Questions about 240v wall heater wiring

[Steve Meliza]

It looks like you have a single pole thermostat so you're wire it as you show in the single pole wiring or thermostat PDF that you posted. You can use NM 10/2 for the wiring, just make sure to wrap the white wire with a piece of black electrical tape at each end to indicate that it is not being used as a grounded conductor, but is now an ungrounded conductor (aka hot/live). I see no reason not to use a 30A double pole breaker over a 20A.

[Mike Kelsey]

Thanks Steve,

I have taped the white "black". Do you by chance know if it makes a difference whether the same load, lets say the "white" wire for reference, should run to both thermostats from the j-box, (hence the blacks would wire through directly to the heaters)? Since their going out in parallel not in series, with as 30A breaker I can't see where it would matter. May be I'm just over thinking this thing...

It looks like you have a single pole thermostat so you're wire it as you show in the single pole wiring or thermostat PDF that you posted. You can use NM 10/2 for the wiring, just make sure to wrap the white wire with a piece of black electrical tape at each end to indicate that it is not being used as a grounded conductor, but is now an ungrounded conductor (aka hot/live). I see no reason not to use a 30A double pole breaker over a 20A.

[Steve Meliza]

It won't matter because they are in parallel as you said, but it would be best to be consistent and put the thermostat on the same phase for both heaters.

[Josiah Bartlett]

The breaker doesn't care which leg the thermostat is on, because the the load is always across the 240V bus bars, and the current flows through both poles of the breaker no matter which heater is on and no matter which side the thermostats are on.

[Mike Kelsey]

Thanks Josiah,

The wire leads on both the thermostats & heaters are 12 gauge. Does a 30A circuit require 10 gauge even at point of contact with the device? Anyone know?

The breaker doesn't care which leg the thermostat is on, because the the load is always across the 240V bus bars, and the current flows through both poles of the breaker no matter which heater is on and no matter which side the thermostats are on.

[Don Jarvie]

I'm not an electrician but I would run the heaters on a 30a breaker even though 20 may be enough. From what I read on electric heaters is that they draw quite a bit of current, usually max current, so with both on your every close to 20 amps if not surpassing it.

[Steve Meliza]

The wire leads on both the thermostats & heaters are 12 gauge. Does a 30A circuit require 10 gauge even at point of contact with the device? Anyone know?

The #12 wire is good for up to 20A and since a heater and thermostat alone is under 20A they use #12. You will still need #10 wire for the combined load back to the breaker.