lighting circuit no cpc arguement.

[JACKC]

Peeps, can you help settle this difference of opinion at work.
Lighting circuit with no cpc, I say run in a seperate earth core throughout the whole of the circuit back to the consumer unit. My mate says its ok to just link it to another circuits cpc such as the ring main. I personally don't like that idea but could not answer the "show me the reg that says I can't"
TIA.

 

[Wangerman]

Essentially all earth goes back to a central point. I would link from the nearest available earth and would leave a note by the fuseboard

 

[securespark]

It is acceptable to run a separate cpc for such a circuit, but the cpc ought to be run adjacent to the existing cabling.

As for hacking into another circuit for a connection, thats just butchery. Exact reg references escape me at the moment, but such a practice is extremely poor.

EDIT don't have current regs here, but, from the 15th ed:

"314-1 Every installation shall be divided into circuits as necesary to-

(i) avoid danger in the event of a fault, and

(ii) facilitate safe operation, inspection, testing and maintenance."

I know this reg is current in the 17th.

Would hacking into another circuit to rob a cpc connection comply with this reg?

 

[PrinceofDarkness]

Jack: If you say that a separate earth should be carried all the way to the CU, then you might just as well replace the twin feed with a T&E cable.

There's nothing wrong with your mate's suggestion to take a reliable earth from another circuit close by. After all, if you have such an installation, it's on borrowed time anyway........



Lucia.

 

[ricicle]

But remember a seperate cpc to another circuit would have to be minimum 4mm²

 

[PrinceofDarkness]

Not necessarily Ricicle. A 2.5mm unsheathed single cpc would be more than adequate for a 6A lighting circuit - provided that it's protected against mechanical damage. If it's running in a celing void for most of its length then it would be so 'protected'.

Good God! Even a 1mm separate cpc in those circumstances would do the trick for a lighting circuit. Anything is better than nothing......



Lucia.

 

[riveralt]

Peeps, can you help settle this difference of opinion at work.
Lighting circuit with no cpc, I say run in a seperate earth core throughout the whole of the circuit back to the consumer unit. My mate says its ok to just link it to another circuits cpc such as the ring main. I personally don't like that idea but could not answer the "show me the reg that says I can't"
TIA.

If it has worked okay for thirty or forty years without a CPC why does it need one now? I'm coming across quite a few instances of houses without lighting CPC and while I give advice to 'upgrade' I don't know of anything in writing that makes it mandatory.

 

[Wontdothatagain]

As riveralt says, as long as you dont have class1 equipment on the circuit, it complies.