Transformer-Earthing Wire / Strip Size:
| Size of T.C or DG | Body Earthing | Neutral Earthing |
| <315 KVA | 25×3 mm Cu / 40×6 mm GI Strip | 25×3 mm Cu Strip |
| 315 KVA to 500 KVA | 25×3 mm Cu / 40×6 mm GI Strip | 25×3 mm Cu Strip |
| 500 KVA to 750 KVA | 25×3 mm Cu / 40×6 mm GI Strip | 40×3 mm Cu Strip |
| 750 KVA to 1000 KVA | 25×3 mm Cu / 40×6 mm GI Strip | 50×3 mm Cu Strip |
Motor- Earthing Wire / Strip Size:
| Size of Motor | Body Earthing |
| < 5.5 KW | 85 SWG GI Wire |
| 5.5 KW to 22 KW | 25×6 mm GI Strip |
| 22 KW to 55 KW | 40×6 mm GI Strip |
| >55 KW | 50×6 mm GI Strip |
Panel- Earthing Wire / Strip Size:
| Type of Panel | Body Earthing |
| Lighting & Local Panel | 25×6 mm GI Strip |
| Control & Relay Panel | 25×6 mm GI Strip |
| D.G & Exciter Panel | 50×6 mm GI Strip |
| D.G & T/C Neutral | 50×6 mm Cu Strip |
Electrical Equipment Earthing:
| Equipment | Body Earthing |
| LA (5KA,9KA) | 25×3 mm Cu Strip |
| HT Switchgear | 50×6 mm GI Strip |
| Structure | 50×6 mm GI Strip |
| Cable Tray | 50×6 mm GI Strip |
| Fence / Rail Gate | 50×6 mm GI Strip |
Earthing Wire (As per BS 7671)
| Cross Section Area of Phase, Neutral Conductor(S) mm2 | Minimum Cross Section area of Earthing Conductor (mm2) |
| S<=16 | S (Not less than 2.5 mm2) |
| 16<S<=35 | 16 |
| S>35 | S/2 |
Earthing Resistance value:
| Earthing Resistance Value | |
| Power Station | 0.5 Ω |
| Sub Station Major | 1.0 Ω |
| Sub Station Minor | 2.0 Ω |
| Distribution Transformer | 5.0 Ω |
| Transmission Line | 10 Ω |
| Single Isolate Earth Pit | 5.0 Ω |
| Earthing Grid | 0.5 Ω |
| As per NEC Earthing Resistance should be <5.0 Ω | |
