Conduti for internal cables

[ThePistol]

Hi,

I have recently stripped a room back to brick, and have decided to protect the electrical cables before boarding it up.

What is the best type of conduit to use for:

-cables as part of the ring main
-cables running to lightswitches

Would i be better off using round PVC conduit, or galvanised metal trunking?

Thanks in advance

 

[ban-all-sheds]

Why do you think they need protecting? Against what?

If they are installed in a manner where they have to have mechanical protection then PVC won't hack it.

• http://www.voltimum.co.uk/files/gb/attachments/niu/l/attachments/c5-43.pdf
• http://web.archive.org/web/20061110111450/http://www.niceic.org.uk/downloads/concealedcables.pdf
• IEE article
• IEE Article on 17th Edition requirements for concealed cables.

If it's just your choice then use either. If all you want is to be able to pull additional or replacement cables through in the future then PVC will be fine.

If you want to be able to avoid having to have RCD protection then it has to be steel, but black enamelled will do - it's a lot cheaper than galvanised. Clean and repaint any places where your pipe vice has gripped it and it'll last quite some time. Bear in mind you will need a stock and die to cut threads, and you might find a bending machine useful.

 

[ThePistol]

It was as a personal preference that I intended to protect them. As they are currently exposed I thought it would be worthwhile for the minimal effort / expense.

On your second point re: RCD protection - is this is an existing installation, surely this would not apply as I am simply adding a layer of protection to an existing installation.

RCD protection is not feasible at this stage.

 

[electronicsuk]

On your second point re: RCD protection - is this is an existing installation, surely this would not apply as I am simply adding a layer of protection to an existing installation.

RCD protection is not feasible at this stage.

In that case I wouldn't see it as a problem, assuming you aren't adding additional points etc. It would make sense to put everything into conduit now to save future redecorating if you ever rewire!

 

[ban-all-sheds]

It was as a personal preference that I intended to protect them.

Then you might as well go for your personal preference for conduit. PVC would be a lot less work, steel would mean that if you ever did need to replace the CU you could avoid having the lights on an RCD.

As they are currently exposed I thought it would be worthwhile for the minimal effort / expense.

Steel conduit is neither of those.

On your second point re: RCD protection - is this is an existing installation, surely this would not apply as I am simply adding a layer of protection to an existing installation.

True.

I assume that the cables weren't originally clipped to the surface, or in surface trunking, i.e. you're not going to be concealing them when they weren't before?

RCD protection is not feasible at this stage.

Why not?

 

[ThePistol]

In that case I wouldn't see it as a problem, assuming you aren't adding additional points etc. It would make sense to put everything into conduit now to save future redecorating if you ever rewire!

If I was to add any sockets, then presumably only the new elements would need to comply? Would that mean the new parts would require earthed metal trunking, while on the existing PVC (or none!) would be required? (assuming no RCD protection)

steel would mean that if you ever did need to replace the CU you could avoid having the lights on an RCD.

Would that be a great benefit?

I assume that the cables weren't originally clipped to the surface, or in surface trunking, i.e. you're not going to be concealing them when they weren't before?

they were clipped directly to the brickwork, and plastered over.

RCD protection is not feasible at this stage.

Why not?

I currently have an old style fused consumer unit. I intend to get this replaced At the same time as a number of changes to the circuits in the kitchen. This won't be done until I'm ready to do the kitchen though.

 

[ban-all-sheds]

If I was to add any sockets, then presumably only the new elements would need to comply? Would that mean the new parts would require earthed metal trunking, while on the existing PVC (or none!) would be required? (assuming no RCD protection)

New sockets would require RCD protection.

If you used RCD sockets and the new cables were >50mm deep, or in steel conduit then you wouldn't need to have an RCD for the whole circuit, but that would be a very bizarre thing to do.

Would that be a great benefit?

Less likely to trip, less effort needed to split the circuits over more than 1 RCD or use RCBOs.