Hi all, I want to extend my ring main through a wall to another room. Is it acceptable to pick-up from an existing socket and run the cable behind the skirting then through the wall to the new socket? distance will be about 2 mtr. The room has concrete floor with drops from the roof which is inaccessible, single story so would have to rip the roof up.
Match
It's OK so long as the cable is running at the same height as the socket. Whilst you can do what you like within 150mm of the ceiling, this is not the case for the floor (basically because people tend to fit skirting boards and the like in this area and could therefore damage the cable. Going through the wall into the back of the socket is fine, it's just that you can't go down from the existing socket and then across, only straight across.
Alternatively you could run behind the skirting if there was enough room to put the cable under metal protection which is earthed.
Hope this helps.
Fash
Thanks for the quick reply Fash. The existing socket is 100mm above the skirting so I will have to make the drop down to the centreline of the skirting, around an internal corner then through the wall. I assume from your reply that if I chase the wall behind the skirting and cover in grounded metal not plastic? I should be OK. Would I also need to go through the wall in metal?
Match
If the new socket is to be at the same height as the one that you're taking the spur from then it will be easier not to drop down but to run the cable on a direct horizontal line between the two sockets.
It needs to be thick metal that you couldn't easily drill or nail through. Steel conduit is OK, but the thin metal capping certainly isn't.
Protection is needed where the cable is less than 50 mm from either surface of the wall AND is not in the defined horizontal safe zone.
This isn't quite true, the point is if the protection is earthed then you are safer as you're always in contact with earth before reaching the live and therefore the low resistance path won't include the operator. I have reproduced the relevant bit from th regs below.
Protection, as permitted by Regulation 522-06-06 (i), (ii) and (iii), may be provided in a number of ways. The cable may be protected by an earthed metal conduit, trunking or ducting satisfying the requirements of BS 7671 for a protective conductor, or the cable should incorporate an earthed metal sheath complying with the requirements of BS 7671 for a protective conductor of the circuit concerned. Alternatively, mechanical protection sufficient to prevent penetration of the cable by screws or nails may be used.
The point is that it is very hard to satisfy the mechanical penetration requirement hence why it's earthed.
I agree with Andy here except that you don't have a problem on the side of the wall where your new socket is since the cable will be vertically below the fitting and therefore in a safezone.
Take a look at
Fash
I'm not sure exactly which bit you're saying isn't quite true. I accept it's a little simplified but maintain that metal capping (earthed or not) does not provide adequate protection. 522-06-06 (iii) requires earthed conduit, trunking or ducting (satisfying the requirements for a CPC) and capping is none of those things. But you're quite right to point out that "mechanical protection sufficient to prevent penetration of the cable by nails, screws and the like" would not need to be earthed.
There are also the options of using cables incorporating an earthed covering, or concentric cables as permitted in 522-06-06 (i) and (ii). We discussed that possibility recently in this thread
The bit you reproduced was copied from the NICEIC page you cited and not from BS 7671, so is not "the regs".
FAOD, here's the whole of 522-06-06 (again):
*522-06-06* A cable concealed in a wall or partition at a depth of less than 50 mm from the surfaces 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 of insulated concentric construction complying with BS 4553-1, BS 4553-2 or BS 4553-3, or
(iii) be enclosed in earthed conduit, trunking or ducting satisfying the requirements of these Regulations for a protective conductor, or be mechanically protected sufficient to prevent penetration of the cable by nails, screws and the like, or
(iv) 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.
Incidentally, from June 2008 the 17th Edition is likely to allow unprotected runs outside the safe zones provided that the circuit is 30 mA RCD protected and "the normal methods of protection [...] cannot be employed".
Mmm, OK - I see what you're getting at. Fair point.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.