RCD Required?

[OxiaUK]

I have a new garage and had previously run cable to it ready for it to be connected later. I ran a 6mm T+E cable from the consumer unit (cant get armoured all the way to it) it then terminates in a wiska box on the wall outside and continues in 6mm 3 core armoured. I had planned to have no RCD at the house end and the garage protection at the garage end....

the electrician has now come and said the cable at the house end needs to be RCD protected due to it been T+E

The T+E runs in to the ceiling and is clipped to the joists along its run with fire clips every so often.

Is it a definite no no to not have the RCD? it seems like I would have tripping in the house if a fault happens garage side.

Thanks

 

[EFLImpudence]

The T&E does not require an RCD just for being T&E.

However, (fundamentally) if it is concealed <50mm below a surface in any part of its run, then it must be RCD 'protected' or protected by earthed metal by various means similar to the way the armoured cable is.

You are right about not wanting tripping in the house by faults in the garage.
That's why armoured is used.

 

[OxiaUK]

The T&E does not require an RCD just for being T&E.

However, (fundamentally) if it is concealed <50mm below a surface in any part of its run, then it must be RCD 'protected' or protected by earthed metal by various means similar to the way the armoured cable is.

You are right about not wanting tripping in the house by faults in the garage.
That's why armoured is used.

Thanks for your reply, is the 50mm rule still the same if this is under floor boards like all other cables? I have lighting cables etc that run under the floor that are not protected via RCD

 

[EFLImpudence]

Thanks for your reply, is the 50mm rule still the same if this is under floor boards like all other cables? I have lighting cables etc that run under the floor that are not protected via RCD

Well, doesn't really apply - but sort of.

Loose under the floor would be >50mm from surface anyway and if clipped to joist would not be done <50mm.

 

[JohnW2]

The T+E runs in to the ceiling and is clipped to the joists along its run with fire clips every so often. Is it a definite no no to not have the RCD?

However, (fundamentally) if it is concealed <50mm below a surface in any part of its run, then it must be RCD 'protected' or protected by earthed metal by various means similar to the way the armoured cable is.

Loose under the floor would be >50mm from surface anyway and if clipped to joist would not be done <50mm.

I'm a bit confused. I thought that, regs-wise, the "<50mm rule" (and, indeed, the concept of 'safe' zones) only exists in relation to cables concealed in walls or partitions, rather than "below a (any) surface", and hence doesn't apply to cables above ceilings and/or below floors. Is that not correct?

Kind Regards, John

 

[EFLImpudence]

Yes, that is correct in as much as the regulation for cables concealed in walls only applies to walls.
That is why I was a bit cagy.

However, the regulation 522.6.201 for cables under floors, while not mentioning RCDs, does state the 50mm minimum (as this is easy to do compared with walls) OR compliance with 522.6.204 - the earthed metallic coverings.

Therefore whilst cables under floors do not have to have RCD protection, they must be installed in the same method as cables in walls that do not require RCD protection, so the RCD question does not arise.


Edit - Used BYB, presume everything is still the same.

 

[JohnW2]

Yes, that is correct in as much as the regulation for cables concealed in walls only applies to walls. ... However, the regulation 522.6.201 for cables under floors, while not mentioning RCDs, does state the 50mm minimum (as this is easy to do compared with walls) OR compliance with 522.6.204 - the earthed metallic coverings. ... Therefore whilst cables under floors do not have to have RCD protection, they must be installed in the same method as cables in walls that do not require RCD protection, so the RCD question does not arise. Edit - Used BYB, presume everything is still the same.

I haven't looked back at the BYB but, in BS7671:2018, the 50mm minimum appears only to relate to where a cable passes through floor/ceiling joists etc. - so would not apply to, for example, a cable running alongside the length of a joist (without passing through the joist). However, the reg dopes start with a 'catch all' ...

... A cable installed under a floor or above a ceiling shall be run in such a position that it is not liable to be damaged by contact with the floor or ceiling or their fixings ...

