RCD on bathroom circuit

[Mecca]

Here is the scenario.

EICR has been done on a flat.

The bathroom doesn't have its lighting circuit protected by RCD. Other circuits in the flat are RCD protected. There is supplementary bonding in place in the bathroom with good continuity between metal pipes and from metal pipes to earth. However, the main water and gas bonds are not in place as both supplies are plastic. Electrician has failed the report (C2) saying that RCD protection is required in the bathroom. Is this correct, even though main bonding isn't required in the first place? I mean, does supplementary bonding rely on main bonding being in place, even on a plastic supply? I don't want to have to pay for RCD protection and/or main bonding if it's not required.

Any advice appreciated

 

[EFLImpudence]

The bathroom doesn't have its lighting circuit protected by RCD. Other circuits in the flat are RCD protected. There is supplementary bonding in place in the bathroom with good continuity between metal pipes and from metal pipes to earth.

Ok.

However, the main water and gas bonds are not in place as both supplies are plastic.

It is not possible to bond plastic.

Electrician has failed the report (C2) saying that RCD protection is required in the bathroom.

I would say that should be C3 - improvement recommended rather than potentially dangerous - but then that is the trouble with EICRs.

Is this correct, even though main bonding isn't required in the first place?

It is nothing to do with main bonding.

I mean, does supplementary bonding rely on main bonding being in place, even on a plastic supply?

No. Nothing to do with it.

I don't want to have to pay for RCD protection and/or main bonding if it's not required.

Would it be that difficult to change the bathroom circuit to the RCD side?

 

[Murdochcat]

Rcbo for lighting circuit ?

 

[EFLImpudence]

I don't want to have to pay for ... main bonding if it's not required.

Just to emphasize it is not a matter of choice or something that can be altered.

You cannot "main bond" plastic pipes because plastic does not conduct electricity, therefore there is nothing to bond - i.e. join electrically.

 

[ericmark]

It changed in 2008 701.415.2 Supplementary equipotential bonding had "Where the location containing a bath or shower is in a building with a protective equipotential bonding system in accordance with Regulation 411.3.1.2, supplementary equipotential bonding may be omitted where all of the following conditions are met:
(i) All final circuits of the location comply with the requirements for automatic disconnection according to Regulation 411.3.2
(ii) All final circuits of the location have additional protection by means of an RCD in accordance with Regulation 701.411.3.3
(iii) All extraneous-conductive-parts of the location are effectively connected to the protective equipotential bonding according to Regulation 411.3.1.2.
NOTE: The effectiveness of the connection of extraneous-conductive-parts in the location to the main earthing terminal may be assessed. where necessary. by the application of Regulation 415.2.2."

But "BS 7671:2008 Requirements for Electrical Installations was issued on 1st January 2008 and is intended to come into effect on 1st July 2008. Installations designed after 30st June 2008 are to comply with BS 7671:2008."

There is something similar in each edition, so no requirement to upgrade. However the code 4 does not comply with current edition was dropped as being unhelpful so it is now down to the inspector as to how he codes it, and lets face it 230 VAC is always potentially dangerous so you can't say he is wrong.

The problem is how does one show a non existent fault is corrected? I can issue a minor works to show a RCBO has been fitted or a RCD FCU but can't issue anything to say a non existent fault is corrected, so rather than argue the toss, just fit a RCD FCU to lighting supply to bathroom, there is no requirement to be re-tested, just need the paperwork to show corrected. Anyone who can fit a RCD FCU can make out the minor works simple.

 

[Mecca]

Thanks for your help with this. I guess the crux of my query was whether supplementary bonding would be effective if there is no main bonding as this is what the electrician was implying. There is copper from the stopcock to the household pipes, but the supply is plastic. Likewise the gas is a plastic supply with copper after the meter. The cost of fitting an RCBO to the lighting circuit is not that relevant, it's more whether the C2 assessment is correct in the first place

 

[Murdochcat]

If it’s a rental property I would say you should fit the RCBO

Duty of care and all that

 

[JohnW2]

Thanks for your help with this. I guess the crux of my query was whether supplementary bonding would be effective if there is no main bonding as this is what the electrician was implying.

As has been said, supplementary and main bonding are totally different v things, with different purposes - so, yes, supplementary bonding (if required) would be effective (for its intended purpose) even if there was (and could be) no main bonding.

