OK so not DIY but some here do find such info interesting.

I am doing an EICR on a block of 38 rented flats all owned by the same
company. One and two bed flats with just a single mains powered smoke in
the hallway (as per regs when they were built in 1994)

Out of the 16 I have tested 8 of them have either had the MCB to the
smokes turned off and the battery removed, the mains disconnected at the
smoke and the battery removed or the smoke heads have been removed.


I accept that the tenants have probably done some of this DIY themselves
to save buying a new battery.

However the most disturbing one is a flat that a tenant moved into 4
weeks ago. The mains had been disconnected from the smoke, taped up and
shoved into the ceiling as well as the battery having been removed.
Almost certainly like that when she moved in 4 weeks ago.

--
Adam