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How the R1 + R2 test proves polarityThe light works. Can the polarity still be wrong?

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This is the part that makes method 1 more than a CPC test. Put your probes on the terminal marked for the line, and the terminal marked for the CPC — not on wherever you can see the brown conductor go.

Correct L terminal → brown (line) E terminal → CPC reads continuity L and N swapped L terminal → the neutral neutral isn’t in the linked loop reads open circuit fault found
The link at the board joins the line and the CPC only. If the neutral is sitting in the line terminal, your probe is on a conductor that isn’t part of the loop, and the meter shows open circuit — even if you missed the crossed conductors on inspection.

Inspection should catch crossed conductors — but a terminal in a dark corner is easy to miss. Testing at the marked terminals is the second layer: if the neutral is in the line terminal, the meter tells you.

The one swap it can’t see. Line and CPC swapped with each other still give a normal reading — they’re the two conductors you linked at the board. Only looking at which conductor is in which terminal finds that one.
✋Open circuit where you expected a reading? Before you blame the switch, check what’s actually in the line terminal. Operate the switches; if it still reads open, suspect polarity.

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