Problem: Calculated $Z_s$ (0.41) is higher than Max Permitted (0.37). Correction: You would typically either: 1. Increase cable size (reduces resistance). 2. Use a lower $Z_e$ source. 3. Use an RCD (Residual Current Device) for shock protection, which bypasses the overcurrent $Z_s$ requirement for disconnection time.
): Ensure the circuit will trip fast enough under fault conditions. cable calcs
) : Ensure the cable is large enough to trip the circuit breaker fast enough during a fault to prevent electric shock. Professional Tools Problem: Calculated $Z_s$ (0
: Verify the selected cable doesn't lose too much voltage over the distance. Check Earth Fault Loop Impedance ( Zscap Z sub s Use an RCD (Residual Current Device) for shock
: Check standard regulations (like BS 7671 in the UK) for a cable that meets the corrected current requirement.
| Parameter | Value | | :--- | :--- | | | 400/230 V, TN-S | | Design Current ($I_b$) | 120 A | | Protective Device | 125 A Type B MCB (with 30mA RCD) | | Cable Type | XLPE Multicore Copper (BS 5467) | | Installation Method | Cleated in Air (Method E) | | Correction Factors | $C_a=0.96, C_g=0.79$ | | Min. Capacity Required ($I_t$) | 164.8 A | | Selected Cable Size | 50 mm² (Capacity: 176 A) | | Voltage Drop | 6.71 V (2.9%) | | Status | COMPLIANT |