Verma looked at the math.
"It was the earth cable size, sir," Raj said softly, handing Verma the calculation sheet. "The impedance was too high because the cable was too thin. It restricted the fault current, confusing the breaker. And thermally... it barely survived. If we hadn't hit the emergency stop, it would have caught fire." earth cable size calculation
"Trip it manually!" Raj yelled, flipping the emergency disconnect switch. Verma looked at the math
| Error | Consequence | |-------|--------------| | Using the circuit breaker’s rated current instead of the fault current in the adiabatic equation. | Gross undersizing (e.g., using 32 A instead of 800 A). | | Assuming a 0.4 s disconnection time without checking the device’s actual trip time at that fault level. | Overestimation of ( t ), leading to oversized earth—safe but uneconomic. | | Ignoring the minimum fault current when checking touch voltage. | May satisfy thermal withstand but fail shock protection. | | Using ( k ) for bare copper on an insulated conductor. | Overheating and insulation failure. | It restricted the fault current, confusing the breaker