In article ,
Van Chocstraw wrote:

Kurt Ullman wrote:
I have some 20 y/o hard-wired smoke detectors that I want to replace
with newer hard-wired ones. How do I figure out which circuit breaker to
trip or is this an issue with smoke detectors?


If it's not marked in the box you'll have to trace the circuit either
electronically or manually.

Or just short the two leads. That's an efficient way to identify the
correct breaker.