There have been many questions on social media about safe isolation tests with specific questions about the voltages to be expected, and the differences between them when testing single phase and three phase boards for safe isolation and before starting work.
And another frequent question concerns reverse polarity – what will reverse polarity voltages look like when the switch is on and what will it be when the switch is off. How do we recognise a reverse polarity circuit?
Many of you will already carry out safe isolation on a regular basis, but for those that are new to the trade, or need a refresher, then we hope that this video will help.
We look at what the measured voltages will be on a good circuit with the power on and compare this to the voltages (or not) that should be expected with the main switch or circuit breaker turned off.
And then we will look at some different reverse polarity scenarios and discuss the dangers of a circuit that is wired incorrectly.
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