Short answer: A safety device that instantly cuts power if it detects electricity leaking to ground, protecting against electric shock during charging.
Explanation
GFCI (Ground Fault Circuit Interrupter) and RCD (Residual Current Device) are names for the same type of safety device, used in North America and Europe respectively. In EV charging, this protection monitors the current flowing to and from the car. If it detects even a tiny imbalance (meaning electricity is leaking somewhere it should not), it disconnects the power in milliseconds.
Every properly installed EV charging setup includes ground fault protection. Home wallboxes have it built in or require an RCD in the electrical panel. Public chargers have it integrated into their electronics. This protection makes EV charging safe even in wet conditions, as any ground fault triggers an immediate shutdown.
If your home charger trips its RCD repeatedly, it usually indicates a wiring issue, a faulty charger, or in some cases, a known compatibility issue between certain car models and certain types of RCDs. Some EVs require a Type B RCD rather than the more common Type A. Your electrician should verify the correct RCD type for your specific car.
Where you'll see this
- On the charger screen
Common confusion
Some people worry about charging in the rain. EV charging connectors and ports are designed to be waterproof, and ground fault protection adds another layer of safety. Charging in rain is safe with properly installed equipment.
Example
A Type B RCD in a home charging installation can detect both AC and DC ground faults, which is required by some EV manufacturers. Standard Type A RCDs only detect AC faults.
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