Note: For specialized PME (TN-C-S) supplies, the main bonding conductor may have specific minimums, often starting at for residential services. Residential Application Chart (UK/BS 7671 Example)
Before starting your project, always check your local building codes (like the in the US or BS 7671 in the UK). While charts provide a great starting point, a qualified electrician may use the adiabatic equation (
| OCPD Rating (Amps) | Copper EGC Size (AWG) | Copper EGC Size (mm²)* | |--------------------|-----------------------|------------------------| | 15 | 14 AWG | 2.1 | | 20 | 12 AWG | 3.3 | | 30 | 10 AWG | 5.3 | | 40–60 | 10 AWG | 5.3 | | 100 | 8 AWG | 8.4 | | 200 | 6 AWG | 13.3 | | 300 | 4 AWG | 21.2 | | 400 | 3 AWG | 26.7 | | 500 | 2 AWG | 33.6 | | 600 | 1 AWG | 42.4 | | 800 | 1/0 AWG | 53.5 | | 1000 | 2/0 AWG | 67.4 | earth cable size chart
| Service Size (NEC) | Min. GEC – Copper | |--------------------|-------------------| | ≤ 100A | 8 AWG | | 101–200A | 6 AWG | | 201–400A | 4 AWG | | 401–600A | 2 AWG |
Equipment grounding conductor (EGC) size is based on the rating of the overcurrent protective device (OCPD) – not directly on phase conductor size. Note: For specialized PME (TN-C-S) supplies, the main
| Phase Conductor (mm²) | Min Earth (mm²) | |----------------------|----------------| | 1.5 | 1.5 | | 2.5 | 2.5 | | 4 | 4 | | 6 | 6 | | 10 | 10 | | 16 | 16 | | 25 | 16 | | 35 | 16 | | 50 | 25 | | 70 | 35 | | 95 | 50 | | 120 | 70 | | 150 | 70 | | 185 | 95 | | 240 | 120 |
Earth cable size is based on the cross-sectional area (CSA) of the phase conductor (in mm²), with minimum sizes for safety. Note: For specialized PME (TN-C-S) supplies
| 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 |
*Approximate mm² conversion for reference only – use AWG for NEC compliance.