cables in cavity dwarf wall unisnulated!

[Kiers1970]

My mate has just rang (honest Guv) says a building inspector has pulled him on the fact that he's run a conservatory ring main inside the cavity of the dwarf wall, which apparently will not be insulated.

Now I know cables in cavities which are insulated are a no-no, what are your views on this problem?


He's been told hes to run the cables on the inside of the wall, which is to be dot/dabbed???

Personally I don't see the problem with his original method... It's covered by rcd etc, I suggested if it is to be insulated that he de- rates the circuit..

 

[topquark]

It's against the building regs (and has been for some time). It allows water to bridge from the outside to the inside wall. The other thing is when this is done in the house wall the possibility exists for the home owner to add cavity wall insulation which will effectively derate the cables (which may not have been taken into account in the orig design).

 

[Kiers1970]

yes, understand that, but the cables do not go form one side of the wall to the other, they arent outside.

He can derate the circuit right now.

Come on , we all drill for cable to to go outside lights etc, do we all with out fail seal the holes? do we all use conduit to bridge the cavity?

 

[topquark]

yes, understand that, but the cables do not go form one side of the wall to the other, they arent outside.

He can derate the circuit right now.

Come on , we all drill for cable to to go outside lights etc, do we all with out fail seal the holes? do we all use conduit to bridge the cavity?

The cables may not go from wall to wall, but they will run over the top of the cavity ties and stop the water driping off down the cavity and allow it to run down the cables (with the possibility of it turning up in the nock out box!).

Going straight through the wall is not so likely to have this problem, and if the job is done thoughtfully you'll drill at a very slight down ward angle towards the outside wall.

 

[Kiers1970]

maybe he should clip them on the inside of the dwarf wall, i reckon they would be lying on the deck any how, I can see that they would be sitting on any wall ties, strewth, what a pain in't backside!

 

[topquark]

maybe he should clip them on the inside of the dwarf wall, i reckon they would be lying on the deck any how, I can see that they would be sitting on any wall ties, strewth, what a pain in't backside!

Pain in the 4rse I agree, but that's the rules. He could try arguing that they're down below DPC level, but don't hold your breath

 

[Kiers1970]

Glad it's not my problem...Anyhow, just shows you the NIC give Full scope Dom Installer to anyone, he asked me how to wire a 2 way switch last year, and didn't know how to wire looped from switch to switch.

 

[telectrix]

so what do you do in a conservatory dwarf wall that's going to be left as bare brick. surface wirig? customer will love that in his £15,000 sun lounge.

 

[Kiers1970]

so what do you do in a conservatory dwarf wall that's going to be left as bare brick. surface wirig? customer will love that in his £15,000 sun lounge.

Thats EXACTLY what i said to him.....(before he told me it was going to be plastered.

 

[topquark]

so what do you do in a conservatory dwarf wall that's going to be left as bare brick. surface wirig? customer will love that in his £15,000 sun lounge.

Exactly, pain in the 4rse it is. Even if you use plastic skirting or dado trunking you've still got to get into the socket from there (especially if you're fixing at 450mm ).

 

[Thomas123]

your allowed to run cables in a cavity if they are mechanicallly protected and a fixed to inner skin. ensuring that no bridging occurs. (i think)

 

[Kiers1970]

your allowed to run cables in a cavity if they are mechanicallly protected and a fixed to inner skin. ensuring that no bridging occurs. (i think)

Does two layers of brick count as mechanically protected?

RULES IS RULES....

 

[Thomas123]

Does two layers of brick count as mechanically protected?

RULES IS RULES....

not if a rodent was to get into cavity.

I've run cables in cavities before in steel conduit fixed to inner wall.. when the builder builds the inner wall, you then fix your conduit and wire it etc, do what you gotta do. he will then build the outer wall up.

 

[DaveyD]

your allowed to run cables in a cavity if they are mechanicallly protected and a fixed to inner skin. ensuring that no bridging occurs. (i think)

That's interesting, not doubting you, but can you find a ref for that?
Regards
Dave

 

[Thomas123]

That's interesting, not doubting you, but can you find a ref for that?
Regards
Dave

i cant find a reg that states a cable cannot be run in a cavity, its just undesirable. the reason they dont like it is because it wont be supported and may be damaged when pulling cables in, if you use the method i've said it eliminates both of those problems. i cant see how it would not comply.

also bridging is eliminated

 

[topquark]

i cant find a reg that states a cable cannot be run in a cavity, its just undesirable. the reason they dont like it is because it wont be supported and may be damaged when pulling cables in, if you use the method i've said it eliminates both of those problems. i cant see how it would not comply.

also bridging is eliminated

It's not a BS7671 regulation, it's building regs.

 

[Thomas123]

It's not a BS7671 regulation, it's building regs.

Does it state in the building regs that it cannot be run in cavity? I havent got a building regs book, haha

 

[rob121]

Nicked off another forum:
Building Regulations
Building Regulations 2000, Approved Document C, 2004 Edition, Section 5: Walls, paragraph 5.13 b Cavity external walls, requires, amongst other things, that a cavity external wall is at least 50 mm wide, and the cavity is to be bridged only by wall ties or by cavity trays provided to prevent moisture being carried to the inner leaf.
A cavity is intended to provide a gap to prevent water penetration. Cables could bridge this protection if they touch both the inner and outer leaves of a cavity wall. Furthermore, the cables could provide a route for water to drain directly into accessories, with potentially dangerous results.

 

[Thomas123]

Nicked off another forum:
Building Regulations
Building Regulations 2000, Approved Document C, 2004 Edition, Section 5: Walls, paragraph 5.13 b Cavity external walls, requires, amongst other things, that a cavity external wall is at least 50 mm wide, and the cavity is to be bridged only by wall ties or by cavity trays provided to prevent moisture being carried to the inner leaf.
A cavity is intended to provide a gap to prevent water penetration. Cables could bridge this protection if they touch both the inner and outer leaves of a cavity wall. Furthermore, the cables could provide a route for water to drain directly into accessories, with potentially dangerous results.

Cables "could" if installed incorrectly, but if installed like i have stated bridging cannot occur....

 

[Engineer54]

Cables "could" if installed incorrectly, but if installed like i have stated bridging cannot occur....

That must have been wriien by numbties that have spent their working lives sat at a desk, making-up crap like this!!!

 

[Thomas123]

That must have been wriien by numbties that have spent their working lives sat at a desk, making-up crap like this!!!

haha your probably right mate

 

[Kiers1970]

Engineer 54, how true . real world and Reg world have to meet somewhere in the middle, we all know the likelihood of water ingressing through a cable bridging the gap is exrtemely unlikely.
These rules and regs we have to live by, some are laughable, my forend acroos the road couldnt build his extension without stepping it back 1 brick, this apparently prevents a 'terracing affect' so he has a 2 storey extension, built one brick back, lots of extra cost and loss of space. guess what, you cannot see that its set back at all, so what has it achieved? made work for some planners and architects...and builders of course....and I didnt get the wiring job, 'we do it ourselves and our mate part p's it...... good grief.