Metal conduit

[LoveRocket]

Why does the conduit used for nonRCD runs have to be steel, and not, say, copper?

I know steel conduit will provide mechanical protection, but the regs also allow cable with an earthed metallic covering to be used, so why not an earth metallic conduit - but not necessarily steel - not sufficient to stop a drill, but sufficient to ensure the bit is earthed before it hits a live conductor.

Kind of a 15mm copper conduit...

 

[scott1980]

How would you terminate a piece of 15mm copper pipe into a back box properly?

 

[Monkeh]

Steel conduit is earthed. It doesn't have to be copper to conduct, you know.

Copper is softer and more expensive than steel..

 

[LoveRocket]

Steel conduit is earthed. It doesn't have to be copper to conduct, you know.

Copper is softer and more expensive than steel..

Well strike me down! Everyday's a school day!


I didn't phrase my question very well there; what I mean is why is it OK to use a cable with no mechanical protection but an earthed metallic covering, but not OK to use an earth metallic conduit/capping that doesn't provide mechanical protection.

Erm, I think I've made that even less clear...

 

[Monkeh]

Steel conduit is earthed. It doesn't have to be copper to conduct, you know.

Copper is softer and more expensive than steel..

Well strike me down! Everyday's a school day!


I didn't phrase my question very well there; what I mean is why is it OK to use a cable with no mechanical protection but an earthed metallic covering, but not OK to use an earth metallic conduit/capping that doesn't provide mechanical protection.

Erm, I think I've made that even less clear...

What would be the point of providing a conduit or capping which doesn't provide mechanical protection? Why put all that time and money into it if it doesn't provide mechanical protection, when it's cheaper when it does?

 

[RF Lighting]

Providing you could reliably terminate the end, and could prove that your copper pipe would be suitable for use as a circuit CPC, then I don't see any reason why you couldn't use it.

It is just the norm to use steel conduit as you can get male / female bushes and couplings to easily terminate it into a box and earth it at the same time.

 

[Adam_151]

Conduit has been designed and tested for the proposes of providing containment, copper piping is designed to carry water

If you install cables in pipe, then you'll have a very rough job and one which does not comply with BS7671... but then... its your name on the EIC so what do I care..

If you want to use copper to provide your earthed metallic covering then install MICC....

 

[LoveRocket]

What about steel capping? If it can be properly earthed, would that fulfill the requirements for nonRCD concealed cables?

I think I might just do away with cabling completely and fabricate a bussbar system from copper pipe.

 

[LoveRocket]

does not comply with BS7671....

In what way would it not comply? The cables would be surrounded by an earthed metallic covering....

PS. This is not antsy, it's a genuine question.

 

[Adam_151]

What about steel capping? If it can be properly earthed, would that fulfill the requirements for nonRCD concealed cables?

you tell us...would it meet the requirements of a cpc?.....

 

[Adam_151]

PS. This is not antsy, it's a genuine question.

Materials and equipment should comply with the relevent british standard, coper water pipe is will not comply with the british standard for electrical conduit

 

[sparkwright]

Why would anyone want to use water or gas pipe to run cables in?

The confusion this could cause is endless.

 

[1john]

how are you going to earth it and how can this be verified on a later inspection??

 

[sparkwright]

If you were to use only short lengths for a switch drop or something how would you terminate the ends to prevent the cables chaffing?

And if you wanted a complete conduit system how could you provide inspection points?

And how could you distinguish between conduit and pipework?

And for the mechanical protection it would provide it still wouldn't be as versatile as a pvc conduit.

 

[Paper Spark]

Don't forget about space factor as well.