Bathroom RCD protection

[Jm1980]

Looking at a bathroom modification and wouldn't mind some input on the need for RCD protection.

Bathroom has existing light and wall fan. Customer wants downlights fitting and ive also said the fan needs an isolator as it currently doesn't have one. No other electrical circuits in the room. No supplementary bonding is present either and as the room is nearly finished, adding any is difficult.

Firstly, all work is outside the zones so my understanding is that part P doesn't apply?

The circuits obviously need RCD protection as per 18th and also as i have no supp bonding present. CU is a split load 16th edition style with upstairs and downstairs lights on the non protected side. The option to run a new bathroom dedicated circuit isn't feasible due to difficulty of run and customer not wanting this. As i see it then that leaves a couple of options.

1, switch the upstairs lights onto the RCD side at the CU thus protecting the entire circuit and thus the bathroom. This seems a good option although I'm risking any faults already present giving me RCD issues (borrowed neutrals and the like).

2, An easier option seems to be to run the lighting circuit into an RCD fused spur and then from this create my bathroom lighting and fan wiring. I see conflicting opinions on the RCD fused spur option though especially since upgrade to the 18th.

Any opinions appreciated.

 

[James]

The building regs DO apply, INCLUDING PART P

You intend to work in a special location
Also, the work involved is beyond that of a minor works certificate.

EDIT, @westward10 has pointed out this is incorrect.
Back to school james!

 

[Jm1980]

Hi James

I was under the impression that as the work is outside the zones that the work is not notifiable, that's the last NICEIC guidance i remember on it unless it has been changed?

 

[westward10]

Off the top of my head according to Part P it is only notifiable if the works are carried out within the boundaries of the zones, Part P only deem these areas as a special location. Outside of these it does not apply.
What make is the consumer unit.

 

[Jm1980]

Thats how i understand it westward, the CU is contactum

 

[SJD]

I think you are confusing two separate things. Building regs apply "everywhere", but you are only required to notify work "in the zones". For example, you still need to keep cables in safe zones, cut holes in joists in the correct places etc.

 

[Jm1980]

Agreed SJD, my query was regarding being notifiable. Ofcourse building regs will be adhered to, cable zones and routing methods will be correct.

 

[westward10]

Don't know the age of your consumer unit but if it is the Defender range you can get an rcbo.

https://www.electricaldirect.co.uk/product/contactum-6a-30ma-6ka-single-pole-rcbo-type-c-485638?vat=1&shopping=true&gclid=Cj0KCQiA1KiBBhCcARIsAPWqoSqbHY2M6XJQBKk40VpRxB4bHj1tioRbLaDzROHMucDiAjGI-fFN7nYaAr3ZEALw_wcB

 

[pc1966]

That place also seems to sell the B-curve, slightly cheaper:

https://www.electricaldirect.co.uk/product/contactum-6a-30ma-6ka-single-pole-rcbo-type-b-563968

 

[Spoon]

If changing to a RCBO, as you have already mentioned, you may have problems with borrowed neutrals on a light. Most prob the landing light. (I would have the same in my house) If the customer doesn't want his walls messing to rewire switches then you could always change the light to be controlled by a wireless switch, like Quinetec.

 

[Jm1980]

Cheers, definitely an option but moving the mcb onto the rcd side probably easier (space in CU) although id lose a bit of installation division. My main worry is inheriting faults on other parts of the circuit if i rcd the lot.....

Any thoughts on using the rcd fcu option?

 

[westward10]

Strictly speaking you would have to note an rcd spur as a departure from BS7671 as they are not currently listed as a device for providing additional protection.

 

[Spoon]

Any thoughts on using the rcd fcu option?

As @westward10 has already mentioned, these are not currently listed in BS7671.
There was a thread somewhere saying that they may be adding it but it hasn't happened.

Strange that these are still being manufactured, if they are not to current regs though, or is it ok just to put them down as a 'departure from BS7671'?

 

[westward10]

There is nothing wrong with noting a departure provided you can prove the departure leaves the installation no less safe than as required by BS7671.

 

[Jm1980]

On a wider point isnt this poor by the reg writers?

Not got my 17th to hand but were 7288 devices listed for additional protection in there? Presumably so.

The need for rcd’s on bathroom circuits must throw this conundrum up often so you would think this would be clarified with reasoning one way or the other by those that write the regulations.