Mains cable in copper pipe

[User]

Hi I plan to run some 3c+e from a boiler to an electric thermostat

I plan to run it through some old now unused 15mm copper pipe covered in tape buried in screed

Can I just run it straight through with no additional action needed?

Or do I have to earth the copper pipe

If I do need to earth can I attach a standard copper pipe clamp and run an earth from it to the incoming water supply 10mm earth clamp?

Any help greatly greatly appreciated please Sparkys!

 

[Click-Sure]

No, you can't do that MontyBurns.

I'd suggest an RF (wireless) thermostat.

 

[streetlighter]

be a bit tight inside 15mm pipe !

 

[User]

ah dang that's bad news dude I was hoping it will be simple may I ask why I can't please?

 

[electronicsuk]

Although Click-Sure stated that "you can't do that", I cannot bring any regulation to mind that would prevent you from running cables inside copper pipe. I think Click-Sure made this statement because your proposed earthing arrangements would be incorrect.

If you run the cable inside 15mm copper tube (which WILL be tight!) then this is effectively an earthed metal conduit, and would probably be considered as such within the installation. However, you can't 'borrow' the earth from your Main Protective Bonding conductors. The pipe will need a suitable earth clamp which should then be connected to either the CPC of the cable running within it, or by means of a separate bonding conductor back to the CU.

Whether or not this is a sensible idea is another question, and I would strongly dissuade you from it, as it's entirely conceivable that a future occupant or tradesman could cut into the pipe on the assumption that it carries water/gas. An RF thermostat as Click-Sure suggested is a much more sensible option.

 

[User]

k electronicsuk i'll follow your advice thanx very much sir

 

[RF Lighting]

The part where you are strongly advised against it I hope?

 

[Spark123]

If you run the cable inside 15mm copper tube (which WILL be tight!) then this is effectively an earthed metal conduit, and would probably be considered as such within the installation.

I wouldn't consider it as suitable as pipe is manufactured to a different BS to electrical conduit.

 

[milliamp]

Monty,
As this is new section of cable I presume it will have RCD protection.
Assuming you can squeeze the 3c+e through the tube, without any damage to the cable sheath, I can see no reason why it cannot be used as a "conduit " for the cable for the distance it is buried in the screed. If the cable is insulated and sheathed the tube would not need to be connected to earth, as would be the case if you used single core cables. How are you protecting the cable before it goes underfloor and when it pops up again?

 

[bernardgreen]

Don't do it if it is a tight fit.

There is a risk the cable insulation will get damaged leaving wires exposed and thus contact with the copper pipe may happen.

Its a high risk if the pipe has been jointed before being buried in the screed.

 

[User]

k thanx for the advice guys

Mr RF Lighting yes correct

Mr Spark123 point taken

Mr milliamp it is RCD protected because the boiler is on the ring mains there is no additional protection

Mr bernardgreen okay it must be a tight fit you're right probaly gonna avoid it then

Thanx for all the advice