This diagram provides guidance for checking the continuity and polarity of ring final circuit conductors with no spur for compliance with Regulation 612.2.2.
This should be viewed as a continuation of the post: Checking the continuity of a ring final circuit.
- Ensure installation, or appropriate part of it, is securely isolated, and proved to be so, before proceeding.
- Cross-connect the incoming phase with the outgoing circuit protective conductor (CPC) of the circuit and vice versa. Measure the resistance of phase and CPC and note the result.
- The measured value at each socket-outlet and at the consumer unit should be substantially the same. his measurement would be (r1+rn) or (1 + rn)/4.
- Correct verification of rings also proves correct polarity but only on ring circuits.
The next diagram from Megger shows how you can check the continuity of ring final circuits with unintentional spurs.