I have a 9kw heater I want to hook up. There is a 3x8 AWG (w/ ground) cable going to and from the heater's control panel. The cable connects to a a 40 amp breaker, with the red and black on either side and neutral connected to the neutral bus, and ground connected to the ground bar.

The diagram looks like this, presumably with the L1 L1 L2 L2 terminals taking the cable from the breaker, and the O1 O2 O3 O4 terminals taking the cable which goes out to the heater.

enter image description here

Which wires do I connect where?

  • Can you post a photo of the heater's nameplate? Commented Apr 27, 2019 at 19:50
  • i don't know what that is. this is a sauna heater btw. Commented Apr 27, 2019 at 22:10
  • Well, I don't know how your heater is designed. So here we are. Commented Apr 27, 2019 at 22:34
  • @WalrustheCat -- the heater should have a label on it that depicts how much power it draws, etc.... Commented Apr 27, 2019 at 22:36
  • @ThreePhaseEel it's 9kw as per the question. i don't see any labeling like what you're requesting. what information is missing? Commented Apr 27, 2019 at 22:52

1 Answer 1


Apparently on contacting the manufacturer you are supposed to bridge the L1s and L2s.

  • 1
    The big question is "is this a continuous load?" As if it is, then you've just overloaded a 40A branch circuit... Commented Apr 29, 2019 at 3:30
  • @ThreePhaseEel thanks i'm checking into it. what could be the consequences of these two loads sharing the same return path? Commented Apr 29, 2019 at 20:53
  • I'd expect the breaker to kick before anything particularly untoward happens to anything else, but if there's something else messed up like a bad connection, then that could give first... Commented Apr 29, 2019 at 22:21

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