cavity wall

[kellogs64]

Hi all
Are you still allowed to run cables in a cavity wall to wire a conservetry to conform to 17th edition amedndmant 1
many thanks for your help,if you could direct me to the relevent page in the wiring guides would be even better.

 

[MarkieSparkie]

There is no specific regulation that forbids an installer installing a cable within a cavity wall. However BS 7671:2008+A1:2011 and The Building Regulations:2000+A:2010 highlight a number of reasons why this practice is undesirable:

The cable may be damaged during installation - BS 7671:2008+A1:2011, 522.8.1 refers.

The cable lacks support and also damage may occur due to the cable's own weight - BS 7671:2008+A1:2011, 522.8.4 refers.

Thermoplastic insulated and sheathed cables (PVC/PVC) in contact with polystyrene may cause the plasticizer within the insulation to migrate, leading to softening of the cable sheath - BS 7671:2008+A1:2011, 522.5.3 refers.

Cables installed within thermal insulation will have their current carrying capacity significantly reduced, which may require cable sizes to be increased - BS 7671:2008+A1:2011, 523.9 refers.

The cable may be attacked by flora and fauna - BS 7671:2008+A1:2011, 522.9 refers.

The cable may be in contact with the outer and inner wall thereby providing a route for water - Approved Document C Building Regulations refers.

From above, it is easy to see that cables should not normally be installed in external cavity walls, but where it has to be done the installation designer may well judge that Mineral-Insulated Copper Sheathed (MICS) cable is a suitable choice in such a location providing its selection and erection complies with BS 7671:2008+A1:2011.

 

[kellogs64]

would running singles through pvc conduit fix it rather than mineral insulated,i dont fancy trying to use swa?

 

[MarkieSparkie]

would running singles through pvc conduit fix it rather than mineral insulated,i dont fancy trying to use swa?

Yeah, that would be fine if your going at right angles, bridging across the cavity, but very difficult to run horizontal or vertical in the cavity.

 

[kingeri]

Can't add much to what Markie said (as usual!). I tend to view cavity walls as a no-no unless it's a last resort. If there really is no option then go with armoured!

 

[kellogs64]

got to be a better way than swa or mi , anyone else got any ideas

 

[Guitarist]

Surface mount in trunking if you can't channel the wall, or go under floor. Absolutely no way I would run in cavity.

 

[huntos33]

Always do mine in PVC conduit normally drop down in the room the conserveatorys built off drill through and fit a socket and tube from here, or wire back to back off exsiting socket and so on

 

[kellogs64]

Always do mine in PVC conduit normally drop down in the room the conserveatorys built off drill through and fit a socket and tube from here, or wire back to back off exsiting socket and so on

conduit on show ?

want a system thats not on view ie trunking,conduit.theres got to be a more suitable cable than swa or mi ?

how much do you charge to wire a coservatery roughly

 

[telectrix]

Surface mount in trunking if you can't channel the wall, or go under floor. Absolutely no way I would run in cavity.

i generally use pvc conduit laid on top of the fibreglass in the cavity of the dwarf walls. no way would a customer allow surface wiring. under floor is only an option if i can get in before the screed is laid.

 

[kellogs64]

i generally use pvc conduit laid on top of the fibreglass in the cavity of the dwarf walls. no way would a customer allow surface wiring. under floor is only an option if i can get in before the screed is laid.

how much would you charge roughly?

good idea aswell

 

[telectrix]

i charge between £250 and £350 for most. that's allowing for 2 visits, 1st/2nd fix.

 

[kellogs64]

is that for two double sockets and a light ?

next i will be asking for your phone number lol ?

thanks for your input really appritiate it

 

[telectrix]

i usually fit 2 twin sockets and a wall light or 2. light/s via a 3A FCU off the circuit feeding the sockets.

 

[kellogs64]

thanks again for your advice

is'nt there a cable you could lay in there,somthing inbetween pvc/pvc and swa

would i be better talking to my wholeseller,surley laying a cable between bricks wouldnt need the protection of swa,after taking into account the other facters