In a domestic situation one has to have a smoke/fire alarm but does the legislation stipulate that it has to be hard wired to a MCB on the non-RCD side or could that be a simple battery operated (Wicks or B&Q) smoke alarm?

When you find a property without one and the landlord isn't keen on spending for hard-wired ones, would the battery operated ones satisfy the legislation?



Any feedback is much appreciated.
 
If memory serves me well, they should be on their own circuit ideally but they can be powered from an adjacent lighting circuit ie take a permanant live and neutral from a nearby light fitting
 
For rental properties isn't there guidance that says they must be mains powered. As for seperate circuits I thought that it was better, these days, to put them on a lighting circuit!!
 
Either way, if there's a smoke and a heat detector or two smokes they have to be interlinked so there's going to be some upheaval wiring the link if nothing else
 
I was also taught to put them on a frequently used circuit, such as lighting, so it would be obvious if a breaker had tripped and they were not working.
 
Hi Goody, Building Regulations, Part B, Fire Safety, applies to all new and refurbished dwelling houses. OSG 7.5.2 gives basic guidance and EGBR 10.2 and Appendix C gives a fuller explanation of the requirements.
 
Well just to add my 2penneth....."safety curcuits should nod be on an RCD"....but....all final circuits for use by either unskilled and/or uninstructed persons to be given additional protection by means of RCD ..etc...etc..
Mad innit.
Pull a feed of a lighting curcuit for your smokes and/or heats and i would say you satisfy both....(assuming the lighting circuit is upto the 17th of course)............
 
Hi GOODY
Can be on own dedicated circuit but its preferable to feed from a regular used lighting circuit as if the lights go off they will more likely notice and turn it back on whereas with a rcbo for smokes they are less likely to spot its off

they should be mains powered with battery back up and interlinked and placed in circulation areas between habitable rooms ie between kitchen and living room
there should be at least 1 per floor, thnink this is for floor area of upto 200m sq
at least 300mm from a light 300mm from walls not over openings in stairwells and preferably have a means of isolation without isolating the lighting circuit if fed from 1 but i believe by removing the smoke this classes as acceptible and no more than 7.5m from all habitable rooms
if the loft is habitable or going to be then you will also have to install one in there
if the kitchen isnt seperated with a door then a heat alarm needs installing

Electricians guide to building regs and OSG has this info mate
 
Gets me nowhere!

Apologies but I thought it pretty clear in the Kidde document so a couple of things here. Your OP mentioned the word legislation. Legislation is law / mandatory. What we are looking at here is various BS's like our 7671, not law as such but something which "can be used as a defense in law". Basically woe betide anyone who ignores these BS's. Same goes for fire alarms (BS5839 I think). The BS is basically the "prosecution's" go to guide in the event of us having done something outside these guides.

Grade D is the minimum as someone else has said and this is interlinked mains smoke and heat with battery backup. Now dive into your On Site Guide (p65, 7.5.2 Smoke and heat alarms (Part B).

The detectors and alarms are required to be:

a - be linked so that operation of one will initiate all units (mains powered smoke detectors may be interlinked by radio)
b - be permanently wired with an independent circuit from the distribution board (consumer unit) or supplied from a local, regularly used lighting circuit (there should be a means of isolating the supply to the alarms without affecting the lighting)
c - have a standby power supply such as a battery or a capacitor

So a+b+c = Grade D!

Of course if its a TT feed then you could consider feeding from an RCBO maybe i.e a high integrity circuit. Some even suggest say the stairs / landing lights on their own MCB / RCBO along with the smoke circuit. That idea comes from the outside chance that someone could go up to bed without having turned on any downstairs light and get into bed without having turned on any upstairs light (they used the bedside lamp). BUT they are more likely to switch the landing lights on at some time. If the breaker feeding the smokes is on the downstairs or upstairs circuit & has tripped they would never know. Very remote IMO and then of course you should still have the battery backup.

Gets deep doesn't it?
 
Last edited:
Sorry mate, forgot to add that these OSG "rules" come from Part B of the Building Regs for "new and refurbished dwellings" Could argue the flat is neither? Of course who is then responsible for changing the batteries in the smoke alarms?
 
was wondering, if you refurbishing only the kitchen, is it allowed main power your heat alarm but not link with the over smoke alarms which all ready exist in a house?because linking them means you have to rip the carpet ant floorboards and cut some holes in the ceilings which client is not happy with?or it has to be linked anyway?
 
Its the old damned if you do damned if you scenario, upset the customer or go against recommendations. The OSG says exactly this "Part B of the Building Regulations and the Building Standards Scotland requires all new and refurbished dwellings to be provided with a fire detection and alalm system" What the position is then on just refurbishing the kitchen I don't know. I'd strongly suggest interlinking with the old system and imagine anyone you asked like an insurer or Building Control would say the same. Appreciate the comments about ripping up floors etc. How about suggesting to them as a happy medium that now would be a good time to upgrade the whole smoke and fire system and go radio linked which is permitted. And a lot cheaper than tearing up floors! Maybe a letter with a separate quote to give yourself a bit of coverage. You could phone Building Control on the QT and include their comments in the quote/letter. "Steer" the customer so to speak.

I assume (not sure) that if the existing alarms are interlinked with 3-core and earth then if replacing with mains powered radio alarms in the same position you would disconnect the signal wire? Anyone?
 
Bump..

I've been looking at this one today also and still can't quite get it.

My customer has plans under BC which has porch extension, new kitchen & re-fabbed downstairs bathroom. Plans say "smoke alarm" (just the one) - with a location shown in downstairs hall.
New Approved doc B (fire safety) says 1.8 "Where a new habitable room is provided..alarm system should be installed"

>> But if alterations are made without a new habitable room (ie this case):
A) Is it strictly required to follow those guidelines? (ie one on every floor).
B) Approved doc B : 1.12 "At least one alarm on every floor".
>>If I am installing one anyway (irrespective of a "new habitable room" requirement of Doc B), does this put me outside the requirement for every floor. ie I could install just the one detector (rather than on every floor)?

(ie My customers plans are signed off by BC with just the one detector) Should I be putting in two anyway to avoid problems at BC completion?

Approved doc B 1.19 says it can be from a lighting cct. OK.. but.
>> But then Doc B and other guidance also says it should have independent means of isolating the power. Does this mean it could have a lighting switch so Mrs Smith can just turn it off? - Seems a bit dim to me. Do people really put in an on/off switch?
 

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