Supplementary bonding exists to ensure that all the touchable metal within a room are at the same electrical potential, so that an electric shock cannot result of two of them are touched simultaneously - i..e.it is something totally 'local' to the room. On the other hand, main bonding exists to avoid a situation in which metal pipes entering a building from underground (hence at true earth potential) cannot be at a different potential from the 'earthing system' of the electrical installation (hence touchable metal associated with the installation).

However, bonding is irrelevant to this discussion. For a long time there has been a requirement for any circuit 'serving a bathroom' (or even just 'passing through a bathroom') to be RCD protected, regardless of any considerations of supplementary bonding.

What may be confusing this issue is that having RCD protection (which, as above is 'compulsory' for everything in bathrooms anyway) is one one of the requirements for being able to omit supplementary bonding in a bathroom.

Kind Regards, John

 

[Mecca]

Thanks John. RCD not present wouldn't be a C2 though surely?

 

[Murdochcat]

Thanks John. RCD not present wouldn't be a C2 though surely?

Why won’t you just bite the bullet and get the rcbo fitted ?

Not expensive and if it’s a rental I would say you should do it

 

[JohnW2]

Thanks John. RCD not present wouldn't be a C2 though surely?

Unfortunately, given how EICRs work, that's entirely down to the opinion/judgement of the person undertaking the EICR.

I would imagine that a good few would be far more inclined to code absent RCD protection as C2 in a bathroom than anywhere else.

One could say that BS 7671 appears more concerned with the lack of RCD protection, particularly in bathrooms, than many of non-compliances with regs. Long before requirements for RCD protection, in general, were 'extended' (to now include virtually all sockets circuits, and also lighting circuits), there was (as I've said) a requirement for RCD protection of any circuit servicing, or passing through, a bathroom. Furthermore, absence of required RCD protection is the one and only non-compliance for which BS 7671 gives any guidance about EICR coding, saying the the absence of required RCD protection should be coded as "at least C3".

Kind Regards, John

 

[Mecca]

Unfortunately, given how EICRs work, that's entirely down to the opinion/judgement of the person undertaking the EICR.

I'm sure that's true and I'm not going to ask him to change his mind. What I really wanted to get to the bottom of is that he specifically said that the supplementary bonding counted for nothing as there was no main bonding, therefore an RCD would be required for the bathroom circuits. That is what I am disagreeing with. If he simply said that there needs to be an RCD on that circuit because it was otherwise unsafe then fine. Although I would disagree with that also

 

[Mecca]

Why won’t you just bite the bullet and get the rcbo fitted ?

Not expensive and if it’s a rental I would say you should do it

Well I probably will, but that doesn't really answer the question

 

[JohnW2]

I'm sure that's true and I'm not going to ask him to change his mind.

Fair enough - although, if it were me, I might, on principle, at least have a go at getting him to change his mind - since, as I said, the decision is 'at his discretion' (although, per what Murdo has written, I would, if it were rental property, probably want to add the RCD protection,anyway, even if the EICR coding did not require it).

What I really wanted to get to the bottom of is that he specifically said that the supplementary bonding counted for nothing as there was no main bonding, therefore an RCD would be required for the bathroom circuits.

As I said, that argument is nonsense. Supplementary bonding will do what it is there to do regardless of anything to do with the main bonding (or its absence) - BUT, as I also said, the regs do, in any event, require RCD protection of every circuit serving a bathroom, whether or not the room has supplementary bonding and whether or not the installation has main bonding.

There is therefore no doubt that the RCD protection required in any bathroom (regardless of everything else) is not present, hence a non-compliance with BS 7671 - so the only issue is whether the person undertaking the EICR regards that as deserving a C3 or a C2 - and I strongly suspect you will find electricians in both of those camps.

By the way, you say that there is 'no main bonding', and there clearly can't be any bonding of a plastic supply pipe - but do you have a gas supply? If you do, that is very probably 'main bonded', in which case it would not even be true to say that your installation has "no main bonding".

Kind Regards, John

 

[EFLImpudence]

There is supplementary bonding in place in the bathroom with good continuity between metal pipes and from metal pipes to earth. However, the main water and gas bonds are not in place as both supplies are plastic.