Disclaimer: This guide is for reference based on standard IEC regulations. Local regulations (such as NEC in the US or specific national amendments) may differ. Always consult a qualified electrical engineer for critical installations.
Australia/New Zealand require minimum 4 mm² earth for power circuits.
The earth wire should be half the size of the phase wire (S/2). Why Does Size Matter? earth cable size chart
For general residential/commercial applications (copper, PVC insulated, IEC style):
If you are using Aluminum instead of Copper, the cable size must be increased significantly to match the conductivity of copper. Disclaimer: This guide is for reference based on
The size of an earth cable is primarily determined by the size of the . In many residential and commercial standards (such as BS 7671 or the NEC), there are specific ratios you must follow to ensure the ground wire can handle the potential fault current without melting. Earth Cable Size Chart (Standard Metric)
| Cross-sectional Area of Phase Conductor (L) | Minimum Cross-sectional Area of Protective Conductor (Earth) | | :------------------------------------------: | :----------------------------------------------------------: | | | 1.5 mm² | | 2.5 mm² | 2.5 mm² | | 4 mm² | 4 mm² | | 6 mm² | 6 mm² | | 10 mm² | 10 mm² | | 16 mm² | 16 mm² | | 25 mm² | 16 mm² | | 35 mm² | 16 mm² | | 50 mm² | 25 mm² | | 70 mm² | 35 mm² | | 95 mm² | 50 mm² | | 120 mm² | 70 mm² | | 150 mm² | 95 mm² | | 185 mm² | 95 mm² | | 240 mm² | 120 mm² | Australia/New Zealand require minimum 4 mm² earth for
For general electrical installations, the minimum size for a copper protective earthing (PE) conductor is often selected using a simplified relationship to the phase conductor ( Sphcap S sub p h end-sub ), provided both are made of the same material: Phase Conductor Size ( Sphcap S sub p h end-sub Minimum Earth Conductor Size ( SPEcap S sub cap P cap E end-sub Same as Phase ( Sphcap S sub p h end-sub Half of Phase (
In domestic settings, standard cable types like come with pre-sized integrated earth conductors (CPCs). Lighting Circuits (6A/10A MCB): Typically use cable with a Socket Ring Mains (32A MCB): Standard cable usually contains a High Power (Electric Showers/Cookers): 7.5kW - 8.5kW: cable with a 9.5kW+: cable with a
| Width x Thickness (mm) | Cross-Sectional Area (mm²) | Approx. Weight (kg/m) | | :---------------------: | :------------------------: | :-------------------: | | | 60 mm² | 0.53 | | 25 x 3 | 75 mm² | 0.67 | | 30 x 4 | 120 mm² | 1.07 | | 40 x 4 | 160 mm² | 1.42 | | 50 x 5 | 250 mm² | 2.23 | | 50 x 6 | 300 mm² | 2.67 | | 60 x 6 | 360 mm² | 3.20 | | 80 x 6 | 480 mm² | 4.27 | | 100 x 6 | 600 mm² | 5.34 |