Material constant (e.g., 143 for copper with PVC insulation, 94 for aluminum). 2. The Simplified Method (Selection Tables)
A cable sized perfectly for thermal withstand may still fail if it is too thin to withstand physical stress. earthing cable sizing
Suppose we need to size an earthing cable for a electrical installation with a fault current of 10 kA and a fault duration of 1 second. The soil resistivity is 100 Ωm, and the ambient temperature is 20°C. Using the formula above and assuming a copper cable with a K value of 226, we get: Material constant (e
Often uses bare copper or armored cables for very high currents. Critical Factors Influencing Selection Material constant (e.g.
Formula (copper, 1 second fault):