Cable routes

[riveralt]

Start a new thread!!!

You should comply with the current BS7671 - you have got one haven't you?
BTW its 50mm from front and rear - so I doubt if it is going to be more than 50mm. But why do you ask this question?

You will also need access to the Building Regulations Approved documents relevant to work you are doing.

Be guided by what you Local Authority Building Control Inspector says.

 

[ban-all-sheds]

Old thread I know and not the OP refers to 16th ed. Any changes to this in the 17th...?

Do you have any idea how alarming it is to think that you're wiring a house and you don't have copies of the 17th regulations and On-Site Guide?

If you've already applied for Building Regulations approval, what did you say would be the way you'd comply with P1?

If you've yet to apply, what do you plan to say?

 

[JamesNorton01]

Thanks for your advice....

As it happens I'm an architect and the house in question is one I am building and have designed myself.

When I say am doing the wiring "I" am referring to the organisation and strategic design of it and in this case specifically the work sequencing and more specifically the arrangement of battening. Whilst I will be not doubt helping pulling through cabling etc the 'competent person' will be one of two electricians that I work with. Perhaps I should have said "we". However neither were 100% on this either. Building Control the same.

It would seem with reference to ADL Part P, the 17th edition that the solution is technically compliant as all the proposed routes have 50mm cover front and back, (the lining construction we are referring to applies to external timber frame walls and so 50mm front and back is no an issue), as such technically "I" could wire outside these zones, but as far as can tell I am not proposing to. The situation at the doors is a bit clunkier and although 50mm cover is retained 'am suggesting 37 channel as a belt and braces, (earthed conduit would seem overkill...?).

Having said that its clearly more than that about 'technically compliant' and hoped for some constructive suggestions.

Plan B would be to stay in the 150 zone at the wall head of course and drop down, (would prefer to stay out of the floors).

Thanks again for your help so far...

J

PS why start a new thread this seems to be essentially the same question but a different wall build up...? Nothing worse than lots of threads all asking the same question surely?

 

[ban-all-sheds]

the 'competent person' will be one of two electricians that I work with. Perhaps I should have said "we". However neither were 100% on this either.

I suggest you find new electricians who actually know what the regulations say.

 

[JamesNorton01]

And prey tell what do 'the regulations' say to this particular question oh great high priest of electrical knowledge...?

J

PS with regard to knowing what they say:

It would seem with reference to ADL Part P, the 17th edition that the solution is technically compliant...

...Having said that its clearly more than that about 'technically compliant' and hoped for some constructive suggestions.

 

[JamesNorton01]

edited

 

[ban-all-sheds]

522.6.6 A cable concealed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition shall:
(i) incorporate an earthed metallic covering which complies with the requirements of these Regulations for a protective conductor of the circuit concerned, the cable complying with BS 5467, BS 6346, BS 6724, BS 7846, BS EN 60702-1 or BS 8436, or
(ii) be enclosed in earthed conduit complying with BS EN 61386 and satisfying the requirements of these Regulations for a protective conductor, or
(iii) be enclosed in earthed trunking or ducting complying with BS EN 50085 and satisfying the requirements of these Regulations for a protective conductor, or
(iv) be mechanically protected against damage sufficient to prevent penetration of the cable by nails, screws and the like, or
(v) be installed in a zone within 150 mm from the top of the wall or partition or within 150 mm of an angle formed by two adjoining walls or partitions. Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear. Where the location of the accessory, point or switchgear can be determined from the reverse side, a zone formed on one side of a wall of 100 mm thickness or less or partition of 100 mm thickness or less extends to the reverse side.

522.6.7 Where Regulation 522.6.6 applies and the installation is not intended to be under the supervision of a skilled or instructed person, a cable installed in accordance with Regulation 522.6.6 (v), and not complying with Regulation 522.6.6 (i), (ii), (iii) or (iv), shall be provided with additional protection by means of an RCD having the characteristics specified in Regulation 415.1.1.

