – ThreePhaseEel Jun 20 '19 at 1:10