WiremanWireman · EV charger trips its ground-fault protection: troubleshooting for electricians · 2023 NEC ·
EV charger trips its ground-fault protection
Upstream GFCI vs the charger’s own protection, wiring mistakes, water and the car itself.
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An EV charger has its own personnel protection built in, a charge-circuit interrupting device (CCID) that watches for leakage on the cable and car. A plug-in charger on a receptacle also needs a GFCI on that receptacle under the current code. That means two ground-fault devices see the same current, and the charger’s self-test or normal leakage from the car’s onboard charger can trip the upstream GFCI even when nothing is wrong. Real faults are usually water in the connector or a wiring mistake, like a shared or grounded neutral.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- What trips: the breaker in the panel, or the charger shows a ground-fault light?
- GFCI breaker or receptacle upstreamWhen does the upstream GFCI trip?
- Instantly, even with the charger unpluggedTest: Check the neutral and insulation on the circuitExpect: Correct neutral landing, and insulation readings in the hundreds of megohms or higher.
- Neutral and ground swapped or tied togetherNeutral and ground mixed downstream of the GFCI
- Low insulation readingDamaged or wet conductor
- All correctFaulty GFCI device
- When the charger powers up or charging startsUpstream GFCI conflicting with the charger’s protection
- In rain or after washing the carIs there any chance of water in the connector, handle or car inlet?
- Yes, rain, washing or a wet garageWater in the connector, handle or inlet
- No, it’s dryDoes it also trip with a different car, or does this car trip other chargers?
- Follows the carLeakage in the car’s charging system
- Stays with this chargerCharger or cable fault
- Instantly, even with the charger unpluggedTest: Check the neutral and insulation on the circuitExpect: Correct neutral landing, and insulation readings in the hundreds of megohms or higher.
- Charger’s own ground-fault indicatorIs there any chance of water in the connector, handle or car inlet?
- Yes, rain, washing or a wet garageWater in the connector, handle or inlet
- No, it’s dryDoes it also trip with a different car, or does this car trip other chargers?
- Follows the carLeakage in the car’s charging system
- Stays with this chargerCharger or cable fault
- GFCI breaker or receptacle upstreamWhen does the upstream GFCI trip?