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Phase rotation, while you're testing supply polarityWhat happens if the phases are in the wrong order?
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Phase rotation is its own test in Guidance Note 3, but you’re already at the supply with your probes out, so it makes sense to do it now. It checks the three phases arrive in the right order: L1, then L2, then L3. Get it wrong and three-phase motors run backwards.
- An approved voltage indicator with L/R lights does it, as above.
- A multifunction tester with a phase-rotation function: three leads on L1, L2 and L3, and it shows the sequence — as 1-2-3, a rotating disc, or simply a pass. Read your own meter’s instructions.
- Guidance Note 3 also names a rotating-disc instrument or an indicator-lamp type.
Guidance Note 3 · 2.6.17 · phase sequence · p.93
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