Very basic electrical question. I have a non-functioning double pole thermostat (wired to an electric baseboard). I'd like to replace it, but of course my breakers are not labeled. Is there any way to use a simple voltage tester to identify the circuit? (Or, does the fact that there's no neutral wire mean that you can't find a voltage drop? (Thinking back a few decades to Physics 101)) If not, what can I do?

  • 1
    I guess you're looking for a better answer than "Check the voltage, turn off a breaker, check the voltage, turn off a breaker" ?
    – JPhi1618
    Nov 13, 2019 at 20:45

1 Answer 1


A simple voltage tester would work fine, you can test line to line and get 240v or line to ground to get 120v. Lack of voltage drop would only matter if you tested line to load when load is open. Even a non-contact sensor should work fine for determining voltage being present. You could also turn off all two-pole breakers.

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    It should be a double pole breaker , or a handle tied pair of breakers, I would check line to line then verify each line to ground. Especially if handle tied, I had a federal pacific panel not disconnect one leg , shocking surprise pun intended.+
    – Ed Beal
    Nov 13, 2019 at 22:03

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