Rcd spur for Bathroom electrics

[Thrashman]

Hi Everyone ,
I hope everyone is having an awesome week,

I know this question has probably been covered before on previous posts, but wanted to get everybody else’s opinion and take on it.

So I’m quoting on a job and it entails replacement of existing central light in the bathroom for five times new LED spotlights, a new LED mirror and New ceiling mounted extractor fan with fan iso switch .

The existing fuse board is an old Wylex re-wireable, So currently no RCD protection.
I have talked to the customer about the benefits of upgrading the existing fuse board to a new consumer unit but of course they don’t currently want to spend the money even though they are considering upgrading it in the future on my advice.

So to provide RCD protection for the new work and 3amp ocpd for the fan I am considering the option of relocating the mains feed to the bathroom through an RCD spur with 3 amp fuse located on the exterior of the bathroom And from there to all my alterations as listed above.

Had considered putting the RCD spa at the origin of the installation but as I have yet to survey, this could cause havoc with Borrowed neutrals etc, Oh my option above seems the most plausible and best way to move forward to comply.

what do you all think , any better options ??

thanks in advance

?

 

[pc1966]

If you can check for borrowed neutrals and it is OK then you could just use a surface box and RCD spur at the origin (CU end). Makes it easier for later replacement and it is in the obvious place to look if lights, etc, go out. Also benefit of safer operations for all of the lights & related cables.

Otherwise putting it immediately outside the bathroom also sounds quite reasonable. Even inside, if it is safely away from water zones and out of obvious touching range for children, etc. Might already be a fan isolator that could be made double-width box.

I'm sure there will be others with better ideas!

 

[Mike Johnson]

Is the ceiling above 2.4M and do you mean down lights rather than spotlights?

 

[pc1966]

If you have a leakage clamp meter and cables are accessible you should be able to clamp the T&E supplying the bathroom at the CU and try any double-switches to see if there is a borrowed neutral.

Won't pick up actual earth leakage though due to E also being in the clamp, but that is not what is needed here.

 

[Thrashman]

Is the ceiling above 2.4M and do you mean down lights rather than spotlights?

yes I mean down lights, Can’t currently confirm ceiling height as of yet to survey of the job. Remote survey with pictures from customer as we are currently in this lockdown. ?

 

[westward10]

At present you will have to note on any Certification that an rcd spur is a departure from BS7671 for use as additional protection.

 

[radiohead]

At present you will have to note on any Certification that an rcd spur is a departure from BS7671 for use as additional protection.

For the benefit of the OP this is because the 18th omitted to list the Bs number of devices like RCD FCU's and RCD socket outlets under the Bs numbers of RCD's which can provide additional protection. They have since clarified that this is an error which will be rectified in the amendment.
As above under the current Bs7671 an RCD FCU used for additional protection technically does not comply, and would be a departure to be recorded on the cert.
You are unlikely to be shot if you neglect to do so though.

 

[Thrashman]

For the benefit of the OP this is because the 18th omitted to list the Bs number of devices like RCD FCU's and RCD socket outlets under the Bs numbers of RCD's which can provide additional protection. They have since clarified that this is an error which will be rectified in the amendment.
As above under the current Bs7671 an RCD FCU used for additional protection technically does not comply, and would be a departure to be recorded on the cert.
You are unlikely to be shot if you neglect to do so though.

Thanks for the clarification on that, And the same as you’ve noted that this will be rectified in the first amendment to the 18th. Thanks , Otherwise any alteration on any installation without RCD protection would require a new consumer unit.
Thanks for the clarification

??

 

[Midwest]

I've read similar threads on this subject, and when I was doing such work (A3 17th), used to install an RCD FCU local to the bathroom.

Now if I recall, some members argued under the 18th, an RCD had to be at the origin of the circuit, even on any alteration or addition?

 

[Risteard]

Thanks for the clarification on that, And the same as you’ve noted that this will be rectified in the first amendment to the 18th. Thanks , Otherwise any alteration on any installation without RCD protection would require a new consumer unit.
Thanks for the clarification

??

Amendment 1 was issued in February and solely deals with Section 722 (EVSE Installations). So there has been no change.

I'm not convinced that a future Amendment will address it either, given that British Standard 7288 explicitly states that these devices cannot provide additional protection.

