Trying to figure out if the electric installation is up to code at my place.

There are two electric circuits :

  1. The first one feeds the electric heaters in the living room
  2. The second one feeds the electric heaters in the bedrooms AND allows the thermostat to work

The thermostat controls all the heaters. Either everything heats, or nothing does (unless I switch the 1. on the electric panel). It's an older model which doesn't seem smart at all, just a knob. I doubt it "controls" another switch on the first circuit.

It feels like this thermostat controls both circuits, which isn't up to code if I understand correctly?

Does it sound like a legit installation?

Would it be easy to update a more advanced/smart thermostat that would allow us to control the two areas separately, or even better, each room separately ?

  • 3
    There are multiple types of thermostats and controls and at this point all guesses. Model #s, picture of thermostat, picture of wiring going to thermostat (if you can safely get a picture - be very careful if there is any chance of 120V or 240V wiring at the thermostat) would all help to figure this out. Jul 3, 2022 at 21:24
  • 2
    What make and model is your thermostat? Can you turn both breakers off, then post photos showing how the thermostat is wired? Jul 3, 2022 at 22:17
  • Relays could accomplish that, it would be odd and barring some unknown reasons it would be unnecessarily complicated. I would be very careful troubleshooting this, there is potential that somebody has replaced 240v heaters with 120v heaters, and used some series connection, ground wire as a neutral, or other chicanery. Also 2 single- pole (120v) or 2 two-pole (240v) breakers? Jul 4, 2022 at 14:00

2 Answers 2


Sure. Relays allow that sort of thing to happen, utterly legit to code. Most likely (but not guaranteed) how yours are run. The transformer for the thermostat would appear to be on circuit 2 based on the described behavior. It could also be (but is less likely to be) a line voltage coil relay, rather than a low-voltage coil relay.

While most people assume that all electric-resistance heat is controlled by line voltage thermostats (and a lot is) it's entirely possible to have a 24VAC (typical) thermostat that controls relays that control the heater circuits. I've lived in a place that had at least 3 circuits dedicated to one thermostat.

You can change that arrangement easily enough if you want to, though what you really should consider is changing from expensive to operate "toaster" heat to inexpensive to operate mini-split heat pump in a version suitably cold-climate for your location (or up the purchase price even more for ground-source...with even lower running cost, but it will take a long time to pay back the difference in installation cost.)


Sounds fine to me.

I mean, I am a bit surprised to hear of an electric resistance heater being controlled by a thermostat on a different circuit. Generally to keep things simple/cheap, resistance heater thermostats directly switch the 240V, which is a little nuts, and tends to throw the thermostat out of calibration from all that current heating up the internal wires within the thermostat.

Having a 240V "direct" thermostat switch a second circuit could be done (rather badly) by using a 2-pole thermostat, however the vast majority of 2-pole thermostats don't thermally switch both poles; only one switches at temperature and the other is simply an on/off switch. So that usually will not work.

The more sensible way would be by using relays.

This could be a 240V-coil relay simply in parallel with the heater on circuit 2, so it closes (activates) circuit 1 when circuit 2's thermostat calls for heat. You would hear a "click" when the relay comes on.

This could also be a mildly more sophisticated but much more versatile 24 volt system. Here, a common 24 volt thermostat transformer feeds the thermostat. Then, 24V-coil relays are used on both the heaters on circuit 1 and circuit 2 to switch those heaters on/off.

This last system is quite lovely if you have it, because it allows use of the huge variety of 24V thermostats intended for gas furnaces, from a $15 Honeywell clear up to the Nest.

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