Simple job?

[Jase_82]

Scenario: "I'd like a single smoke alarm hard wired in my house so I don't have to worry about changing the batteries if I decide to rent it out in the future" says the customer.

right, smoke alarm in hallway off of upstairs lighting circuit, 0.5m away from ceiling rose. So far so good. Check CU... 2 b6 mcb s for upstairs and downstairs lighting, not protected by rcd. Ahhh. Will require an RCBO as well. And it's notifiable works. check lighting circuits... Looks like there's a borrowed neutral...

So the options I see are: surface trunk the new smoke across the ceiling (won't be an option for most customers) so no rcbo needed; or run an earthed metallic sheathed cable (is there a cable that's practical for this?);or put both living circuits onto one rcbo if loading is appropriate and wire smoke normally; or start ripping the house apart feeding new cables for the lights and putting in new RCBOs for lighting circuits.

A quick cheap job turned into an expensive one, or am I missing a simpler way to do this?

 

[KAS1]

Why the RCBO?

 

[MDJ]

Smoke detector, rcbo? really? didn't know that.

- - - Updated - - -

Why the RCBO?

HUH beat me too it again lol

 

[Jase_82]

Because its running new cable from an existing circuit which will not be more than 50 mm deep

 

[Octopus]

Notifiable - don't think so.

 

[Richard Burns]

In a wall?

 

[Jase_82]

No, above a plasterboard ceiling.

 

[MDJ]

whats the problem then?

 

[kingeri]

Thought you were coming off lighting circuit and putting smoke next to light - you won't need to add RCD protection ????

 

[Jase_82]

So the new cable wouldn't need protection by an rcd?

 

[Richard Burns]

So no RCD protection is required, no notification to building control is required.
The borrowed neutral should be sorted but is not part of your remit, but probably good practice.
Run 0.5m of cable from light fitting to smoke alarm, test your part of the circuit, recommend residual works, done.

 

[kingeri]

So the new cable wouldn't need protection by an rcd?

Not as far as I can see,why do you think it would?

 

[jaydee81]

no rcd required 50mm rule only applies to wall or partition not notifable works either as your are just adding to an existing circuit

 

[Jase_82]

Thanks, I just assumed that the 50mm rule applied to ceilings as well, but thanks for clearing that up.

 

[Rockingit]

If you think about it, running the new cable will involve going UP - into the loft (if I've read the OP right) - where it effectively becomes a surface run.

And generally speaking there's no need to provide RCD protection to smokes and alarm panels (in fact there are some distinct disadvantages), so long as the cables have been run correctly - and as the outlets are normally to be found on ceilings........

 

[KAS1]

Is it a concrete ceiling ?

Thanks, I just assumed that the 50mm rule applied to ceilings as well, but thanks for clearing that up.

 

[DNS1]

522.6.7

I just had to look it up myself to see the exact wording. It refers to "walls and partitions" only

 

[saveloy]

Why not tell the tight arse skinflint wannabe amateur landlord to do a proper job and fit a proper interlinked system with a couple of smokes and a heat alarm. Then at least if he does embark on his tinpot landlord business, his prospective tenants will be properly protected, and in the meantime he will as well.

 

[JoeDurky]

Going to sound really stupid but currently sub contracting to council on/off and any circuit worked on/ new circuit even if surfaced mounted in trunking has to have rcd protection or would this just be there guidelines. Don't question it as fitting an rcbo is an extra £12.50 n mains change £25 megga bucks

 

[saveloy]

That is councils own spec.