I have three smoke alarms in my house, all hard wired into my electric system. I thought I was set. Never had to worry so long as I could look up and see that comforting green light saying they were working.
Well, it turns out that smoke alarms have a life span of about ten years before their efficiency starts a pretty steep downward spiral. Who knew?
I know now because a very nice friend who is also a rabid fireman came over, checked them all, pulled them off the walls, bought me three new ones, and installed them, all in less that two hours. And now my birds and dogs and I are very, very safe again.
So I’m passing this knowledge on for what it’s worth…and it might be worth your life.