522.6.8 Irrespective of the depth of the cable from a surface of the wall or partition, in an installation not intended to be under the supervision of a skilled or instructed person, a cable concealed in a wall or partition the internal construction of which includes metallic parts, other than metallic fixings such as nails, screws and the like, shall:
(i) incorporate an earthed metallic covering which complies with the requirements of these Regulations for a protective conductor of the circuit concerned, the cable complying with BS 5467, BS 6346, BS 6724, BS 7846, BS EN 60702-1 or BS 8436, or
(ii) be enclosed in earthed conduit complying with BS EN 61386 and satisfying the requirements of these Regulations for a protective conductor, or
(iii) be enclosed in earthed trunking or ducting complying with BS EN 50085 and satisfying the requirements of these Regulations for a protective conductor, or
(iv) be mechanically protected sufficiently to avoid damage to the cable during construction of the wall or partition and during installation of the cable, or
(v) be provided with additional protection by means of an RCD having the characteristics specified in Regulation 415.1.1.

NOTE: If the cable is installed at a depth of 50 mm or less from the surface of a wall or partition the requirements of Regulation 522.6.6 also apply.

 

[holmslaw]

..

 

[JamesNorton01]

Much appreciated.

...So technically compliant as more than 50mm below. The only bit that gets a bit flakey is the metal mechanical protection as a belt and braces which perhaps creates more problems than it solves in terms of compliance...

...but then again like I said its not always just about compliance...

The other advantage apart from cable length (and therefore size and therefore cost), is that my battens could just run horizontally and could incorporate additional battens at worktop/dado cupboard/picture rail height and the plasterboards would fix vertically which is easier for one man boarding...

..thoughts...?

J

(Are you a quick typer or do you have a digital copy...? Former would be very handy in the office...)

 

[JamesNorton01]

Timber frame with a service zone lining is pretty typical. It allows a wiring zone and protects the VCL. Plasterboard either side of the batten is good practice as it allows firm fixing of the VCL and protection to the frame.

...but of course as soon as I say i'm an architect you have to have a go...


J

 

[bernardgreen]

And in each of the paragraphs is a clause which gives permission to use an RCD to protect cables which are not installed in compliance with the other clauses in the paragraph.

 

[JamesNorton01]

...then again there's ceilings which mention 50mm from the top and bottom of joists if through joists and as far as I can tell are not explicit about depths in other locations, and aren't mentioned as a safe zone (other than 150mm from the edge), but showing in one illustration wiring resting on the top side of plasterboard when between joists... ...which when read with the wall sections... causes even more ambiguity...

J

 

[riveralt]

...then again there's ceilings which mention 50mm from the top and bottom of joists if through joists and as far as I can tell are not explicit about depths in other locations, and aren't mentioned as a safe zone (other than 150mm from the edge), but showing in one illustration wiring resting on the top side of plasterboard when between joists... ...which when read with the wall sections... and causes even more ambiguity...

J

And in each of the paragraphs is a clause which gives permission to use an RCD to protect cables which are not installed in compliance with the other clauses in the paragraph.

If I were designing a new build each circuit would be protected by an RCBO - stop whinging about more or less cable - stop looking for excuses - do it right or don't do it at all.

Or are you just trolling along

 

[JamesNorton01]

I am not trolling and resent the suggestion.

The cable price is a lesser issue, it is better to have shorter cable runs in any event.

More relevantly my battens will preferably run horizontal ie counter to the studs and so dropping down will give me head aches galore.

As far as I can tell what "I" am doing is within the regs because it is a) deeper than 50mm and b) orthogonal with the accessories.

Agreed...? or not ?

So putting the quasi offensive stuff to one side the RCBO seems reasonable, but having said that so far I'm up to 30+ ways....

J

 

[bernardgreen]

Having said that so far I'm up to 30+ ways..

In which case consider a "main" consumer unit next to the meter that feeds sub mains to small consumer units around the house. Use SWA cable or mechanically protected cable for the submains to avoid the need for RCD protection on the sub-main cables. Have RCD or RCBO protection on the circuits out of the other consumer units.

Two or three sub mains through the house even in SWA is less trouble than a large bunch of 30 or more cables converging on one consumer unit.