Cables run in Cavity Walls

[Engineer54]

condensation forms in the inside of the outer leaf, this will then drip down to the bottom, if there's something bridging the cavity then it will move across to the inner leaf. also driving rain can penetrate small cracks in the render or pointing, which will cause the outer leaf to get wet and again moisture will drip down the inside of the cavity and if it comes across something bridging the cavity then it will move across. now in an ideal world the outer leaf would be completely watertight, but over time problems can develop with guttering, fascias, pointing, flashings, render etc, and in those cases water gets in, now if the cavity is clear then it will just drip down to the bottom where it will do no harm, but if it can get across the cavity then it will and start soaking the inner leaf.
Ive seen things bridging the cavity enough times to know what i'm talking about, no amount of people on a forum telling me it's an old wives tale or to "get real lol" is going to change my mind. if you think you can just do anything you like to a cavity and then if you end up with damp problems then it'll be down to the outer leaf letting water in and in no way related to whatever there is now bridging the cavity( be it insulation, cables, pipes etc) then you need to ask yourself why cavity walls were invented in the first place, and had the "thing" bridging the cavity been there then would damp be able to get accross?
im not saying anything crossing a cavity will cause damp, if i have to drill through a cavity then I drill from the outside at an upwards angle (about 30 degrees) that way if any moisture were to get on the cable then it would just drip off as it can't travel uphill.

We'll agree to differ then, because i am Adamant in what i have posted too!! By the way, there shouldn't be any condensation within the cavity area, ...if there is then something else is wrong, and it's nothing to do with any bridging being present.

One more thing, i don't think i've ever seen a cavity between the two courses of bricks/blocks being completely clear/clean, or should i say, that haven't numerous counts of fallen mortar trapped by ties etc, bridging the cavity. No sign of damp on the inner walls anywhere..

 

[rich.250]

Tbf where I've seen it first hand the outside block wall was absolutely soaking!!!

 

[Ponty Massive]

This reminds me of the argument of running cables in the cavity of a conservatory wall.......

 

[SPARTYKUS]

Has anyone mentioned 120 year old miners cottages with metre thick walls?

No cavity here!!!

Maybe should have stuck with them what withh all the arguements cavity walls are causing!!!

 

[Rockingit]

Has anyone mentioned 120 year old miners cottages with metre thick walls?

No cavity here!!!

Maybe should have stuck with them what withh all the arguements cavity walls are causing!!!

I used to live (a long time ago) in a GradeII C13th (parts > Victorian) old hostelry / pub. One of the INTERNAL walls was 18' (and it was just wall, no hidy holes) and the exterior walls were built castle style - thick outer, thick inner and the 'cavity' filled with rocks and rubble. Over the centuries it had sunk about 1m into the ground, no dpc there!!!

 

[thekingiam]

Considering what you could have done this, I would say, is not a problem, if you can avoid it then yes do not run cables in the cavity, but also be realistic about installation.
Just don't use it for your assessment!:angel_smile:

i am thats what concerns me!

 

[thekingiam]

should i just admit this before hand and say the job was a nightmare,should i put it on eic as another problem that could be addressed?
the property is my sisters so i could always correct at a later date if elecsa had a problem with it.
i got to admit this property was never the ideal property i wanted to use as for registration but the only one i had the opertunity to use.i did a partial rewire as not to chase walls to lighting switches but connect above either via light fixings or mf boxes. didn't expect to have to put in tt spike as never done it before,never expected kitche lights and sockets to be fed under lintel in kitchen extention touching plasterboard ceiling.

 

[thekingiam]

i have got to admit though if i needed a learning experiance to do domestics this was the house!

 

[richy3333]

If this is your job for assessment then I think you are panicking waaaaaaay tooooo much. If you are going for a DI, the assessor is going to slap the sticker on your back. The scheme want your money. I really don't think the assessor will pay that much attention mate. You could put on the certificate that its wired through peanut husk and I doubt the assessor will notice (installation method R118 by the way). You just need to show a tidy job, an ounce of intelligence, a stash of cash and convince him that you won't kill yourself or the customwer. And then 'Jobs-a-good-n'

 

[dagrat]

Has anyone mentioned 120 year old miners cottages with metre thick walls?


No cavity here!!!


Maybe should have stuck with them what withh all the arguements cavity walls are causing!!!

The reason these walls were so good was due to the porosity and continual cycle of absorption and evaporation coupled with the width. Most cavity walls with a cavity wall not only depend on the level of absorption of the brickwork but also the level of workmanship.
Cavity walls are so designed that even if the outer leaf was saturated, the inner leaf should remain dry. This is achieved by drip features on wall ties and a separation between leafs preventing capillary action of water.
If a wall is correctly constructed then I personally, would suggest that the mere fact of a cable touching both leaves could not lead to damp, as the cable is not porous, however if the pointing is poor then there is a chance of running water down the inner face of the outer leaf, which could run across to the inner leaf and cause damp.


Interstitial condensation is a very real damp causing problem particularly in walls in new timber houses with no vapour barrier, but thats another issue.

 

[Elmer BeFuddled]

I used to live (a long time ago) in a GradeII C13th (parts > Victorian) old hostelry / pub...

SWMBO tells me I spend too much time in my local as well!

 

[D E P Northeast]

no no no way should you do this i saw some one lose there niceic for this

 

[Knobhead]

Was it painful?

How did the assessor know the cable was run in the cavity?

 

[SPARTYKUS]

Maybe he had advanced Xray scanning equipment aka a sledgehammer (persuader also sometimes called)

Maybe it was his last day!

 

[Conan Bujwid]

Only ever seen it a few times not advisable

 

[dagrat]

Was it painful?

How did the assessor know the cable was run in the cavity?

I think checking your cavity is a new initiation method that the niceic are running now........
I beleive in being thorough but this is going too far!

 

[Engineer54]

no no no way should you do this i saw some one lose there niceic for this

I find that holy unlikely, ....the NICEIC give up one of it's annual cash cows, ....NEVER!! lol!!

 

[Farmelectrics]

When I've done conservatries in the past there was no other route than the cavity to run your cables to sockets

 

[Dan]

Just bumping some threads in the Electrical Wiring Theories and Regulations forum category here on our Electricians Forums. If this specific topic isn't current, just ignore it, it'll drop off the list in no time. However, if it's something you'd like to contribute to, feel free to reply and bring it back into current discussion.