Question 1

What is AS/NZS 3000?

Accepted Answer

AS/NZS 3000, commonly known as the Wiring Rules, is the joint Australian and New Zealand Standard for electrical installations.  Published by Standards Australia and Standards New Zealand, it is the primary standard governing the design, installation, and testing of electrical wiring and earthing systems in both countries.  AS/NZS 3000 is closely aligned with IEC 60364 and serves a similar function to the National Electrical Code (NEC) in the United States.

Question 2

What earth resistance value does AS/NZS 3000 require?

Accepted Answer

AS/NZS 3000 does not specify a single universal earth resistance value.  Instead, it requires that the earthing system be designed to ensure protective devices operate within the required disconnection time for the fault level at the point of installation.  For MEN (Multiple Earthed Neutral) systems used in Australia and New Zealand, the combined resistance of all earth electrodes at a premises must be low enough to allow the protective device to operate within the time limits specified in AS/NZS 3000 Clause 5.4.

Question 3

What is the MEN earthing system used in Australia and New Zealand?

Accepted Answer

The Multiple Earthed Neutral (MEN) system is the standard earthing arrangement for low-voltage distribution in Australia and New Zealand.  In a MEN system, the neutral conductor is earthed at multiple points throughout the distribution network, including at each consumer's premises.  The consumer's main earthing conductor connects to the neutral at the main switchboard, providing a low-impedance fault return path.  This differs from the North American system, where the neutral-to-ground bond is made only at the service entrance.

AS/NZS 3000: Grounding and Earthing Requirements in Australia and New Zealand