I found a smoke detector in my house that appears to have two wires feeding it from two different circuits. Is this OK?

  • 1
    Have you traced both wires back to the service panel? It's more likely that you have one set of wires going to the service panel and one to another smoke detector. – Niall C. Nov 10 '14 at 22:26
  • yup traced both back to panel. Two circuits feeding one smoke detector. – Darrin Nov 10 '14 at 22:40
  • Two circuits, or two wires? It takes two wires to make one circuit, in most cases... – keshlam Nov 10 '14 at 22:41
  • Each wire traces back to a different breaker – Darrin Nov 10 '14 at 22:43
  • Are the breakers connected so when one trips the other turns off as well? If so that is totally normal (and by code). Each circuit has 2 wires; one live and one neutral. – ratchet freak Nov 10 '14 at 23:54

If your smoke detector was 240V, then you would have a hot from each leg of your service powering it from two breakers. There may or may not be a neutral, and there should be a ground. The two breakers would need to be on top of each other (most breaker panels alternate legs) and should be tied together so they can't be operated independently.

If the smoke detector is 120V then I doubt it's being fed from two circuits and might have made an error in tracing. The best way to know for sure is to measure the voltage with a multi-meter.

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