Running cables in the floor screed.

[EddyP]

As part of my extension, there is a conservatory going onto the back of the house. On one of the walls in the conservatory i'd like a couple of sockets potentially for a TV in the future.
As there is no roof void, and due to the door/wall layout, the only option to get cables there would be to run them in a conduit in the floor screed.
Would this be ok, if i use a steel conduit, and then earth it?
I'm assuming the norm would be a 25mm steel conduit? If so what's the normal method for earthing it? use clamp similar to those used for earth bonding on pipework?

Thanks

 

[BS3036]

If you could get it deep enough you could use plastic conduit. You'd probably want to go for 75mm screed though. If you are putting in wet underfloor heating then you have the additional depth of 75mm insulation below the screed to bury the conduit in.

Maybe another conduit for an aerial, or whatever else you think of, though?

 

[plugwash]

steel conduit is fine, the normal way to earth it is to thread the end and then use a proper conduit entry adaptor to join the conduit to the box.

 

[EddyP]

There is 75mm of insulation, and 75mm of screed going down, so there is the potential to put it 150mm below the floor surface, if I wish to.
In total I was planning 4 conduits, two for heating pipes, one for aerial, and one for power.
I assumed due to the 17th regs though that it would have to be earthed conduit, but thinking about it as BS3036 has said, if i can put it deep enough, it would be ok to use plastic. In which case id rather use flexible plastic, and then bring it to the surface right next to the wall so the cables can then go up behind the plasterboard vertically as normal.

Thanks