re-wired in cavity??

[martysparky]

I called at a house today to do a little job.

The clients house had recently had a total rewire he mentioned that a switch cable had been dropped through the floor boards, down the cavity and back through the wall to the switch.

My thought is that cannot be done inside Bs7671 unless simply replacing a cable following its designed route but that would not be the case here.

I guess, however, that would be the reason to replace a cable I.e. rodent damage as they can get in cavities and so can water and subsequently run down the cable to the switch.

What would be the best practice with this one?

Suggestions would be of interest.

Cheers.

 

[albi]

Cables should normally not be run in external cavity walls. But if you have to a sheathed mineral-insulated copper cable may be judged by the installation designer to be suitable for that location

 

[bugsy]

I'm not aware of any regulations which prohibit the installations of cables in cavity's however due consideration should be given to the building reg's regarding passage of moisture, passage of sound and the effects of cavity insulation. although I may be wrong -

 

[markythesparky]

I believe the last post sums it up.

There is no issue with this under BS7671 but there is under building regs.

 

[Darkwood]

Cavity wall are prone to rubble falling and any cable passing through a cavity wall must have a appropriate protection e.g. ducting pipe swa micc as well as fire block to seal entry and exit, so i assume if said cable is run through the cavity vertically is must fall under the same regulations in that it is either mechanically protected in itself or is run through conduit, trunking etc.

 

[albi]

SNAGS AND SOLUTIONS SNAG 18

reg 522.5.5
reg 522.8.1
reg 522.8.4
reg 522.9.1
reg 522.10.1
reg 523.7

 

[Darkwood]

Albi are you inventing Regs where is reg 522.5.5, although thx for supporting my post with the relevent regs.

 

[albi]

SORRY REG 522.5.3 (slip of the finger)

MATERIALS LIABLE TO CASE MUTUAL OR INDIVIDUAL DETERIORATION OR HAZARDOUS DEGRADATION SHALL NOT BE PLACED IN CONTACT WITH EACH OTHER

 

[sparks1234]

Not supported properly

 

[TimmyB]

If you can somebody in there to clip it every 9in - Problem sorted

Tim

 

[martysparky]

If you can somebody in there to clip it every 9in - Problem sorted

Tim

Clips would not protect the cable or switch from water or rodents or falling debris though!
simply best to avoid external cavities unless suitably protected ( intended for use )

 

[lj.l]

SNAGS AND SOLUTIONS SNAG 18

reg 522.5.5
reg 522.8.1
reg 522.8.4
reg 522.9.1
reg 522.10.1
reg 523.7

agree .blown in insulation will break down the pvc on the cable and leave it like it has overheated, brittle ,Ive seen it happen ,may not be a problem now but in the future.

 

[cbw]

I am sorry to bring this old thread up!

I have been looking through the old threads and cannot find a definative answer on SWA in cavitys.

I have really struggled to find a cable route for a sub supply and ended going into an existing hole in a cavity wall at ground floor ceiling level.

I have then pulled this up into the loft.

How bad is this?

 

[Farmelectrics]

albi i agree but once done a conservatory were i had to run in cavity no other choice how would you be able to get to sockets on a brick wall in conservatory

 

[SPARTYKUS]

If you can somebody in there to clip it every 9in - Problem sorted

Tim

I've heard some breeds of dogs are very intelligent, if you could catch one early on and train the little blighter and hold back on feeds, maybe, just maybe for a year ......

 

[johnboy6083]

I am sorry to bring this old thread up!

I have been looking through the old threads and cannot find a definative answer on SWA in cavitys.

I have really struggled to find a cable route for a sub supply and ended going into an existing hole in a cavity wall at ground floor ceiling level.

I have then pulled this up into the loft.

How bad is this?

i dont think its that bad to be honest. ive seen SWA buried directly in concrete, ive seen it smothered with lagging in a power station, and left loose in cable pits, constantly submerged.

it wouldnt be my first choice for a route, but if i was stuck, then i would consider. at least its mechanically protected