Conduits

[drdes]

I have bought some speaker cables (QED silver anniversary) and will shortly be getting an electrician to instal them (chase them up a wall, though the ceiling and out the other side).

I would like to put the wires in a conduit - can someone recommend which conduit to use (are there any specific things I should be looking for?).

Also, just to understand, will I be using one conduit per speaker (in the example of the rear speakers) that will go up the wall, then turn 90 degrees across the ceiling and then turn 90degrees again at the back wall - or would I have a separate conduit where the wire turns?

 

[Magslad]

I have bought some speaker cables (QED silver anniversary) and will shortly be getting an electrician to instal them (chase them up a wall, though the ceiling and out the other side).

I would like to put the wires in a conduit - can someone recommend which conduit to use (are there any specific things I should be looking for?).

Also, just to understand, will I be using one conduit per speaker (in the example of the rear speakers) that will go up the wall, then turn 90 degrees across the ceiling and then turn 90degrees again at the back wall - or would I have a separate conduit where the wire turns?

You say that you have an electrician installing the cables - any half-way decent sparky will bring and use conduit if he's chasing the walls and installing cables. If it's all being hidden then I would imagine he'd use standard PVC channel like this.

I'm not sure I understand your questions about 'one conduit per speaker' though?

 

[drdes]

I guess what i am asking is are coduits flexible so that you can bend them round corners?

 

[Paddy!]

Bendable?

I would expect PVC conduit to be cut and mitred to go around corners.

 

[Magslad]

I guess what i am asking is are coduits flexible so that you can bend them round corners?

If you are hiding all the cables in the wall then you don't need to bend the conduit round a corner you just run it up to the corner (it's only to protect the cable and provide a stable surface to bond to for the plaster). If you are running cables above the ceiling then you wouldn't need this part to be in conduit anyway, just where you are chasing the walls.

If you are running the cable on the surface of the wall and covering it with trunking, then depending on what type you buy you can either get corner pieces or as Paddy says you would just mitre it for any corners.

 

[Sonic67]

I guess what i am asking is are coduits flexible so that you can bend them round corners?

It can be bent. You put a spring down it, warm up the plastic and then bend it around your knee. The plastic bends around the spring and keeps its shape. Metal conduit is bent on a bending machine. As above though I would have thought he'd use metal or PVC sheathing/channelling unless you need conduit specifically. Usually conduit means a lot of chasing out of brickwork if you want it below the level of the plaster.

Usually the cable goes into the area between the floors, is fed through the joists, and then comes down again in channelling. You can't run speaker cable through the same conduit/channelling as mains cables or the same holes in joists.

 

[drdes]

i hadnt though about the conduit being used to put the plaster on! although it does make sense

I was thinking more along the lines of, if at any point I want to replace the speaker wire (without going behing the ceiling or removing floorboards), would it make sense to have a conduit across the whole length of the speaker wire?

 

[Magslad]

i hadnt though about the conduit being used to put the plaster on! although it does make sense

I was thinking more along the lines of, if at any point I want to replace the speaker wire (without going behing the ceiling or removing floorboards), would it make sense to have a conduit across the whole length of the speaker wire?

If you want to be able to pull the speaker wires right the way through for future replacement (i.e. up one wall, across the ceiling and down the next wall) then you will need pretty large conduit/trunking to create enough space to do this - even then I would think it's touch & go (depending on how long the runs are) whether you would actually be able to pull it all the way through. As Sonic67 pointed out, this will also mean a lot deeper chasing to fit larger conduit and still leave enough gap to get a good plaster finish to tie in with your existing walls (I would guess at least twice the depth that would be required if you were just using standard channelling). Depending on how you are paying your electrician, this may cost a fair bit more as it will be more work.

Theoretically you could do it, but before you do I'd suggest asking yourself just how likely you are to want/need to replace the speaker cabling in the future. You've invested in decent cable which should be fine with whatever speakers you have - if you change anything in the future isn't it more likely to be speakers rather than the cabling?

 

[drdes]

true - i think i will just have the conduit behind the walls

 

[Sonic67]

even then I would think it's touch & go (depending on how long the runs are) whether you would actually be able to pull it all the way through.

My thinking too. You are going around a few 90 degree angles. Usually if rewiring you fasten new cable onto old and pull out the old cable pulling in the new. If when you did rewire the cable got stuck you would still run into problems. I'm not sure why you would want to rewire. Cable doesn't 'wear out'.

You might rewire your house because houses used to use rubber insulation before PVC and rubber does eventually crack. Very dodgy for mains cable.

After WWII rubber was in short supply so plastic was used and it was found to last indefinitly anyway.

You might rewire to meet new needs like for instance these days you need far more sockets in a house than the 50's and 60's. Also you might replace a cable if you had nailed through one.

Otherwise electrical flow is down to the movement of free electrons in a wire and you don't need new electrons.

Conduit is used to make rewiring easier particularly in offices which often uses concrete floors and so conduit might be chased into it but also conduit is used as it provides mechanical protection to the cable and also if steel it is used to provide the earth instead of wiring an earth cable in.