no cpc continuity on ring final, strange readings !

[Rockomuir]

Evening all,

Thank you for all your advice recently. I eventually tracked down the a broken cpc in a junction box which was broken where the cable came into the jb not at the terminal. There where also a few loose connections on some old face plates.

Cheers all, just about start my next thread as i need some more advice

 

[Lucien Nunes]

I'm glad the OP has found and fixed his fault, which luckily doesn't sound like it needed the house torn apart to access.

But I don't agree with this at all:

Best way and clearest way to pinpoint the problem would be to firstly liven up the ring affected only... until you reach the leg that fails to give you 230v between line and cpc

The OP says his 'break' measures 300 ohms. A voltage indicator will see straight through that and continue to show voltage beyond the fault. If, on the other hand, the fault does go open circuit, connecting the indicator beyond it will raise the disconnected section of CPC and any associated metalwork to an elevated voltage, and one is then relying on the test current being limited to avoid creating a shock hazard.

My point is this (and it's a point I've made before) Why use a potentially unreliable live test when the fault has been effectively shown up by a dead test? Why would you not continue tracing with an ohmmeter?