D
Deleted member 26818
Ahh, Irony, nice.Thats that then. New builds should have all the cables run in the cavity, wouldn't have to worry about sheathing or clipping the cables.
Just a little more subtle than sarcasm.
Just a little more subtle than sarcasm.
D
Deleted member 26818
D
Deleted member 26818
I think the irony is that none of the things she quotes in her song are ironic?
Re drilling through cavity walls. Was just an example. Many Sky installers drill straight through cavity walls. Gas plumbers also.
Cavity wall installers installers drill into the cavity.
As for Reg No., no, I don't know. But correct me if I'm wrong, has not installing cable within external cavities been banned for years?
Don't think it's been banned, but it's definitely not a good thing to do for the reasons given before, ie. bridging the gap, and lack of support for cables (more of a problem with horizontal runs than vertical admitedly). Cavity wall ties also bridge the gap, yes, but they are designed with a drip loop so that the water drops down before meeting the inner leaf of the wall.
Even if it is, it's governed by building regs/good practice which preclude bridging the gap.
Interesting, I wouldn't class an external cavity wall as a void myself. Cables can not be supported in cavity walls. Insulation also cavities.
OK, do electricians still install cables within cavity walls?
I also thought that even PVC/PVC tails between the OMB and consumer unit could not be installed in the cavity. Contractors in my area would use metal sheathing to cover the tails before plastering.
As I have stated in my post #15, the OSG suggests a max length of 5 meters between vertical cables. The BBB doesn't give any actual length.
Is it good practice? That may be down to the electrician.
If doing so then they would have to take any insulation,if installed, into account and size the cable accordingly.
but if they were chased they'd be accessible to repair, in the cavity they aren't
W
Wilko
Hi - I think both can be repaired. I could pull a new cable through a building void pdq if required 
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D
Deleted member 26818
Damn sight quicker than chasing out the old cable, replacing it, filling and decorating.Hi - I think both can be repaired. I could pull a new cable through a building void pdq if required
Yes bricks are porous which is the point of having the cavity.
D
Deleted member 26818
I assume the insulation is, or should be non-porous?
Malcolm
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This thread reminds me, my son is an apprentice plumber on new builds. He asked me what are the regulations for cables in cavity walls?. He asked because the guy he is working with core drilled through the wall for the sink waste in the kitchen he also went through the tails to the cu. (Twice).
When I queried him it turns out if you can imagine looking at the front of the outside of the kitchen, the meter box and cut out are on the left of the kitchen window the tails go into the cavity turns right goes horizontally in the cavity under the window then goes into an internal stud wall and vertically up to the cu. If whoever installed the mains had put it to the right of the window he would not have gone through the tails.
When I queried him it turns out if you can imagine looking at the front of the outside of the kitchen, the meter box and cut out are on the left of the kitchen window the tails go into the cavity turns right goes horizontally in the cavity under the window then goes into an internal stud wall and vertically up to the cu. If whoever installed the mains had put it to the right of the window he would not have gone through the tails.
Cavity wall insulation is not a good thing, imho. Anything that bridges the gap is likely to add to internal damp problems. If the insulation is porous it soaks up water, if it isn't, it can transfer water from the external leaf to the internal leaf. If you have a sealed external leaf, maybe it's ok, but that's uncommon. So many folks have been tricked into CWI by government initiatives where unscrupulouds traders persuade folk, especially the elderly, to let them drill holes in their walls...
I have a flat which was just fine and dandy until the CWI was installed, and the damp and mould were almost instant, albeit it was a very cold and wet winter...
The roof was also a problem, but the water ingress from there simply hit the CWI and travelled into the inner leaf.
Crap! I just had an EPC done on my house which said CWI would cost £500 and save me £27/year over 3 years, and if I installed PV panels at about £8k I could save £327/annum...those are govt figures, as the EPC guy simply downloads them...so, would I spend £8k for that saving? No...I'd turn off some lights.
I have a flat which was just fine and dandy until the CWI was installed, and the damp and mould were almost instant, albeit it was a very cold and wet winter...
The roof was also a problem, but the water ingress from there simply hit the CWI and travelled into the inner leaf.
Crap! I just had an EPC done on my house which said CWI would cost £500 and save me £27/year over 3 years, and if I installed PV panels at about £8k I could save £327/annum...those are govt figures, as the EPC guy simply downloads them...so, would I spend £8k for that saving? No...I'd turn off some lights.
Found from an old IET thread
"Guidance from the Electricity Safety Council says "installing such cables in this way (external cavity walls) is generally an undesirable practice"
The reasons give are
1. Obstructions in a cavity wall, such create a risk of unseen damage during installation.
2. Long unsupported vertical drops may place undue strain on the conductors, leading to damage
3. Polystyrene used for insulation, if it come into contact with thermoplastic (pvc) cable sheathing, plasticiser can migrate from the thermoplastic to the polystyrene
4. Thermal insulation in the cavity may cause cable not to be able to carry the load current without overheating due to their current-carrying capacity being reduced
5. Presence of flora and fauna - unforeseen external influences
There is also a requirement in the Building Regulations 2000, Approved Document C, 2004 Edition, Section 5: Walls, paragraph 5.13 b
and NHBC Standards state that no cables other than electricity meter tails are to be located in the cavity of an external wall"
"Guidance from the Electricity Safety Council says "installing such cables in this way (external cavity walls) is generally an undesirable practice"
The reasons give are
1. Obstructions in a cavity wall, such create a risk of unseen damage during installation.
2. Long unsupported vertical drops may place undue strain on the conductors, leading to damage
3. Polystyrene used for insulation, if it come into contact with thermoplastic (pvc) cable sheathing, plasticiser can migrate from the thermoplastic to the polystyrene
4. Thermal insulation in the cavity may cause cable not to be able to carry the load current without overheating due to their current-carrying capacity being reduced
5. Presence of flora and fauna - unforeseen external influences
There is also a requirement in the Building Regulations 2000, Approved Document C, 2004 Edition, Section 5: Walls, paragraph 5.13 b
and NHBC Standards state that no cables other than electricity meter tails are to be located in the cavity of an external wall"
diyterry
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The house I'am doing up has cables running up and down in the cavity.
Not ideal at all. If house is having work done then now is the time to get cables routed correctly.
diyterry
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I've got the floor up in the bathroom and I can see the cables for the RFC ( hope I've got that right ) and cooker disappearing through the wall into the cavity.
diyterry
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No the consumer unit is on the same wall about three yards in the opposite direction. There's a double socket in the kitchen, below where the cables disappeared into the cavity. The cookers further along on the same wall.
It could be the way the cables have been routed into your CU, i.e. via the cavity. There's probably thousands of properties wired in this way in the past. As others have said, not against any regs etc, just not good practise in my & others opinion. But I suspect its been like this for some time, to no avail. You would need to employ a competent electrician and seek he/she's opinion.
diyterry
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Before we bought the house we had the wiring surveyed by an electrician and he couldn't find any major problems.
T
Toneyz
OK, then no problem.
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