Multiple earthed neutrals (MEN)

Q: Can I have multiple earthed neutrals (MENs) in sheds and outbuildings?

A: Yes - please read the notes in conjunction with the scenario depicted in the diagram below


Notes

This installation incorporates a main switchboard and three distribution boards in separate outbuildings.

At the main switchboard and distribution boards 1 and 2, an MEN connection is required as each earth bar is connected to an independent earth electrode.

There is no MEN connection at distribution board 3, as the earthing is connected directly to the installation earthing system, this is known as a running earth in the sub-main.

The method of earthing a distribution board in an outbuilding must comply with either the system described in b or in c, (as per the diagram).

The neutral conductor supplying distribution board 2 does not rely on a terminal at distribution board in outbuilding 1 for its continuity.

Wiring Rule clauses (specific to this diagram)

  • 1.4.66 Definition of the MEN system
  • 5.3.3 Size of Earthing Conductors
  • 5.3 Main Earthing Conductors
  • 5.5.3 Earthing in Outbuildings and Detached Portions of an Electrical Installation