Cable access through insulated cavity wall. Possible?

If the cable is totally surrounded by isulation for more than 5cm then it will need to be derated. What is it your trying to do/achieve? What sort of shower?

 

Only tails can be run in cavities. . .anyone else want to clarify this?

 

Your reg. spark will probably end up running the cable under the floor and using a landing airing cupboard as the communication point.

You should not be doing this mate, its a new circuit and warrants Electrical installation cert as well as notification to BC

Don't say you have not been informed

 

Good luck with that!

 

Insulated cavity? I am assuming not the external wall cavity? A stud wall or boxed in soil pipe? It can be done, but the cable needs to be sized to take into consideration the down rating due to insulation.

 

Do you mean 6mm to 10mm?

Why are you thinking of upgrading the shower to a bigger power one?

 

You cannot run cables in wall cavitys only tails is my understamding (anyone got a reg on this?)

This electrician you are using must be daft, your using his licence number to install cabling where it is not allowed??

I think your doing it all yourself and telling us what we want to hear regarding the test aspect

leave it alone is my advice

 

You should be grateful a pro like Si-Fi has taken the time to help you out. He doesn't get paid for it and is TRYING to help you, not criticize.

 

Asked this question to my Scheme provider years ago as I wire a lot of conservatories where sometimes the only place to run the cables is within the dwarf wall cavities. I like to think that as I can see what is in the cavity I can comply with all of the regulations quoted. Still have to run some cables where I shouldn’t but hey ho sometimes all we can do is what we can do and thank god for Rcd’s

There is no direct regulations saying you can’t but

The NICEIC suggests it is difficult for installer to ensure compliance on all of the following areas inside a cavity that you can’t see into.
522.8.1: Damage to cables during installation
Obstructions in cavity e.g. metal wall ties, mortar projections, create a risk of unseen damage.
522.8.4: Strain on cables lacking support.
Long unsupported vertical drops may put strain on conductors.
522.5.3: Materials liable to cause mutual or individual deterioration.
Expanded polystyrene sheets, granules or foam used in buildings for insulation if comes into contact with thermoplastic (pvc) cable sheathing, plasticiser can migrate from the thermoplastic to the polystyrene.
523.7: Cables in thermal insulationThermal insulation installed in cavity walls during or after construction, the cable current-carrying capacity is to be taken as half the �clipped direct� (Reference Method C) rating unless more precise information is available.
522.9.1 and 522.10.1: Presence of flora and fauna
Designers and installers may not necessarily detect or predict the presence of flora or fauna in a cavity wall. The wiring system should be selected to withstand all the external influences expected, or damage to cables may occur from, for example, mould or rodents.

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.

NHBC Requirements
It is noteworthy that the National House-Building Council states, in Section 8.1 - S2 of NHBC Standards, that no cables other than electricity meter tails are to be located in the cavity of an external wall. Where meter tails do have to pass through the cavity, however, this does not preclude the requirements of BS 7671 referred to in this topic having to be met.

 

If I go across a cavity I use swa or a bit of placky conduit. I've never found a need to run cable "up" or "down" a cavity though have been tempted.

 

Its nice to know Part P is still doing its job when anyone now can run in a cable and powers up 50% of the current demand sat in the REC's carrier. .

You have a way forward but its not how we can do it to comply with regulations and safety standards

All the best and no criticisms intended, I am helping you do the job correctly