A journeyperson electrician is troubleshooting a frequent nuisance tripping issue on a 15 A, 120 V branch circuit that supplies general-purpose receptacles in an office area. The circuit serves six duplex receptacles. With all connected loads turned off, the electrician measures a significant leakage current using a clamp-on ground-fault leakage current meter. After isolating sections, it's determined that the leakage is originating from a specific portion of EMT conduit. Which of the following is the MOST likely cause of the persistent ground fault, considering CEC requirements?

Question: A journeyperson electrician is troubleshooting a frequent nuisance tripping issue on a 15 A, 120 V branch circuit that supplies general-purpose receptacles in an office area. The circuit serves six duplex receptacles. With all connected loads turned off, the electrician measures a significant leakage current using a clamp-on ground-fault leakage current meter. After isolating sections, it's determined that the leakage is originating from a specific portion of EMT conduit. Which of the following is the MOST likely cause of the persistent ground fault, considering CEC requirements?

Answer options:

• Improperly tightened connectors in the EMT system, leading to a poor ground path.
• Exceeded conductor fill in one or more sections of the EMT, causing insulation degradation due to overheating. ✅ Damage to conductor insulation where it passes through a sharp edge or burr inside a conduit body or box.
• The use of undersized bare bonding conductor in the EMT, leading to insufficient fault current clearing.

Correct answer: Damage to conductor insulation where it passes through a sharp edge or burr inside a conduit body or box.

Explanation: Damage to conductor insulation due to burrs or sharp edges inside conduit bodies or boxes is a common cause of ground faults, especially with movement or vibration, leading to persistent leakage current. While improper connectors can cause poor grounding, they usually don't cause leakage current unless the conductor is touching the conduit. Overfilled conduit could lead to overheating and degradation, but direct insulation damage from a sharp edge is a more direct cause of ground fault leakage. The size of the bare bonding conductor (often the EMT itself in this case) wouldn't cause leakage but would affect fault clearing time.