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Supply polarity, single phase: three readingsNeutral to earth reads 230 volts. Now what?

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L – N 230 V L – E 230 V N – E 0 V any other combination = incorrect supply polarity · stop
Line is the only conductor at 230 V to anything. Neutral and earth sit at, or very near, the same potential — on TN-C-S they are joined in the supply, so some indicators give a continuity beep rather than a voltage between them.
✋Anything else, stop. No further live tests. You and anyone else on the installation are in danger. Find out where it’s reversed — the main switch, the meter, the supplier’s equipment — and get it put right by whoever is responsible.

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