Protective earthing requirements

The works of an electrical entity must have an earthing and protection system.

This system must meet a recognised electricity supply industry standard.

It must allow:

• reliable passage of fault current
• reliable passage of single wire earth return load currents to ground or source
• reliable operation of circuit protection devices
• safe step, touch and transfer potentials for all electrical equipment
• appropriate coordination with the earthing and protection of systems of other electricity entities
• protection against likely mechanical damage, inadvertent interference and chemical deterioration
• mechanical stability and integrity of connections.

The Electrical Safety Regulation 2002 (PDF File, 1.02 MB) sets requirements for the works of an electricity entity to minimise electric shock.

• If the multiple earthed neutral (MEN) system of earthing is used:
  • the neutral conductor must be effectively earthed
  • each non-current carrying exposed conductive part of the electric line or generating plant must be effectively earthed.
• Earthing systems must be tested as soon as possible after installation to prove effectiveness.
• High voltage electric lines must be protected by a suitable fuse, circuit-breaker or similar device.

The Electrical Safety Code of Practice 2010 Works (PDF File, 502.0 KB) has more details on protective earthing, earthing conductors and prospective touch and step voltages.