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Posted By Topic: Earthing Arrangement in Units

jasmoon123
Oct 06 2019 16:22

Hi,
A mate wants to upgrade the old existing SwBoard in a Unit (all good so far).


While I was investigating I noticed (all visually) that the Meter Board had a Neutral & Earth with an MEN link. All the MEC's to each Unit are connected to the Meter Box's Earth bar. None of the Units have an Earth Electrode.
I assume this is OK under 3000:5.5.1.1 Exception 1?
The Main Earth Conductor was bolted onto the same stud as the Main Neutral. The Meter Box's MEC seemed to be connected to an earth electrode located directly below the Meter Box. The installation/Units would be 60's or 70's.

The other issue is that the old existing Main SwBoard in the Unit has an MEN link so there would be some 'normal' current flowing in the MEC to the Meter Box's Neutral/Earth bar. Is this acceptable?

Cheers

   

gregmcc
Oct 06 2019 17:00

This was common in older installations, not sure when the rules changed, most likely around 2003 when AS/NZS3000 came into force.