New work in old bathroom

[NozSpark]

RCD's are not there to protect you from voltages which may exist on the earth wire,,, your low R2 continuity is for that!

RCD's protect you from voltages which travel from L to E (either directly or indirectly)

 

[spinlondon]

An RCD it there to detect an imbalance in current flowing in and out. This difference could be flowing to earth but does not have to flow down a CPC. Since a CPC is never disconnected from the rest of the installation an RCD would not stop a fault for example on a lost neutral on a TN-C-S system.

Sorry I thought we were dealing with BS7671 and the requirements for RCD protecting circuits in special locations.

Not the requirements of ESQCR2009.

I reiterate, I was under the impression that the point of an RCD was to prevent electricution in the event of earth faults (not supply neutral faults, which as you have pointed out, it would not protect against).

Are you stating that RCD protection is not required as per the requirements of BS7671, because there should be bonding in place?

 

[kme]

OK - I`m going to wade in here.......... (where`s me hard hat!!!)

Spin - I understand your point regarding a fault upstream of the RCD not being detected; but if the installation is incapable of clearing the fault through correct operation of the existing protective device(s), then the installation should not be altered until the protective measures have been altered or modified as necessary to provide disconnection in the event of a fault....but I digress.

We are not actually debating THAT point. If we were to start doing that; EVERY question asked on this forum would need to have pre-verified earthing & bonding, protective devices, tripping times, etc; BEFORE we ever discussed the works in question. We, on this forum, MUST draw some basic conclusions from posts such as this:

primarily: we are answering the question that has been asked: NOT "what if"`ing every suggestion.

We cannot delve into all the idiosyncracies of a particular installation. We take it as read that the O/P, as someone who is carrying this work out, has already verified the veracity of the pre-existing protective devices. Therefore, to answer his question - as Noz & I have suggested.

Hope that makes sense?

KME

 

[spinlondon]

RCD's are not there to protect you from voltages which may exist on the earth wire,,, your low R2 continuity is for that!RCD's protect you from voltages which travel from L to E (either directly or indirectly)

That's exactly what I was led to believe.

Which is why I pointed out that placing an RCD part way along a circuit, or on a ring would allow such voltages to bypass the RCD.

 

[ianmacd]

Sorry I thought we were dealing with BS7671 and the requirements for RCD protecting circuits in special locations.Not the requirements of ESQCR2002.

I reiterate, I was under the impression that the point of an RCD was to prevent electricution in the event of earth faults (not supply neutral faults, which as you have pointed out, it would not protect against).

Are you stating that RCD protection is not required as per the requirements of BS7671, because there should be bonding in place?

Are you reading the same forum as me? I never said it was not needed just pointed out that any circuit starting from an RCD and/or over current protection on an existing final circuit will be a new circuit.

I also never suggested we work to anything but 7671, I mearly used the lost neutral as an example of an earth fault that an RCD would not protect anyone from.

 

[spinlondon]

OK - I`m going to wade in here.......... (where`s me hard hat!!!)Spin - I understand your point regarding a fault upstream of the RCD not being detected; but if the installation is incapable of clearing the fault through correct operation of the existing protective device(s), then the installation should not be altered until the protective measures have been altered or modified as necessary to provide disconnection in the event of a fault....but I digress.

We are not actually debating THAT point. If we were to start doing that; EVERY question asked on this forum would need to have pre-verified earthing & bonding, protective devices, tripping times, etc; BEFORE we ever discussed the works in question. We, on this forum, MUST draw some basic conclusions from posts such as this:

primarily: we are answering the question that has been asked: NOT "what if"`ing every suggestion.

We cannot delve into all the idiosyncracies of a particular installation. We take it as read that the O/P, as someone who is carrying this work out, has already verified the veracity of the pre-existing protective devices. Therefore, to answer his question - as Noz & I have suggested.

Hope that makes sense?

KME

Why are we installing RCDs?

If we are installing them because it is now a requirement of BS7671, would it not then seem appropriate to comply with those requirements?

BS7671 requires the circuit to be protected, not part of the circuit, or just a little bit of the circuit.

If you don't consider compliance with BS7671 as necessary, then why bother installing an RCD at all?

