Trainee electrician Frank O'Brien asks a question concerning testing between neutral and earth on a live single-phase circuit with a load connected. It is answered by the ECA (theme - Electrical Testing):
Question: When testing between neutral and earth on a live single-phase circuit with a load connected, I found that no voltage appears on the voltage indicator. Why is this?
The neutral is a return conductor and although it is connected to earth (and is deemed to be at earth potential), 240V should surely show on the instrument when the neutral is carrying current - likewise when testing between the line conductor and earth.
Answer: I do not know the type of installation you were testing, but on most UK installations the earth and neutral will be connected together at the intake so both will be at the same potential, hence no voltage.
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