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Continuity method 2 on a CPCYou switch the light off mid-test. What changes?

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  1. Isolate. Disconnect the circuit’s CPC from the earth bar, so you’re measuring that CPC alone, with no parallel paths.
  2. Clip the long lead onto the disconnected CPC. Tight — a loose crocodile clip gives a high, wandering reading.
  3. With your other lead, go to every point and probe the CPC terminal. Record the highest reading.
Board CPC off the earth bar R₂ · the CPC alone each point: CPC terminal long (wandering) lead · nulled ohmmeter
One conductor, end to end. Operate a light switch during the test and nothing changes — method 2 never touches the line, so it proves nothing about switching or polarity.
A socket on the circuit? The plug-in adapter is no use here — it puts all your probe points in the socket, and method 2 needs one end at the board. Probe the socket’s earth contact directly instead.

Record it in the R2 column (column 22) of the schedule of test results, and N/A the R1 + R2 column (21). (Using method 1? The other way round.) Put the CPC back on the earth bar when you’re done.

✋For circuits, method 1 is still better.

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