 

[ianmacd]

Why are we installing RCDs?If we are installing them because it is now a requirement of BS7671, would it not then seem appropriate to comply with those requirements?

BS7671 requires the circuit to be protected, not part of the circuit, or just a little bit of the circuit.

If you don't consider compliance with BS7671 as necessary, then why bother installing an RCD at all?

7671 requires that any new circuits or parts thereof being worked upon need rcd protection in certain circumstances and these can be satisfied with a stand alone RCD.

 

[spinlondon]

Are you reading the same forum as me? I never said it was not needed just pointed out that any circuit starting from an RCD and/or over current protection on an existing final circuit will be a new circuit.I also never suggested we work to anything but 7671, I mearly used the lost neutral as an example of an earth fault that an RCD would not protect anyone from.

Sorry, but your posts as I think I may have stated before are not very clear.

Now from what you have just posted, I understand that you are stating a circuit can start from a protective device on another circuit. Is this correct, and could you provide something from BS7671 that supports this?

 

[flyingspark]

Right then, quite a few different opinions so far!

Ok so back to my 2 questions,-

I was talking about moving from the current cu to a new rcd enclosure, one of the lighting circuits which amongst other rooms supplies the bathroom. This circuit is the only circuit I would need to alter when installing the vanity light above the sink. I noticed that the SELV and extractor are supplied via one of the socket circuits. Would I have to (to comform to 17th) move that socket circuit into the new rcd protected enclosure as well?

Unless I am mistaken the easyest option would be to put the new sink light on an RCD spur, installed (including control plate switch) outside the bathroom, supplied from a socket circuit. And as far as my involvement with the other bits in the bathroom, just advise client and note it on cert?

thanks for all the input so far.

 

[kme]

Why are we installing RCDs?If we are installing them because it is now a requirement of BS7671, would it not then seem appropriate to comply with those requirements?

BS7671 requires the circuit to be protected, not part of the circuit, or just a little bit of the circuit.

If you don't consider compliance with BS7671 as necessary, then why bother installing an RCD at all?

I don`t believe I said that, mate?

IF the customer won`t upgrade box, and rewire lighting circuit as a whole, which is the ideal outcome, what`s the next option? Say "Sorry missus, I`m not doing it"?. In this instance, the O/P will have installed NOT ONLY his "new" work to the bathroom IAW 7671; but also the pre-existing bathroom wiring as well. If the bathroom is required to have ALL equipment protected by an RCD; the O/P will have complied by using the RCD F/S, surely?

KME

 

[NozSpark]

RCD's are not there to protect you from voltages which may exist on the earth wire,,, your low R2 continuity is for that!RCD's protect you from voltages which travel from L to E (either directly or indirectly)

That's exactly what I was led to believe.Which is why I pointed out that placing an RCD part way along a circuit, or on a ring would allow such voltages to bypass the RCD.

Are we reading the same thing here??

Unless you have an open cct CPC then there should be no more than 50v on the CPC if there is an upstream fault, and with supp bonding (which this installation should have) all the exposed metal work would still be at the same potential no matter what

 

[spinlondon]

7671 requires that any new circuits or parts thereof being worked upon need rcd protection in certain circumstances and these can be satisfied with a stand alone RCD.

I'm not aware of any Regulation in BS7671 that states such.

There is only one Regulation that refers to protecting circuits with an RCD in BS7671, and I don't recall there being any mention of stand alone RCDs that can protect just part of those circuits. Perhaps you could provide the Regulation number?

 

[spinlondon]

Are we reading the same thing here??Unless you have an open cct CPC then there should be no more than 50v on the CPC if there is an upstream fault, and with supp bonding (which this installation should have) all the exposed metal work would still be at the same potential no matter what

So we don't need RCD protection then?

 

[spinlondon]

I don`t believe I said that, mate?IF the customer won`t upgrade box, and rewire lighting circuit as a whole, which is the ideal outcome, what`s the next option? Say "Sorry missus, I`m not doing it"?. In this instance, the O/P will have installed NOT ONLY his "new" work to the bathroom IAW 7671; but also the pre-existing bathroom wiring as well. If the bathroom is required to have ALL equipment protected by an RCD; the O/P will have complied by using the RCD F/S, surely?

