Where:
If the phase conductor is Aluminum, the earth conductor is typically sized based on the equivalent copper current-carrying capacity, or calculated specifically to maintain impedance levels.
Selecting the correct size for an earthing (grounding) cable is a critical safety requirement in electrical installations. The earth cable must be capable of carrying fault current without overheating until the protective device (like a circuit breaker or fuse) trips and disconnects the supply. how to select earthing cable size
S=I2×tkcap S equals the fraction with numerator the square root of cap I squared cross t end-root and denominator k end-fraction : Minimum cross-sectional area in mm2m m squared I : The prospective fault current in Amperes.
$$S = \frac\sqrtI^2 \times tK$$
| Conductor material | PVC insulation (70°C) | XLPE (90°C) | Bare copper | |-------------------|----------------------|-------------|-------------| | Copper (Cu) | 115 | 143 | 226 | | Aluminum (Al) | 76 | 94 | 148 |
For specific engineering projects, or when the earth cable is not the same material as the phase cable, you must use the . This formula verifies that the cable can withstand the thermal energy of a fault. Where: If the phase conductor is Aluminum, the
For most international standards (including IEC and BS 7671), the most accurate way to determine the minimum cross-sectional area (CSA) of a protective conductor is using the adiabatic equation:
The standard formula for minimum earthing conductor cross-sectional area is: S=I2×tkcap S equals the fraction with numerator the