Nothing was disconnected - i just did not resign up when I bought the house. If i shut off the main breaker to the ouse, can I be sure the smoke alarm wires are dead - no electricity in them?

  • Nope! I did the same thing when removing popcorn from my ceiling. Turned off all the breakers assuming I was good, and still almost got shocked by my smoke alarms. – Doresoom Jan 13 '15 at 15:54

OK, clarify. Are you referring to alarm system detectors, or hard wired line-voltage (120V) smokes?

Either way, if you shut off the main, you should have no line voltage power anywhere. Line voltage smokes can, and typically do, have battery backup (9V battery), but this would NOT pose ANY safety hazard with regard to working on them.

If you are talking about an alarm system, then there is also mostly likely a system battery backup, but again, this should pose no safety hazard at all since these systems run on low voltage anyway.

  • 1
    +1 And always check wires with a non contact tester before handling them, no matter what breakers are turned off. – bib Jan 4 '15 at 23:38

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