Cables in cavity - wall being built

[bernardgreen]

The cavity and the conduits in there will be cold.

Any water vapour in the conduit will condense into water in the conduit. This will draw in more water vapour through the sockets and other items the conduit connects. This water will accumulate until it over flows into the back of one or more of the sockets.

How fast this happens will depend on temperature and how much water vapour there is in the room.

One lamp fitting in a similar but extreme case produced about 1/4 pint of water per week until a vapour barrier was installed at the far end of the conduit

 

[ericmark]

If your really that worried about exposed cables then the methods used in listed building could be used. Taking out a little mortar and using mineral insulated cables will clearly hid all cables. However be seated where you look at the cost of using mineral insulated cables.

To look neat it is better to take cables to ceiling hight and drop for each socket using trunking at ceiling height (even if no ceiling) looks neat. As for the drops if you want them a little neater then ali-tube cable can be dressed very like mineral insulated and would look better than twin and earth or trunking.

But again we hit the cost. Ali-tube tends to be sold by the role not length although I have seen it by the length on the internet. There are other methods to help. In a warehouse for food they wanted walls as clear as possible so easier to clean. It also was a large area and the sockets were for cleaning equipment only. So a ring was laid in the roof space with a junction box where every socket was required and a spur fed each socket. As a result just one single mineral insulated to each socket today likely would be ali-tube.

Point is there are many ways to wire without using cavity. When you say garage there are two very different types. One is used to store a car and maybe from time to time we may use the space for other things. The other is a repair place for cars and trucks. The latter clearly needs cables protecting better than the former. With the latter metal conduit, SWA and mineral insulated is order of the day with former normally simple twin and earth.

I see the protection offered with cables in the cavity but to be frank walls are not that strong and if there is an accident then being able to see the cables rather then for them to be in the rubble is likely a better option.

I remember some daft Dutchman dismantling a spring brake without the clamps the result was a hole in the wall where the parts hit it. Lucky the Dutchman only suffered instant dismissal and was not injured. But if the cables had been in the wall then it would have been a really big job to repair.