240V & CPC conductor

[TestEngineer]

I will make an installation for fire alarm system (detectors 240V supply with interlink between of each one) using single wires or pvc cable enclosure in pvc conduit or pvc trucking.The detectors have the symbol of double insulation with out any point for earth terminal and my question is if there is any requirement (17th Edition IEE) to pass cpc conductor with the live conductors as escort?

 

[thebigcheese]

I would include one anyway as no doubt in 5 or 10 years the system might be upgraded to one which does require a CPC

 

[thebigcheese]

And now I've had a couple of minutes to look it up:

Reg 411.3.1.1 of the BGB:

A Circuit Protective Conductor shall be run to and terminated at each point of wiring and at each accessory except a lampholder having no exposed-conductive-parts and suspended from such a point.

 

[Moses]

You need the CPC to do your Zs, or R1+R2 tests.