DIYbanter - View Single Post

wrote:
IMO, the AC powered units are the best, so that you don't have to deal
with changing batteries. There is a very small chance that the power
could go off as part of a fire before the smoke detectors are
activated, but I think this is very remote. On the other hand, people
die every year in homes with smoke detectors where the batteries were
dead.

It's estimated that something like 50% of all battery smoke detectors
don't work because their batteries are dead/removed.

In the UK, mains powered interlinked smoke detectors are required by
Building Regulations, and if they're run off the lighting circuit they
have to have battery/capacitor backup as well.

Owain