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.

 

[DPG]

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.

Pretty sure it's been stated that it will be corrected in future versions. Or have I imagined that?

 

[Spoon]

Pretty sure it's been stated that it will be corrected in future versions. Or have I imagined that?

No, there was a thread about it a bit ago, but then there are conflicting threads to say that it wont.

 

[Spoon]

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.

There is no mention of BS 7288 in either the 17th or 18th edition.

 

[DPG]

No, there was a thread about it a bit ago, but then there are conflicting threads to say that it wont.

I might just add it in biro to my copy.

 

[westward10]

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.

The 17th Ed never suggested the type of device which should be used just that it should be 30ma with quoted tripping parameters.

 

[pc1966]

No, there was a thread about it a bit ago, but then there are conflicting threads to say that it wont.

One of the IET Q&A had an answer, in a rather convoluted way, saying:

"RCDs to BS 7288 are not recognised for use as an RCD by BS 7671:2018. See Regulation Group 531.3.4.

Clause 1 of BS 7288:2016 states “SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.”

Further, Clause 0 of BS 7288:2018 states the devices are only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit), nor would they be recognised for additional protection against fire due to short circuits in appliances or flexible cables connected to the socket-outlet or connection unit.

However, there is nothing to stop accessories containing SRCDs to BS 7288 being fitted in electrical installations complying with BS 7671, as they comply with the relevant standards, although as stated the RCDs within them cannot be recognised for the functions of fault protection or additional protection for the purses of BS 7671."

Not having a copy of BS 7288 to look at, the only thing that I can really see from the above is the rather odd statement that they cannot provide 'fault protection', only shock protection. But why that is has not been elaborated anywhere I have seen.

I don't know if it comes down to breaking capacity, etc, but I would be happier with one for shock protection than not, assuming the circuit is otherwise capable of meeting disconnection on the MCB/Zs results, etc.

 

[Mike Johnson]

I might just add it in biro to my copy.

No No No add it in pencil then you can rub it out and modify it when they change their minds........... again.

 

[loz2754]

One of the IET Q&A had an answer, in a rather convoluted way, saying:

"RCDs to BS 7288 are not recognised for use as an RCD by BS 7671:2018. See Regulation Group 531.3.4.

Clause 1 of BS 7288:2016 states “SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream of the SRCD.”

Further, Clause 0 of BS 7288:2018 states the devices are only suitable for additional protection against direct contact, and therefore cannot provide fault protection (e.g. where disconnection times cannot be met in a circuit), nor would they be recognised for additional protection against fire due to short circuits in appliances or flexible cables connected to the socket-outlet or connection unit.

However, there is nothing to stop accessories containing SRCDs to BS 7288 being fitted in electrical installations complying with BS 7671, as they comply with the relevant standards, although as stated the RCDs within them cannot be recognised for the functions of fault protection or additional protection for the purses of BS 7671."

Not having a copy of BS 7288 to look at, the only thing that I can really see from the above is the rather odd statement that they cannot provide 'fault protection', only shock protection. But why that is has not been elaborated anywhere I have seen.

I don't know if it comes down to breaking capacity, etc, but I would be happier with one for shock protection than not, assuming the circuit is otherwise capable of meeting disconnection on the MCB/Zs results, etc.

That statement says they cannot be used for fault protection or additional protection. Yet they contradict themselves by saying that they can be fitted. What would be the point of fitting an RCD that provides neither fault protection nor additional protection.
The Connections magazine stated that this omission from BS7671 was an error and will eventually be corrected.
Total shambles as usual.
Because of the controversy surrounding these BS7288 socket RCDs, I personally will not fit them. Which is a shame because they definitely do have a use in my opinion.

 

[DPG]

That statement says they cannot be used for fault protection or additional protection. Yet they contradict themselves by saying that they can be fitted. What would be the point of fitting an RCD that provides neither fault protection nor additional protection.
The Connections magazine stated that this omission from BS7671 was an error and will eventually be corrected.
Total shambles as usual.
Because of the controversy surrounding these BS7288 socket RCDs, I personally will not fit them. Which is a shame because they definitely do have a use in my opinion.

I knew I'd seen it somewhere. Ta.

 

[pc1966]

That statement says they cannot be used for fault protection or additional protection. Yet they contradict themselves by saying that they can be fitted. What would be the point of fitting an RCD that provides neither fault protection nor additional protection.

Ah, because they can provide supplementary protection.

What does that mean in practice? Well we could ask the IET and probably get some equally convoluted explanation as for the original Q&A.

Why they don't just fix BS7288 to provide what is needed I don't know.

Looking at the "PowerBreaker" (Greenbrook) range's data sheet, and the TimeGuard ones (though might be same manufacturer) they claim 1.5kA breaking capacity, but I suspect the 13A fuse would peak current limit to below that even if you have a very high PFC supply.

For example, the 16A BS88 fuse plot I have (as I don't have the same information for the BS1362 13A fuse) has it limiting the peak current to 1.5kA for all PFC up to around 10kA, so it can break as much as it's fuse would let through. Which sounds like a sensible design.

 

[Jm1980]

This seems a crazy situation that really ought to have been sorted.

It seems we don't really have a consensus across the industry about whether an RCD spur to BS7288 can be used to provide protection to a bathroom.
Technically it appears as though it is fine and a departure on the cert is what a lot are doing and indeed being recommended to do via their scheme provider.
It makes me uneasy to use an RCD spur especially as no supplementary bonding, even though I've seen this dozens of times for the purpose of getting rcd protection of bathroom circuits.

On a side note, i look after a factory full of BS88 fuseboards where socket outlets are to BS7288, is it therefore the case that the 18th has made these circuits non complaint/worthy of a departure note, the next time one of the SRCD's needs replacing?

 

[Ian1981]

Extract from a BS 7288 tech sheet

 

[pc1966]

Extract from a BS 7288 tech sheet

Does anyone have definitions for additional protection and for supplementary protection by any chance?

They are not defined in the opening chapter of the 18th regs.

 

[Ian1981]

Does anyone have definitions for additional protection and for supplementary protection by any chance?

They are not defined in the opening chapter of the 18th regs.

Makes you wonder what the point of an rcd spur/socket is when you require an rcd upfront of it anyway?

 

[pc1966]

Makes you wonder what the point of an rcd spur/socket is when you require an rcd upfront of it anyway?

Exactly, if you already have RCD protection then why would you fit one?