"Jim Beaver" wrote in message
. net...

I've got hard-wired smoke alarms in my house, installed by my building
contractor when the house was built four years ago. . . .
And can anyone suggest why changing the
batteries in the alarm in the beige-ish photos doesn't stop the beeping?

Most smoke alarms contain tiny amounts of
radioactive elements that sooner or later stop
functioning as designed -- which may cause the
beep signal, to prompt you to replace the unit.

A single mains-connected smoke alarm in our
house died about seven years after installation.
We replaced it by a battery-powered unit since
power outages were then common where we live.

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)