The unit in question asks for 208/230 V ~ 60Hz, 1Ph as the power source. I have a 30 amp circuit breaker that used to be for a water boiler. It's a 30A 2 Pole 120/240V Type Q Breaker

The part I'm confused by is the 1 Phase, requirement on the unit, while the breaker is a two pole breaker.

Does that mean I have to have an electrician install a different type breaker or will the AC people be able to use the existing one?


AC UNIT enter image description here

BREAKER enter image description here

1 Answer 1


USA/Canada power (for most residences) is single phase. The two-pole breaker accesses 240V (or sometimes 208V) single phase between the two hots. A one-pole breaker accesses 120V single phase between one hot and Neutral, which is grounded. Thus, it is sometimes also correctly referred to as "split-phase" since the neutral is connected to a center tap on the transformer that "splits" the voltage between the two hots.

Since the breaker you have is at least 25A and not more than 40A, your AC people should be able to use it as is.

  • Ah ok so it seems the breaker is perfect for the unit. Do you have any links to learn more about single phase VS double phase? I've been trying to google but I can't find articles on it, is single phase US while double phase is a EU thing or something?
    – Amir
    Commented May 6, 2023 at 12:28
  • There is no double-phase in use in power distribution. There's single-phase and three-phase, generally. And three phase comes in at least two flavors (Delta and Wye.) But even where local distribution is three-phase, most residences (USA/Canada) only get one phase connected to them. Might try your library for a book or three on the subject. Terribly old fashioned but less likely to be dead wrong than too much of the internet, which undoubtedly has some set of idiots somewhere talking about 240V as "two-phase."
    – Ecnerwal
    Commented May 6, 2023 at 12:33
  • See: diy.stackexchange.com/a/42045/18078 for a start, though. Most (not all) of the rest of the world uses non-split single phase (220-240V hot to neutral) and in some areas connecting all 3 phases of 3-phase distribution to a residence is perfectly normal.
    – Ecnerwal
    Commented May 6, 2023 at 12:39

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