 

[Midwest]

So if the RCD FCU or Socket Outlet complies with BS 7288:2016,
it’s complies with BS7671 18th edition?

 

[pc1966]

I'm not convinced that a future Amendment will address it either, given that British Standard 7288 explicitly states that these devices cannot provide additional protection.

I don't have a copy of this (and won't be paying for it to argue here!) but what does it actually say? One of the IET threads discussing this omission has something about it specifying:

SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD

But that is not very helpful. After all if the feed is RCD protected what is the point of the SRCD? It would provide no selectivity against a 30mA RCD upstream, and a 100mA S-type (for TT incomer, etc) is not providing adequate shock protection.

Or do they simply point out the SRCD device is not protecting the feed cable so it would need to be, say, Flexishield style to provide "additional protection" anyone from nailing it?

Being practical if all the choice the customer can currently afford is the existing rewirable fuse and having an SRCD in addition, then it is clearly better than their existing no-RCD setup. In past editions it would have met the RCD specification by performance, where as now in the 18th the RCD specifications are given as limited set of standards that don't include BS7288 for reason(s) unknown.

 

[westward10]

There is no guarantee that any future amendments will include these devices as satisfying additional protection. In my opinion to ensure compliance with BS7671 as opposed to entering a departure I would not fit them and if that means a consumer unit change then so be it. Departures as we know have to ensure safety outside the scope of BS7671 is not compromised and never having had much faith in rcd sockets and spurs I would not be using them to fulfil a departure.

 

[pc1966]

I guess another route short of a full CU change would be to fit a "garage CU" next to the main board to house a conventional RCD to feed the lighting circuit (also fitting a MCB replacment for the fuse to make it easy to reset instead of the home owner having to faff about with fuse wire).

Yes, the OP will still need to check for borrowed neutrals, but having all that light circuit on RCD is much better anyway.
[automerge]1588496986[/automerge]
Looking at the BEMA guide to RCDs here:

The RCD Handbook - Guide to The Selection and Application of Residual Current Devices (RCDs)

www.beama.org.uk

It has in Table 3 (page 22) the various use cases, and for SRCD and FCURCD both are N for protecting fixed wiring.

 

[Midwest]

I’ve read on the net (@Ian1981) #24.

RCD fused spur suitable or not?

Good Evening All, I have been asked by the family of some elderly neighbours to install a socket in an understairs cupboard for a small chest freezer and add a lighting point in the same cupboard. Installation is protected by a Wylex 3036 rewireable board so had no rcd protection and the...

www.electriciansforums.net

 

[radiohead]

There is no guarantee that any future amendments will include these devices as satisfying additional protection. In my opinion to ensure compliance with BS7671 as opposed to entering a departure I would not fit them and if that means a consumer unit change then so be it. Departures as we know have to ensure safety outside the scope of BS7671 is not compromised and never having had much faith in rcd sockets and spurs I would not be using them to fulfil a departure.

I read somewhere that the IET had admitted the omission was an error which would be rectified. Personally I would have no concern at all with using an RCD FCU if it was appropriate for an instance of additional protection needing to be installed for a minor alteration to an existing circuit.

 

[westward10]

How would you confirm it provides additional protection as required by BS7671.

 

[radiohead]

How would you confirm it provides additional protection as required by BS7671.

I wouldn't, in fact I doubt I'd even note it as a departure. I'd record on the MW cert under the description of work carried out that an RCD FCU has been installed as a means of additional protection, and have no doubt at all that the RCD FCU will do exactly that. There is not a snowballs chance in hell that if a case went to court anyone would be prosecuted for installing a device with the correct tripping current, which tripped in the required time (measured and recorded) and was manufactured by a reputable manufacturer.
Some things are just not worth getting overly particular about.

 

[westward10]

Nevertheless it is a departure no matter how you dress it but if that is your manner of things fine by me.

 

[Ian1981]

How would you confirm it provides additional protection as required by BS7671.

Consult manufacturers instructions and if need be reference bs7288 and make sure that at 5x the rating of the rcd socket/spur, it disconnects within 40mS.
Other than that I’m not sure how you would go about proving that the degree of safety is no less than full compliance with bs7671.