Ring final in conduit

Doesn't that exception refer to installations that remain under the control of a skilled or instructed person?
I believe it does, but I presume plugwash's view is that the degree of such 'control' is at least as great when it's in the OP's home as it would be in any other situation. The whole 'exception' seems a bit daft, anyway, since 'being in control of the electrical installation' probably does not usually mean much in terms of 'being in control' of those who might drill holes through concealed wiring!

In context, this is obviously all moot, because the OP does not intend to install any cables, only conduit!

Kind Regards, John
 
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Right, I see. I thought the whole install was to be conduit.

If you've just got drops in conduit, then I'd use PVC and put two on each box (for sockets) and one (or two) for light switches, depending on the gangs.

It's up to you, but I would fit 35mm boxes for the sockets and 25 for the switches. Give yourself a bit of breathing space when wiring up. Also, it allows you to fit dimmers or flat-plate accessories if you choose to do so.

If you want to omit RCD protection on the lighting, you need metal conduit drops for the switches and any wall lights, effectively earthed.
 
Thanks all for your input so far. One more question...
If you want to omit RCD protection on the lighting, you need metal conduit drops for the switches and any wall lights, effectively earthed.

Is there any advantage to not having RCD protection on the lighting circuits?
 
That might depend if you don`t mind being plunged in to darkness ?
Are going the have LED emergency lights with an automatic back up supply ?
What`s your location ? (although power supply can fail anywhere) ?
 
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That might depend if you don`t mind being plunged in to darkness ?
Once in a blue moon, and quite possibly during daylight hours! However, if it's a concern, and given that the OP is going to have an extensive rewire next year, the lighting circuits could be put on RCBOs - better, IMO, than having the hassle of having to protect buried cables!

Kind Regards, John
 
The concealed cables rule in the 17th edition of BS7671 does not apply to installations that are under the supervision of a skilled or instructed person.

The Guidance Notes state that a domestic premises could not be considered to be under the supervision of a skilled or instructed person, regardless of who lives there.
 
Have you read the disclaimer?

About them being guidance and the opinion of the IET, as the name Guidance Note suggests? Or are you referring to something else?

Either way it gives some insight into the intent, and you would have to question how a domestic premises could possibly be considered to be under the effective control of a skilled or instructed person - unlike a workplace.
 
Either way it gives some insight into the intent ...
Yes, I think one has to assume that, even though BAS will keep reminding us (technically correctly) that adherence to this guidance is not necessarily required in order to achieve compliance with the regs.
... and you would have to question how a domestic premises could possibly be considered to be under the effective control of a skilled or instructed person - unlike a workplace.
In the present context, and in terms of common sense, I'm not so sure about that. I would have been inclined to think that it would be easier to effectively 'instruct' the head of a domestic household (presumably the person 'in control of' it) as to where all the concealed cables were within that house than it would would be to instruct someone in a (perhaps very extensive) commercial /industrial workplace about the same matters.

Kind Regards, John
 
Thanks all for your input so far. One more question...
If you want to omit RCD protection on the lighting, you need metal conduit drops for the switches and any wall lights, effectively earthed.

Is there any advantage to not having RCD protection on the lighting circuits?

If the RCD's trip, all the lights stay on.
 
Yes, I think one has to assume that, even though BAS will keep reminding us (technically correctly) that adherence to this guidance is not necessarily required in order to achieve compliance with the regs.
Well, it's more, really, that the first thing they say, after the copyright info and edition history, i.e. the very first thing they say which is relevant to the actual content (and which is printed in bold type, I would have you note) is a disclaimer which says that whilst they think they are right it's down to the reader to satisfy themselves that they are, and that if they aren't right, even through gross incompetence, negligence, or deliberate misrepresentations, it's not their fault if you suffer through having taken notice of it.

Yes, of course the lawyers have been at work, but basically what the disclaimer says is that you cannot trust a single word which they have written, and that you must, if you wish to comply with the Regulations, read the Regulations yourself and make your own determination of what they require.



... and you would have to question how a domestic premises could possibly be considered to be under the effective control of a skilled or instructed person - unlike a workplace.
As JohnW2 says, in my house, and his house, it is perfectly reasonable to say that in the context of people drilling into walls there is a skilled person in control who can be relied upon to instruct others where they may or may not drill.

As for future people, no matter what plans either of us would have for making alterations before a planned departure, there is always the legendary bus which runs us over to be considered. But given how often people deride the concept of "safe zones", particularly the corner and ceiling ones, it's not unreasonable to suggest that if you are going to admit cables concealed there you could equally admit cables concealed elsewhere as long as they were adequately documented.


I would have been inclined to think that it would be easier to effectively 'instruct' the head of a domestic household (presumably the person 'in control of' it) as to where all the concealed cables were within that house than it would would be to instruct someone in a (perhaps very extensive) commercial /industrial workplace about the same matters.
Except the latter can have defined policies and procedures (apologies to ISO 900x devotees - I cannot be rsed to remember the difference :confused: ) which force people to go and find the documentation.
 
Except the latter can have defined policies and procedures (apologies to ISO 900x devotees - I cannot be rsed to remember the difference :confused: ) which force people to go and find the documentation.
Yes, they can/may have such policies/procedures, and they can/may have documentation, but the exceptions in BS7671 we're discussing require neither of those - only that the premises are under the control of people who are 'skilled or instructed'.

Kind Regards, John
 
...the lighting circuits could be put on RCBOs - better, IMO, than having the hassle of having to protect buried cables!

I like this idea.
I was already going propose some non-RCD circuits (freezer, boiler etc). If I understand correctly, I can have a split CU with one half of the circuits protected by a RCD "main switch" and the other with a standard main switch. The lights would go on the non-RCD switch side but use an RCBO, right?
 
...the lighting circuits could be put on RCBOs - better, IMO, than having the hassle of having to protect buried cables!
I like this idea. I was already going propose some non-RCD circuits (freezer, boiler etc). If I understand correctly, I can have a split CU with one half of the circuits protected by a RCD "main switch" and the other with a standard main switch. The lights would go on the non-RCD switch side but use an RCBO, right?
In this day and age, unless you went for all RCBOs (with just a main switch), which some would advocate, the next-best is probably to have a so-called "high integrity CU" - that has a main switch and two RCDs - so you have three groups of circuits - one group on each of the two RCDs and the third, with just the main switch, for 'unprotected' circuits and/or RCBOs.

Kind Regards, John
 
Except the latter can have defined policies and procedures (apologies to ISO 900x devotees - I cannot be rsed to remember the difference :confused: ) which force people to go and find the documentation.
You also have to have a culture in the organisation that makes those policies things that will actually be followed rather than things to pay lip service to when a sufficiently high level boss is looking and ignore otherwise.

Indeed I would argue that a homeowner is far more likely to be able to exert effective control over who drills holes in their home than many buisnesses are able to exert over their premises.
 

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