Electrical workers fail to use independent earth for polarity testing

The Queensland Electrical Safety Office (ESO) is reminding electrical workers to use an independent earth whenever possible, rather than the installation earthing system.

Recent disciplinary hearings have involved workers failing to ensure the correct polarity of supply after performing work on the incoming service. The Electrical Licensing Committee noted that in many cases electrical workers failed to use an independent earth when conducting polarity tests.

"An independent earth provides a zero voltage reference, free from voltages which may be present in the bonded earthing system of the installation, which is preferred for the correct identification of polarity. AS 4741 Testing of connections to low-voltage electricity networks is referred to by supply authorities, their subcontractors and ESO inspectors when testing low-voltage services for correct polarity. It provides that when testing polarity, unless the earthing system is proven to be isolated from the neutral, an effective independent earth must be used," said Queensland ESO in a statement.

Independent earths should be driven into the ground at least two metres away from the main earth stake, meter box, water pipe and any other earthed conductive parts associated with the installation, the statement said.

"Incorrect polarity can result in dangerous electric shocks and property damage. Always use an independent earth where possible."

Image credit: Queensland ESO.