Mains power point wiring, and associated cable cladding/tubing

[OwlHoot]

I am concreting the floor of a large room, but will also need to have power points fitted round the edge of this room.

Apparently the standard technique is to lay plastic tubes round the edge of the room before the concreting so the power cables can later be pushed through these.

I'll probably hire a professional electrician to do the actual wiring; but as I am doing the concreting myself, I'd like to lay these tubes beforehand.

(for speed-readers here come the actual questions ..)

To buy these tubes, what should I be web-searching for, i.e. their name and perhaps brand if any particular brand is notably better than others?

Also, if I buy the cables what, um, Ampage should they be? (I don't mind spending a bit more for a margin of safety, e.g. 100 Amps if only 50 Amps is needed.)

Many TIA

[Archangel]

The "tube" is called conduit.

2.5mm sq cable will cover as many sockets as you can fit in an area < 100m sq if wired in a ring. 4mm sq cable would serve a large radial circuit but is difficult to work with and you would be unpopular with an electrician.

The usual way to wire a room with a concrete floor is not to run the cables in conduit, but to run the cables down the walls in protective sleeves from the ceiling void. Cables can be run horizontally between sockets either clipped direct to the walls or buried in the walls in protective sleeves.

If you are using floor sockets please ignore the previous paragraph.

If you use a professional electrician he is unlikely to be happy using cable you have laid as it is his name on the certificate.

If you are not in the eu then all bets are off.

[northernladuk]

Get an electrician to do it. It's not gonna cost much and getting it wrong will be a very expensive mistake. The pennies you save just isn't worth the risk.

[OwlHoot]

Many thanks for the prompt replies guys.

I spent quite a while searching for conduits, but there is such a bewildering variety, and not all in the UK, I'm unsure what to buy, especially as some may not meet the right UK standards, if they are not intended for mains cables for example or only for lower US voltages.

So assuming I go with 4mm cables, despite possibly upsetting the electrician, can you suggest a specific conduit manufacturer and model, either metal or plastic?

A link to a UK supplier would be great.

Not bothered about the price, as I imagine they aren't very expensive anyway.

TIA

[WTFH]

Prysmian 6242Y Twin & Earth Cable 2.5mm² x 50m Grey | Cable | Screwfix.com
Tower Conduit Heavy Gauge 20mm x 2m White (40m) Pack of 20 | Plastic Conduit & Acc | Screwfix.com


Not the cheapest, nor the best, but does the job.

[WTFH]

The other thing is that cable sold by Homebase had to be recalled coz it was made in China.

Make what you will of that.

faulty, non compliant cable

Screwfix are owned by B&Q, so might be worth checking out the quality of their stuff too.

[Contreras]

Prysmian 6242Y Twin & Earth Cable 2.5mm² x 50m Grey | Cable | Screwfix.com
Tower Conduit Heavy Gauge 20mm x 2m White (40m) Pack of 20 | Plastic Conduit & Acc | Screwfix.com


Not the cheapest, nor the best, but does the job.

+1 for Screwfix, efficient click-n-collect if you have a local trade counter. Some of their kit is bargain basement but it's the same stuff that you'd pay full retail at a B&Q or Homebase.

Go with the cable size your electrician recommends 2.5mm is easier to work with though, IMHO it would be better to run multiple rings on separate mcbs rather than resort to 4mm.

Your electrician is going to need these too:
Cable & Flex Draw Tape | Cable Access | Screwfix.com
Plastic Conduit & Acc | Electrical Conduit | Screwfix.com

[Fandango]

Toolstation is cheaper than SF and free next day delivery over £10
Twin & Earth Cable (6242Y) Grey 2.5mm2 x 50m -

A word of caution you are never going to be able to push T&E cable around and sort of corner through conduit, unless you can find some large sweeping radius'

what'd you'd spend on conduit you'd be better chasing the runs required out of the wall and paying a plasterer £140/day to re skim over it once its done

[Archangel]

The cables linked to in previous posts are not suitable for running through 20mm conduit. Cable running through conduit does not need the outer sheath. If you run double sheathed cable through conduit you need to derate the current carrying capacity.

The cable is usually called "singles" and is just the conductor and a single sheath. So you would run 3 cables per run, a live (brown), a neutral (blue) and an earth (green/yellow). The earth would not need to be 2.5mm, 1.5mm would suffice.

Cable | Cable & Cable Management | Screwfix.com

[northernladuk]

And therein is the reason you get an electrician in...