Running Cable under floor with UFH?

[A032701]

hello all,
seeking some advice on how to run cables underfloor with ufh as well.
i am quoting for a complete house rewire as they are doing some substantial works and the electrics are in poor condition
the floors consist of hardcore then sand then dpm sheeting, celotex on top of that with wet under floor heating clipped to the celotex, with the screed on top. i want to run my cables to the sockets under the floor so to save time. i could put them on the celotex with the ufh but obviously there will be major heat temperatures to work with. what would be the best way of overcoming this?
thanks in advance

 

[farmerspark]

If you must, run 25mm conduit under the insulation with your cables in. I've done it before with 20mm but it's a pain in the proverbial, getting 2x2.5mm through swept elbows and tees up to socket boxes.

 

[A032701]

would you put it under the DPM matting and create a mini trench in the sand for it to be seated in?

 

[farmerspark]

I imagine whoever is doing the DPM wouldn't thank you for that. Trying to maintain the damp seal around vertical conduit would be a pig of a job. Be better on top of DPM then they could drop a layer of 25mm celotex in around your conduit, then top up to the required thickness in a single sheet

 

[Midwest]

Thats an unusual floor design, the sand bit?

 

[Baddegg]

Thats an unusual floor design, the sand bit?

Hardcore blinding with sand is the norm...

 

[Midwest]

I'm used to suspended concrete block or concrete screed?

 

[Baddegg]

I'm used to suspended concrete block or concrete screed?

Sand is about 2oo mm ish below the screed mid....

 

[Midwest]

Sand is about 2oo mm ish below the screed mid....

Type 1 surely?

 

[123]

Would it not be quicker to run cables through ceiling void and drop down to sockets, rather than a large amount of time installing conduit and drawing cables through it?

 

[Baddegg]

Type 1 surely?

50 mm screed over 100mm concrete over 100 mm jablite over 1200g dpm over sand blinding over hardcore/type 1 ish.....

 

[Barnaby Stedman]

I would say from my experience that running 2 2.5mm's through 20mm conduit is very difficult - especially when it gets to bends etc although its alright running it along the straight.

 

[Andy78]

I'd be exhausting every other opportunity before running cables in a floor with ufh.

 

[magnoliafan89]

Id only do this if running to an island in a kitchen. Or if you didnt wanna chase walls i suppose

 

[Barnaby Stedman]

Id only do this if running to an island in a kitchen. Or if you didnt wanna chase walls i suppose

On that one, what really is the easiest way to chase? some people use dedicated chasers, some use an sds with a chisel bit (including myself) etc but what way is the fastest?

 

[Baddegg]

Wall chaser with decent dust extractor and sds with scrutch chisel...

 

[A032701]

the only problem is that i am installing some floor boxes and the insulation has been put down already
could i put 4mm down so the heat has less impact on the cable? or would heat resistant cable do the same job

 

[Baddegg]

You’d have to redo your cable calcs with the right cf.....heat resistant cable is resistant to outside influences not the load on the cable cores..

 

[Midwest]

50 mm screed over 100mm concrete over 100 mm jablite over 1200g dpm over sand blinding over hardcore/type 1 ish.....

So no just sand then, like beach stuff.

 

[123]

On that one, what really is the easiest way to chase? some people use dedicated chasers, some use an sds with a chisel bit (including myself) etc but what way is the fastest?

Getting someone else to do it.