United Chargers Overcurrent / Short Under Load

Breaker trips immediately or shortly after starting a charge session.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Undersized breaker for configured current, Shorted main contactor or wiring, Ground fault not detected quickly enough, Damaged J1772 cable causing phase-to-phase or phase-to-ground short

How to Fix / Troubleshooting

Safety first: Repeated breaker tripping indicates a serious issue. Do not keep resetting the breaker.

  • Verify settings vs breaker: Ensure the charger’s maximum current setting does not exceed 80% of the breaker rating (e.g., 40 A max on a 50 A breaker).
  • Inspect cable and connector: Look for burn marks, melted plastic, or exposed conductors on the J1772 cable and handle.
  • Internal inspection: With power OFF, check for loose strands of wire, damaged insulation, or signs of arcing at the terminal block and contactor.

If no obvious wiring issue is found, the contactor or internal wiring may be shorted and should be evaluated and replaced by a professional.

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Repair Difficulty

Hard 4/5

Required Part

Main Power Contactor
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