I am wiring a new heat pump 50,000 btu, 208-230v ~60 hz. Plaque says 12a running current, minimum 20a circuit, max 30a.

My breaker panel for the pump is a sub panel running off the main with a 60a breaker. It currently only has a 20a circuit for the shed with one light, and one 115v receptacle, a 20a circuit for a pool light with GFI, and a 20a for the pump.

During electrician install, we asked for enough capacity to add a heater some day.

Are we good to add a 20 or 30a breaker for the new heat pump?

Am I good to just go with a double 20a with 12 gauge thn wire in a whip?

Looks like inside I'm just connecting the black and red to power and green ground. No white right? I have bare 8 awg copper to bond to the pump connector. Anything I'm missing?

  • 1
    Is there empty space for additional breakers in your 60A sub panel?
    – mjohns
    Commented Jun 29, 2015 at 14:11
  • Yes there are four spaces in the sub panel , two on each side
    – user38936
    Commented Jul 1, 2015 at 0:24

1 Answer 1


From what you have described, I see no reason why you would not have adequate space in your sub panel.

As far as wiring, you are correct in that you will have two hots (L1, L2), a ground, and no neutral.

Without seeing the spec sheet for exact numbers, I can only suggest that you take the conservative approach and wire using a double-pole 30A breaker with #10 wire. If you are using some sort of conduit then THHN will be fine, as you suggested.

Note that the NEC also defines rules for supporting conduit and whips. There is no way to answer this without knowing more about the physical setup and distances between your heat pump and sub panel.

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