Why does my EV charger trip the RCD – Advice from Electriman, North London Electricians

Why Your EV Charger Keeps Tripping the RCD

If your electric vehicle charger keeps tripping the RCD (the safety switch in your consumer unit or garage board), you're not alone — it's one of the most common issues reported after a new EV charger installation.

What Is the RCD Doing?

An RCD (Residual Current Device) monitors the balance of current flowing in and out of a circuit. If it detects a small difference — even just 30 milliamps — it cuts the power instantly to protect you from electric shock or fire. This is a safety feature working correctly, but sometimes it trips too easily.

Most Common Reasons It Trips

Wrong type of RCD fitted — Most EV chargers produce a small amount of DC leakage current. A standard Type AC RCD (very common in older homes) cannot detect DC faults and can be blinded by them, which actually makes it less safe. Many EV chargers require a Type B RCD or a Type A RCD plus a separate DC detection device (6mA DC).

Earth leakage from EMC filters — EV chargers contain internal filters that reduce electrical interference. These can leak a small amount of current to earth, which your RCD detects and trips on.

Nuisance tripping on first connection — The initial surge when the charger handshakes with the car can briefly spike leakage current above the 30mA threshold.

Faulty or ageing RCD — Older RCDs can become sensitive over time and trip at lower than their

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Electriman covers Mill Hill, Barnet, Finchley, Edgware, Enfield, Watford and surrounding areas. All work is Part P certified and fully insured.