On Sunday, January 31, 2021 at 9:17:06 PM UTC-5, wrote:
On Sun, 31 Jan 2021 17:15:02 +0000, Mattinstafford
wrote:

I've tried every circuit breaker in the house except.for the master and the smoke detector has remained hot. I suspect that my smoke detectors are wired together but supplied by two different circuits so that they will go off together. I'm simply going to cut power to the whole house to change the hard wired units rather than try to solve a very complicated puzzle.
Hot like 120v present or just functioning? They usually have battery
backup. If they really are being fed from 2 circuits, fix that first
or you might be needing those smoke alarms.

If they really are supplied by two circuits, it would be easy to prove it. Just turn off
all breakers and the smoke detectors would lose power. Then turn them on one at
a time until finding one breaker where they have power again. Turn that breaker off
and proceed to try all the remaining breakers. Also IDK why he didn't just open the
main breaker, that would have proven whether they are battery backed up and that
was what was going on.