KME

Sorry I thought we were working to the 17th edition now.

The requirement to protect equipment went out the window when the 17th came in.

The requirement now is to protect the circuits not the equipment.

 

[ianmacd]

Are you just looking for arguments spinlondon?

 

[spinlondon]

Are you just looking for arguments spinlondon?

I believe that I am pointing out the requirements of BS7671.

It is you that is arguing with me.

By the way, any chance of you providing the Regulations, or something from BS7671 to support your arguments. I have at least had the courtesy do do so in support of mine.

 

[ianmacd]

I believe that I am pointing out the requirements of BS7671.It is you that is arguing with me.

By the way, any chance of you providing the Regulations, or something from BS7671 to support your arguments. I have at least had the courtesy do do so in support of mine.

So we are all arguing with you?

Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s).

So anything protected by a FCU or other overcurrent device is classed as a circuit. Therefore any requirement for RCD will only apply to a circuit after the new FCU that is proposed to be installed.

 

[spinlondon]

So we are all arguing with you?So anything protected by a FCU or other overcurrent device is classed as a circuit. Therefore any requirement for RCD will only apply to a circuit after the new FCU that is proposed to be installed.

At last something from the Regulations.

That's the definition of a circuit.

Supplied from the same origin, are you saying that the origin is the FCU, and not the ring circuit protective device?

Now how about 314 Division of Installation?

How would having two circuits protected by the one protective device meet those requirements?

How about Appendix 15, which states that circuits start and finish at Distribution Boards?

 

[ianmacd]

At last something from the Regulations.That's the definition of a circuit.

Supplied from the same origin, are you saying that the origin is the FCU, and not the ring circuit protective device?

Now how about 314 Division of Installation?

How would having two circuits protected by the one protective device meet those requirements?

How about Appendix 15, which states that circuits start and finish at Distribution Boards?

Yes the origin is now the FCU.

You think the circuits start at the CU and there is nothing before that? Following that quasi-logic(sic) then the CU should never be installed as its part of a circuit that starts at a transformer.

314. That is why we are fitting the FCU/other device to separate the circuits.

As for Apdx 15. That I believe is a copy and paste error as radials do not start AND finish at a CU.

I am not getting drawn into another debate with you over this as you seem to be arguing with every answer that is not the same as yours and to the extent you are doing it is unhelpful and destructive. The OP seems happy with these suggestions so I am unsure why you are persevering with this crusade apart from to give you something to do.

 

[spinlondon]

Yes the origin is now the FCU.You think the circuits start at the CU and there is nothing before that? Following that quasi-logic(sic) then the CU should never be installed as its part of a circuit that starts at a transformer.

314. That is why we are fitting the FCU/other device to separate the circuits.

As for Apdx 15. That I believe is a copy and paste error as radials do not start AND finish at a CU.

I am not getting drawn into another debate with you over this as you seem to be arguing with every answer that is not the same as yours and to the extent you are doing it is unhelpful and destructive. The OP seems happy with these suggestions so I am unsure why you are persevering with this crusade apart from to give you something to do.

It's not that I think the circuits start at the CU, it's what is described in Appendix 15 of BS7671.

How does feeding a circuit from another circuit comply with 314? I thought that one of the requirements of 314 was to minimize inconvenience in the event of a fault?

There was me thinking that it was a requirement to provide both overload and fault protection where there is a reduction in the current-carrying capacity of a conductor.

Does this mean that every fused spur off of a ring is a separate circuit?

How do you record the test results when issuing a certificate, or conducting a PIR?

Yes if you have an old copy of BS7671, and have not obtained the corrigenda then you will have those errors in Appendix 15, there are also a number of other errors that the corrigenda addresses.

I feel it is advisable to keep up to date with the regulations.

Is it my magnetic personality that draws you into these debates, or do you enter them of your own volition?

I will remind you, that it is you that has disagreed with me, so if any one is argumentative.......

The OP may well be happy with suggestions, I wonder if he will be happy to sign a document stating that his work complies with the Regulations, when in fact his work doesn't.

Producing a false instrument is considered quite a serious offence, and I doubt that a defence of some people told me on a forum will cut any ice.