Using a conduit sysem as the CPC

[EddieB]

I added an additionl socket to the existing ring in a block of flats the other day and there was no seperate earth conductor,the conduit was acting as it. I moved the circuit to a new consumer unit so the ring was now protected by a RCD. When it comes to filling out the test schedule what do I enter in the R1+R2 column. I assume you enter NAis this correct and if not whats the next move.

 

[chocolate]

You must have an R1+R2 value. Saying N/A implies that it isn't required or doesn't apply to this circuit. It does. The procedure is slightly different but you should get a measurement.

Without it, you're saying there's a problem.

 

[andekoch]

You measue the R1 + R1 as per usual and make a not on the certificate that the CPC function is being performed by the earthed metallis conduit.
You need to confirm that this is the case and that there is a CPC connectign the back box/ installation box terminal in the wall to the earth terminal on the face plate of the accessory.
It would be a good idea to put a lable on the consumer unit stating that the conduit is used as the CPC and must not be compromised.
This is a acceptable way of prociding a cpc, not to mention the mechanical protection for the cables.

 

[EddieB]

I suppose the only way to test the R1 + R2 is to use the wandering lead method, thanks all!