Home built in 2005. These are interconnected Fireex smoke detectors (I believe because they have a yellow wire connected to the red wire). All the breakers are marked, but I don't see one for the smoke alarms.

Now I was away on business and my wife had an alarm chirping and couldn't get it to stop so she literally in wired it while it was hot! Could have killed herself.

Problem is I want to rewire it and I don't know how to cut the power to it since there is no breaker.

Thoughts?

In my state the smoke alarms cannot be on their own circuit breaker. They must be connected to a receptacle or lighting circuit. This is so people do not shut off the smoke alarms due to false alarms and have no protection as a result. In my state the smoke alarms are also required to have a battery backup in case the power goes out or the circuit breaker trips.

Using a non-contact voltage tester (This is what I use: http://tinyurl.com/FlukeTester ) you can safely test the circuit by flipping the circuit breakers off one at a time. If the smoke alarms are interconnected they will only be on one circuit. Smoke alarms are generally rated for 10 years of service, so yours should be replaced. I suggest that you also buy some better batteries as the ones that come with the new alarms are not long lasting. Home Depot sells long life lithium batteries that may last as long as the smoke alarm depending on use.

John Grabowski
https://www.MrElectrician.TV