Best way to wire a house with new concrete floors

[Krane]

The lower floor of my house ( 3 rooms and a hall ) is being concreted to avoid future flood damage.
I have spoken to a few electricians but to date none has any experience of laying a conduit cable guide in a concrete floor.
Reading the various Threads. Putting cables in a plumbers polythene pipe is acceptable but may prove challenging when you need to rewire. If it is layed on the DPM before the concrete is poured it can be dislodged.Laying plastic conduit on top of the concrete base before the insulation goes in would be easier to fit but presumably reduces cooling. The other method of laying the cables in a rectangular plastic conduit with a wooden lid( Manthorpe Building products ) near the surface of the finishing screed around the perimeter of the rooms is rarely discussed. It has the advantage that you can get at it even if it has a covering of screed over it.

Does anyone have any recommendation on which method I should use. I will only get one shot at it.

You knowledge and experience would be greatly appreciated.

Krane

 

[davesparks]

The traditional methods of wiring in solid concrete floors are steel conduit or MICC which is installed prior to the concrete being poured.

If it is only the ground floor which is concrete why not just wire it from above as usual?

 

[trev]

I think I'd wire through the ceiling/floor void and drop to any accessories.
Edit
Dave beat me to it

 

[Octopus]

I think the ceiling and part m should be considered here!

 

[Des 56]

If you were to wire through a conduit system (in the concrete or over the concrete) its likely there will be ingress of water and a shot wiring system next time it gets flooded (unless its well water tight and the flood is lower than the accessories)

Like the others have said drop down.even a conduit system would be better dropping down if its for ease of re wiring

 

[ifindoubtdont]

There are some holiday homes in Borth, Mid Wales that regularly have the winter storms come through the downstairs of the properties, all cabling is now from ceiling down and socket heights are above the tide line, concrete/stone floors have been put in to save damage and all furniture n stuff is moved to the next floor up for the winter. If it is likely you will get flooded again then give ceiling down some serious thought.

 

[Spoon]

I watched a program many years ago where they redesigned it because it flooded on a regular basis.
All electrical sockets where wired from the ceiling down. No cables where in the floor.
The concrete floor sloped very gradually to a drainage point.
They even had fold out brackets in the wall, so you can put the settee and stuff on them whenit flooded.

 

[Pete999]

Heavy gauge PVC conduit, all joints glued, draw wires installed PRIOR to concreting, PVC conduit fixed where possible to building fabric, jobs a goodun

 

[driverman]

As suggested, wire from above ceiling. Years ago I wired many blocks of flats using Hi -Tuf cables laid directly on slab then the screed pored directly onto them. Was a swine to install / strip the cables in cold weather though.

 

[Krane]

Hi
Thanks for all the advice.
In answer to the question why not drop it down from the upper floor the answer is that I would like to minimise the disruption to the house. At the moment the floor is being removed and I have access to put conduit in.
I have spoken to the building regs guys and the electrical guy indicated that if I used plastic conduit buried in the sand before the DPM and concrete are put in It will be Ok. As one of the posts suggested clipping it to the wall will protect it during the concrete pouring.
It is only one ring main and the supply to the kitchen which is very close to the fuse box.
I was planning a 25mm diameter conduit so lots of room to dissipate heat if there is any.
So in summary I agree dropping down is the best solution but given a desire to minimise decoration rework buried conduit above the hard ore in the sand with glued joints. Any idea if the cable has to be derated or is the lower ground temperature and 25mm conduit enough?
I appreciate your help.

Krane

 

[Spoon]

Hi Krane,

If you are putting any size conduit in the floor and your house floods again, how are you going to get the flood water out of the conduit once the flood subsides? I don't know how well you can seal these things...

 

[Krane]

The plan is to make a shuttered pit where the services come into the house and where the fuse box is located on the wall. The conduit will come into this pit horizontally and level and it will enable all the risers to drain into it.
The key is not to make any sealed Us.
On the other hand ……..does it really matter if there is some water around the cable …….it is sealed and it will help the conduction…...

Krane

 

[Spoon]

The reason why I ask is that flood water, as you know, is not nice clean water. Its full of s$$t, oil and lots of other things. Do you really want that in open conduit stinking out your house.
As to cable being in water: All depends on the cable being used.

 

[Krane]

Thats a good point!

If I seal the risers with silicone rubber that will prevent it getting in. I also have the option of flushing it back into the pit under pressure to get rid of any nasties.

Krane

 

[Spoon]

This is the think Krane, I work in Industrial where we use correct IP rated glands and correct cable. Don't know how well sticking some silicone rubber into the conduit would stop water ingress. Last thing you want is to do that, water gets in anyhow then you have to remove the silicone to get rid of the water.
There are people on here that would know the solution better than me.
I would personally bite the bullet and get all the cables to come from the ceiling down. If a jobs worth doing its worth doing properly.

 

[Krane]

I can't argue with that wisdom!

Thanks for your help

Krane