Cable to island in insulated floor

[Hefferl]

I need to install a cable for an induction hob in a kitchen island.

Hob is 7.2kw.

Floor will be screed on 100mm insulation on concrete.

I'm intending to use 10mm T & E in conduit within the insulation.

I see this as ref method A and good for 44A (table 4D5).

I'm considering using something like 65mm square line downpipe with a 90 bend at each end to pop up under island and another unit at edge of room, thinking this would be easy to construct, self supporting, easy to insulate around and give good amount of air around the cable.

What do you think? 

 

[Manator]

I have done similar but used 43mm waste pipe as the ducting, its readily available and easy to construct. The proper way to do it is to install a cable channel, in the good old days construction used to be about everyone. Sadly now each trade fends for themselves, I have not seen a shuttering joiner on any site for years.

 

[Blue Duck]

I have done similar but used 43mm waste pipe as the ducting, its readily available and easy to construct. The proper way to do it is to install a cable channel, in the good old days construction used to be about everyone. Sadly now each trade fends for themselves, I have not seen a shuttering joiner on any site for years.

Dont tell the lecktric polis, They'll have you in court for.... um err... I dunno. :C

We have a joiner that does a lot of shuttering.

 

[Adrian]

How about using SWA and and screed it in 

 

[Lusk]

6mm2 singles in 20 or 25 mil pvc tubing, with swept bends, for me.

 

[Manator]

How about using SWA and and screed it in 

6mm2 singles in 20 or 25 mil pvc tubing, with swept bends, for me.

Both are viable solutions, however in domestic situations we have the problem of how do we continue the cable? With SWA and singles we have the problem of terminating them to continue the run.

Properly designed buildings use cable runs, this is where the shutter joiner comes in handy. He would lay the routes above the insulation within the concrete before screeding. The electricians would then lay conduit runs in either plastic or metal and the plumbers would run their pipes for wastes or water pipes., job done all would be screeded over.

Bring back the good old days I say.

 

[Rob_the_rich]

I agree with method A, but am thinking possibly 100#, or even 101# if you include the screed and possible underfloor heating??

Don't know depth of screed but guessing 75mm, so would be wary of running any conduit in it if over insulation, it might crack.

I would put the conduit direct on the concrete and insulate over it, to allow the heat to dissipate through the cooler concrete slab

I would also be wary of using rainwater pipe, the joints are spigot to socket and are not air-tight, thinking of deplasticiser vapours given off by expanded polystyrene, although this might be ok with modern materials, not sure. Best to go with 1-1/4" waste pipe with swept bends, glued.

 

[ProDave]

Funny enough I first fixed the under floor cables for an Island today, before the joiners put the floor down.

But in my case it's a timber floor so my conduit is on top of the insulation immediately under the floor boards.

 

[Rob_the_rich]

or use a boat.

 

[Rob_the_rich]

.....

I would also be wary of using rainwater pipe, the joints are spigot to socket and are not air-tight, thinking of deplasticiser vapours given off by expanded polystyrene, although this might be ok with modern materials, not sure. Best to go with 1-1/4" waste pipe with swept bends, glued.

This is rubbish, plasticiser migration occurs through contact between cable sheath and expanded polystyrene, so rainwater pipe ok. ooops

 

[Sidewinder]

This is rubbish, plasticiser migration occurs through contact between cable sheath and expanded polystyrene, so rainwater pipe ok. ooops

Quite Rob!

Rainwater pipe, 32/43mm waste & pvc electrical conduit are all the same grade pvc, so we'd have terrible issues with pvc cables in pvc conduit if that were the case.

Blame it on a brain fart.

 

[Evans Electric]

I'd have gone with 6mm T/E  and 25mm PVC conduit ....in fact I have ....many  times.