...which can presumably interpreted in whatever manner one feels appropriate.

Kind Regards, John

 

[ericmark]

Many consumer units will allow the use of a RCBO which is a RCD and MCB combined, back in 2008 the rules changed so was 522.6.5/6/7 but it is not retrospective, so if designed before 30st June 2008 then it does not need the RCD protection, it is design date not installation date or testing date.

 

[JohnW2]

...back in 2008 the rules changed so was 522.6.5/6/7 but it is not retrospective, so if designed before 30st June 2008 then it does not need the RCD protection, it is design date not installation date or testing date.

It did not need RCD protection when installed.

However, someone undertaking an EICR today will assess things in relation to what the current (now) regulations would require, and if something does not conform with the current regs, they then have to decide whether that non-conformity constitutes a non-compliance (i.e. whether, in their judgement, it makes the installation 'potentially dangerous').

Kind Regards, John

 

[ericmark]

We have talked about this before, an EICR no longer relates to BS 7671 code 4 was removed. The fails are FI, C1 and C2 and if not considered potential dangerous in 1950's then it can hardly be classed as potential dangerous today.

There are things which we did not have in 1950's which we do have today, and it did take a little time for regulations to catch up with new practices, metal lamps and switches for example, so there have been changes which were slow catching up.

But it does not say any more would not comply with current regulations if designed today code 4. And some thing designed in 2007 can still be installed to BS7671:2008.

As to if given a design signed by the designer in 2007 anyone would sign for installation, inspection and testing today is unlikely, but in 2009 very likely.

But if the paperwork for the design is presented to the installer he could in theroy install in non domestic or when being inspected by the LABC, however for a scheme member there is no provision to use three signature forms, so in real terms it will not happen.

 

[JohnW2]

We have talked about this before, an EICR no longer relates to BS 7671 code 4 was removed.

WE know that is your view but, not only does it not really correspond with (at least my idea of) common sense, nor the way in which the vast number of people view the situation when undertaking EICRs, but nor is ut what BS7671 says, namely ....

... (vi) the identification of installation defects and non-compliances with the requirements of the relevant parts of
BS 7671, that may give rise to danger.

... although iut does qualify that with ...

... NOTE 2: Existing installations may have been designed and installed to conform to previous editions of BS 7671, applicable at
the time of their design and erection. This does not necessarily mean that they are unsafe.

"Not necessarily unsafe" obviously impliues "possibl unsafe" - so, as we discuss so often, it is down to the judgement of the inspector.

... if not considered potential dangerous in 1950's then it can hardly be classed as potential dangerous today.

It's a pity that you said 1950s, rather than 1940s - since I could otherwise have cited smoking, which is now classed as far more than "potentially dangerous". However, there are may things which were not considered to be potentially dangerous in the 1950s (or later) which would definitely be considered to be dangerous today. For example, as I've said before, as a young child in the 50s, I was allowed to 'play with' X-reay machines in she shops. More in context, in that era I was living with light switches with covers which I could (and sometimes did!) unscrew 'without the use of a tool'

Kind Regards, John

 

[OxiaUK]

thanks for everyone's replies... so what is the best thing to do then if like in my case there is no physical way to get the armoured cable all the way to the consumer unit? I can only get it to within 1m then it would have to be T+E

 

[BS3036]

Is the twin and earth buried? I think EFLI went over this already. Also I wonder why the SWA cannot reach the CU. Is that because it got cut off too short?

 

[OxiaUK]

Is the twin and earth buried? I think EFLI went over this already. Also I wonder why the SWA cannot reach the CU. Is that because it got cut off too short?

The twin and earth would be under the upstairs floor for 1m before it reaches the outside wall. We live in a cottage and the routes are impossible to fit a 6mm armoured cable. I would not be able to bend it round corners etc

 

[BS3036]

The regulations refer to a cable 'concealed in a wall or partition'. They don't mention floors or ceilings. I have always taken such cables to be exempt from the need for an RCD.