Electrician Red Seal · Question
An electrician is troubleshooting a frequent nuisance tripping issue on a 480 V, 3-phase motor circuit protected by a ground fault circuit interrupter (GFCI). All insulation resistance readings on the motor and conductors are good. What is a common cause of ground fault tripping that might be overlooked?
Long conductor runs, particularly in underground conduits or armoured cables, can exhibit significant capacitive leakage current to ground. While within accepta
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Question: An electrician is troubleshooting a frequent nuisance tripping issue on a 480 V, 3-phase motor circuit protected by a ground fault circuit interrupter (GFCI). All insulation resistance readings on the motor and conductors are good. What is a common cause of ground fault tripping that might be overlooked?
Answer options:
- High voltage fluctuations on the supply.
- Excessive motor starting current.
- A partially corroded neutral-to-ground bond downstream of the GFCI. ✅ Capacitive leakage current in long conductor runs.
Correct answer: Capacitive leakage current in long conductor runs.
Explanation: Long conductor runs, particularly in underground conduits or armoured cables, can exhibit significant capacitive leakage current to ground. While within acceptable insulation limits, this cumulative leakage can be sufficient to trip sensitive ground fault protection even without a 'hard' fault.
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