User: Miguel c, Location: Barranquilla colombia
Asked on: Thursday, May 27, 2021 at 7:35 pm EDT
Answered on: Thursday, June 20, 2024 at 10:53 am EDT
Question: Suppose we have a line at 120 V 200 ft long 3 AWG wire, impedance 0.05 ohmsCircuit breaker lets say is a 200 A oneNow there is a grount fault and we have a 14 AWG EGC wire, 200 ft long, (violation) the EGC's impedance is 0.6344 ohmios, therefore the graunt fault current is 175 A, hence the breaker does not trip, now the metal parts are energized. Would that provide the potential for electric shock taking into account we still have an effective ground fault current path and the neutral is bonded to ground?
Yes, the energized metal parts would provide the potential for electric shock.
Explanation: The ground fault current path is incomplete because the EGC (equipment grounding conductor) wire is not a proper conductor for the purpose of clearing a ground fault. It has too high an impedance of 0.6344 ohms, so the ground fault current is insufficient (175 A) to trip the 200 A circuit breaker. The circuit breaker will not trip, and the neutral is bonded to ground, so the metal parts become energized. Anyone touching these energized parts could experience an electric shock because the current will flow through their body to ground.The situation is dangerous because: The circuit breaker is not providing protection from the ground fault, so the fault can persist indefinitely. The energized metal parts create a potential for electric shock even though there is an effective ground fault current path.To resolve this issue, the 14 AWG EGC wire should be replaced with a proper conductor for clearing ground faults, such as a 3 AWG copper wire. This will ensure that the ground fault current is high enough to trip the circuit breaker and protect against electric shock. Flag for review