Earthing of LGS Frames

LGS structural framework must be earthed in accordance with the requirements of Clause 5.4.6 of AS/NZS 3000:2018.

Structural metalwork must be earthed directly (i.e. not via a bonding conductor) with the protective earth conductor connected at one point (5.4.6.2) to the metalwork. The maximum allowable resistance between the earth bar and any part required to be earthed shall not exceed 0.5Ω.  This must be verified in accordance with clause 8.3.5 of AS/NZS 3000:2018. Protective earthing conductor size is determined from Clause 5.3.3 and table 5.1 of AS/NZS 3000:2018. In the situation where parts of LGS frames in a building are not electrically continuous with others, they must be interconnected to meet the requirements of clause 5.4.6.

In general, an LGS frame will be earthed when the electrician returns to site for rough-in of the wiring.

If a temporary electrical supply is installed at the site, a temporary meter box is typically located on star pegs generally near the wall area on which the switchboard will eventually be installed. The earth bar is most likely to be placed at the base of this wall.

A temporary power board for a construction site must comply with and be installed in accordance with AS/NZS 3000 & AS/NZS 3012. Requirements to be met for the connection of a temporary power board to the network may vary between network operators.

All power to a construction site should be RCD protected and correctly earthed.

The images below show two temporary meter boxes.