Multiple Earthed Neutral Earthing System Defined

Aus/NZ 3000 (known as Australian/New Zealand Wiring Rules) defined Multiple Earthed Neutral as

A system of earthing in which the parts of an electrical installation required to be earthed in accordance with this Standard are connected together to form an equipotentially bonded network and this network is connected to both the neutral conductor of the supply system and the general mass of earth. (AUS/NZ 3000:2007 Clause 1.4.66)

Source: AUS/NZ 3000:2007

The code explained that under this system the neutral conductor of the distribution system is earthed at the source of supply, at regular intervals throughout the system and at each electrical installation connected to the system. 

Within the electrical installation, the earthing system is separated from the neutral conductor and is arranged for the connection of the exposed conductive parts of equipment. 

Characteristic of MEN system

  • All exposed metal parts in the electrical system is earthed
  • There is a link that connects Neutral & Earth connected in the Main Distribution Panel
  • The neutral of the supply transformer must be earthed.
  • The soil where it is to be installed must be effectively conductive

What is the advantage of MEN System?

The main advantage of this system is it achieves lower earth fault loop impedance that can make circuit breaker operate quickly. This is because the exposed conductive parts and extraneous conductive parts are immediately electrically connected to the general mass of earth. Unlike other earthing system like TN-S where the earth connection can be traced back to the source, there is a risk of high earth fault loop impedance that can delay the operation of circuit protective devices in case of fault.

Risk of MEN earthing system

Equipment is still energized even neutral is disconnected

While it is rare to occur, there is specific problem under this system when the neutral of the supply side will be disconnected. In this case the equipment will still operate due to the continuous path offered by the earth connection while the potential 

The current flowing through the earth impedance will cause the protective earth in the system rise above the “outside” earth potential. In extreme cases this could approach the mains supply voltage. 

Possibility of current flow in bonding conductors

Another thing there is a possibility that large currents will flow through the bonding conductors giving rise to a potential fire risk. The magnitude of the current would depend on where the neutral break is, and the earthing conditions in the system.


·         AUS/NZ 3000:2007
·         Electrical Wiring Practice by: Keith Pethebridge and Ian Neeson
·         BS 7671


  1. Just an awesome blog sharing. Truly very very useful and logical information as my opinion. I am very happy to get this info. Thank you so much for your great sharing. Keep it up...
    uat testing

  2. Good Article for OJS trainings. If you need more training Just visit SCG can help you to Get free training on OJS 3.0. Our team will guide you online for complete workflow of OJS.


Select Topics

electric protection Electrical Design power system protection Electrical Safety Fault Analysis Electrical Machines circuit breaker electrical protection protective relaying Electrical Equipment Technical Topics Electrical Installation BS7671 Power System short circuit analysis power system analysis what Earthing System Transformer IEC standard Manual Resources Transmission Lines Unbalanced Fault Analysis electrical testing tutorial video Energy Efficiency Generator ebook electrical motor how substation automation symmetrical components AC Machines Advance Circuit Theory DC Circuit IEC 60364 Renewable Energy Voltage Drop Calculation current transformer schneider electric Circuit Analysis electrical grounding fuse generator protection grid automation motor control power system automation power system stability quiz smart grid switchboard transformer protection ABB Manuals AC Circuit Busbar DC Machines GE Whitepapers Line to Line Fault National Electrical Code arc flash earth fault loop impedance electric vehicle electrical wiring power plant power system operation selective coordination switchgear video tutorial 3D printing AREVA AUS/NZ 3000 Assignment help Busway Current Nomenclatures Electricity Spot Market General Electric IEEE C37.2 IEEE/ANSI Device Numbers MiCom NFPA 70E Philippine Electrical Code Terms of use Theoretical ampacity battery building wiring capacitor circuit breaker curve cooling system cooper bussman disruptive technologies electrical earthing electrical harmonics energy industry engineering education iec 61850 inspection checklist learning protective bonding single line to ground fault transmission line protection voltage transformer voltage unbalance