Conduit to allow for rewiring

[padstar]

I am going to be getting my house rewired as part of a larger refurbishment project. The rewire itself will be carried out by certified electrician but i am currently undertaking some minor builders works myself in preparation. Most of the existing sockets and switches will be removed and relocated in the new design. The floors will be up at the time of rewire.

To give the spark as straightforward job as possible and so that they are used for electrical work rather than prep work, i plan to install the back boxes and do the chasing myself (removing the existing as i go) then get the plasterer in prior to the spark doing their thing.

My thinking is that if all back boxes have conduit runs connected to them running to the floor/ceiling void all cabling should be able to be pulled with relative ease. Is this a reasonable assumption to make or will the spark want to kill me when they see it?

Assuming it is a reasonable way to do it what is the best conduit system to use? Should it be rigid or flexible? Plastic or metal?

Any advice would be much appreciated.

 

[Risteard]

Get the spark involved first. If it was done to me I'd rip the whole lot out again or more likely decline the job.

 

[Celeronmanuk]

I've done this kind of thing three times now, every time the electricians were more than happy not to do the chasing and the making good. Just discuss it beforehand with whoever you would like to use to actually cable it up and test and make sure there are happy.

Also the electricians were willing to let me labour for them on the days and help pull cables. It worked well as I already knew where everything was going and the best routes.

For conduit I've used 20mm round with the backbox connectors, or oval depending on how deep the chase was going to be and cable number/size.

I don't understand the above comment of potentially ripping out perfectly good backboxes and conduit, why would you do this??

 

[SUNRAY]

I am going to be getting my house rewired as part of a larger refurbishment project. The rewire itself will be carried out by certified electrician but i am currently undertaking some minor builders works myself in preparation. Most of the existing sockets and switches will be removed and relocated in the new design. The floors will be up at the time of rewire.

To give the spark as straightforward job as possible and so that they are used for electrical work rather than prep work, i plan to install the back boxes and do the chasing myself (removing the existing as i go) then get the plasterer in prior to the spark doing their thing.

My thinking is that if all back boxes have conduit runs connected to them running to the floor/ceiling void all cabling should be able to be pulled with relative ease. Is this a reasonable assumption to make or will the spark want to kill me when they see it?

Assuming it is a reasonable way to do it what is the best conduit system to use? Should it be rigid or flexible? Plastic or metal?

Any advice would be much appreciated.

 

[SUNRAY]

In my experience of working within the trade for 40+ years, electricians will see the empty tube in the loft or floor void and go ''HAPPY DAYS'' I will suggest that you run two 20mm or one 25mm conduit for ring circuits as getting 2x2.5mm T&E into a 20mm tube from an awkward space is tricky. The same is true for more than 2x lighting cables.

I'd second speaking to your spark before you start, mainly to double check his cable routes and quantities of cables, he may have different ideas to you.

 

[johnny2007]

Yes, speak to the electrician.
When we rewired our house we found the system to be completely piped.
The electrician was well happy to use the existing metal pipes 25mm.
He was in and out in 2 days instead of the anticipated 4 days and gave us a £150 discount as he only had to chase 4 extra sockets instead of the whole lot.
Some electrician may not be happy, so speak to him first.

 

[padstar]

Thanks for your advise. Cant see any reason a spark wouldn't be happy with empty tube there for them. Its then far quicker to pull the cables and get out of there.

Do you recommend metal or plastic tube?

 

[johnny2007]

Ask your spark

 

[Celeronmanuk]

Do you recommend metal or plastic tube?

I'd use 20mm round in plastic as it's cheap. You'll be limited by the knockouts using 25mm. I can't see any reason to use metal.

I did my ring circuits with 2 x 20mm round and lights with oval. Also did cat5e and coax with 20mm round.

New work is generally all done with capping, so anything in conduit is going to be "better" than that.

I did all the joist drilling too cos I'm fussy. Electrician was quite happy to not do any of this work.

 

[Risteard]

Its then far quicker to pull the cables and get out of there.

It really isn't. Trying to get twin and skins down a conduit already fixed in place isn't much fun a lot of the time. After all conduit it designed for singles.

 

[Celeronmanuk]

It really isn't. Trying to get twin and skins down a conduit already fixed in place isn't much fun a lot of the time. After all conduit it designed for singles.

Eh? Pulling a few meters of 2.5 t&e down 20mm round conduit is ridiculously easy!

 

[Risteard]

Eh? Pulling a few meters of 2.5 t&e down 20mm round conduit is ridiculously easy!

Not when it's 2 * 2.5mm^2 which it invariably is.

 

[Celeronmanuk]

Not when it's 2 * 2.5mm^2 which it invariably is.

True, not as easy, but still goes with space to spare. I put in 2 x 20mm conduit to each socket in my house, overkill really, but made cabling simple.

 

[john4703]

It really isn't. Trying to get twin and skins down a conduit already fixed in place isn't much fun a lot of the time. After all conduit it designed for singles.

Why would you use T&E in conduit, would singles not be easier, cheaper and better? It means all the run needs to be in conduit but why not so it all in conduit?

 

[Celeronmanuk]

Why would you use T&E in conduit, would singles not be easier, cheaper and better? It means all the run needs to be in conduit but why not so it all in conduit?

Because the OP is only running conduit for the drops so he can do the chases and make good beforehand. Through the floor/ceiling space it's not going to be in conduit I don't imagine.