On 29 Aug, 20:26, Martin Pentreath
wrote:

I don't think mains is essential, but they must be the ones with non-
removable batteries (so the arsey tenant can't disable them while he
burns his toast of a morning). I refer the honourable gentleman to the
answer given some time ago by Mr Lurch:

"BS5839: Pt 6. Basically it says that as a minimum in dwellings you
require a smoke detector in each communal area, so in a average 3\4
bed semi\detached you'd have one in the hall and one on the landing.
These detectors should have built in non removable backup, lithium
battery\capacitor or similar."

http://groups.google.co.uk/group/uk....2c0f847?hl=en&

Correction - some further research into BS5839 suggests that battery-
powered ones are OK only in bungalows and flats (if they are rented).
Quite what the number of storeys has to do with it is not clear to
me.

"BS 5839: Pt.6 acknowledges the advantages of the single, battery
operated smoke alarm. They are simple to install and offer protection
at very low cost. Battery operated smoke alarms conforming to BS 5446:
Pt.1 are recommended. Battery operated smoke alarms are suitable for
owner-occupied buildings with up to two storeys, as well as for rented
bungalows and flats. However, battery operated smoke/heat alarms do
have drawbacks. Occupants on a tight budget may not be able to afford
to replace the batteries. A significant number of tenants have also
been shown to remove the batteries to prevent false alarms or to use
in other battery powered devices and then forget to replace them. For
this reason, the Code recommends that these alarms should not be used
to protect tenants in properties of more than one storey - and even
then the batteries should be sealed-in and have a life in excess of 5
years.

As an aside, landlords have now been found liable in cases where
tenants themselves have disabled an alarm. For this reason, it is
unlikely that landlords will be able to trust tenants to adequately
look after the alarms. The Code highlights the fact that battery
powered alarms are only suitable for owner-occupied properties if the
likelihood is, that batteries will be replaced within five days of a
low battery signal."

http://www.safelincs.co.uk/page.php?xPage=bs5839-6.html

None of this has the status of statute and it doesn't seem to be
enforceable before a fire - it just looks like compliance with the BS
provides the landlord with a good defence to any civil or criminal
case after the event.