I appreciate it isn't an electrical issue so no code just an observation / recomendation

6. Type of alarms

The regulations do not stipulate the type of alarms (such as hard wired or battery powered) to be installed. Landlords should make an informed decision and choose the best alarms for their properties and tenants.

www.gov.uk/.../the-smoke-and-carbon-monoxide-alarm-england-regulations-2015-qa-booklet-for-the-private-rented-sector-landlords-and-tenants

So it depends on the Fire Risk Assessment, so for example will tenants hear an alarm on another floor on the escape route? 

Thank you.  That was how i read it on i think  was a smoke angel site.  I had it in my head they had to be mains.

Gary

Contact a supplier such as AICO for guidance. Last time I looked, wired smoke and heat alarms are only permissible in England, no battery types are allowed in rented properties and they must all signal an alarm to each other wirelessly. They don't fall under BS7671 apart from the mains connection. 

That was my understanding as well but thought I might be getting confused with new work.  The Government document in the link does not say that. It says batteries are acceptable although it is dated 2015. It says the same on another site i looked at as well which is why i questioned it. 

Gary

It's different in the 4 nations now of GB. You'll need to look at the relevant Building Regs in the country you're talking about.

I think it's got more confusing as technology changes - battery-only used to mean a PP3 that would go flat after a year and could be removed by tenants on a whim and mains only ones could be defeated by a power cut (or switching off an MCB). But now we have the option of mains + backup battery (or capacitor) or even battery ones that where the battery is good for the lifetime of the detector (10+ years) and sealed in so it can't be removed - so all the pros and cons can dance about a bit.

   - Andy.