I purchased a new thermostat but wasn’t sure about the wiring

This is a picture of the new thermostat with 3 wires coming out And the existing thermostat using 2 wires and a ground

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  • 1
    I'm seeing a lot of wires coming into the box, one of them is almost certainly a neutral. But I'd need to see the other end of the wire to know for sure. It would also help to pull the wires out a bit more so we can see them better.
    – Ariel
    Dec 6, 2023 at 23:16
  • Post a new photo hopefully is shows the wires better
    – owen gerig
    Dec 6, 2023 at 23:36
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    Good thing it will take 240V input, because I rather suspect the whites in here are L2, not Neutrals, and I very much doubt there's any neutrals in this box, @Ariel Most electric heaters are 240V. With no reds coming from the cables in the wall, the odds of a neutral in this box are slim-to-none. How about a picture of the breaker supplying this thermostat, Owen?
    – Ecnerwal
    Dec 6, 2023 at 23:42

1 Answer 1


You will need a connector that can take more wires for the white wires (L2). The red wire from the new thermostat goes to the white L2 wires. The two black wires go to the black wires that are currently connected to the black and red wires on your simple thermostat. You will want to confirm first which ones are the load so that they end up connected to the correct black wire.

Your existing connectors are probably solid wire only, so they will likely all need to be replaced with Wagos or wire nuts.

  • idk how to "confirm first which ones are the load" can i connect it to one, turn power on, test (if it doesnt work), turn power off, switch and test again?
    – owen gerig
    Dec 7, 2023 at 0:16
  • also is there a trick to getting that cap off the white wires?
    – owen gerig
    Dec 7, 2023 at 1:26
  • 1
    Odds are good that the red on the old 'stat is connected to the black that's load.
    – Ecnerwal
    Dec 7, 2023 at 1:31
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    I am back and forth on which one is the load side. If you have a voltage tester you can check with the power on and the 'stat off, the power will be on the feed side. It's probably safe to try them one way and swap them if they don't work. You might blow up the new 'stat but probably not. More likely it will just not work. As to getting the caps off, I always end up destroying those with pliers to remove them without damaging the wire.
    – KMJ
    Dec 7, 2023 at 3:39
  • Thank you all. It was NOT the wire that use to go to red. Tried , didn’t work, swapped it and tried again and it worked
    – owen gerig
    Dec 7, 2023 at 16:47

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