On 18/03/2018 23:46, Bob Eager wrote:
On Sun, 18 Mar 2018 23:20:40 +0000, ss wrote:

On 18/03/2018 21:24, alan_m wrote:
In addition, there will be a 10-year age limit for alarms and all
alarms will have to be ceiling-mounted, and should be
interlinked.".........

As they have to be interlinked do they also have to be mains powered?

I dont know, I am only asking as I am writing to my MP asking how he
expects those that can ill afford to pay for the installation.

The age limit is reasonable, as that is usually the working life of the
detector.

Well it is *certainly* not the effective lifetime of the source: Am 241
has a half life of 432 years. So after 10 years the strength is only
down by about 2%.

As an aside, a Stanford web site says the annual dose from smoke
detectors is between 0.1 and 0.5 bananas per year.

http://large.stanford.edu/courses/2011/ph241/eason1/