Your EV charger trips the RCD most commonly due to high earth leakage current from the charger's internal EMC filter capacitors — this is normal but can exceed your RCD's trip threshold. First, check whether the dedicated EV circuit uses a Type A or Type B RCD, as many EV chargers require a Type B (or Type A + DC detection device). If a standard Type AC RCD is fitted, it must be upgraded. Call a qualified electrician if the fault persists — do not repeatedly reset and retry.
🏠Homeowner view
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 rated threshold.
Damp or moisture ingress — If your charger or the cable run passes through a damp garage, shed, or external area, moisture can cause leakage.
Faulty charger unit — Less common, but the charger itself may be defective.
What You Can Safely Check
Check what type of RCD is installed — Look in your consumer unit for a label. If it says 'Type AC', this likely needs upgrading.
Check for visible damage to cables, the charger unit, or any signs of moisture.
Check your charger's manual — It will specify the required RCD type.
When to Call an Electrician
You should always call a qualified electrician (ideally one registered with NICEIC, NAPIT, or a similar body) if:
The RCD trips every time you plug in
You are unsure what type of RCD is fitted
There are signs of burning, smell, or scorch marks
The installation is less than a year old — it may be incorrectly installed
Do not keep resetting and retrying the RCD without investigating — repeated tripping can indicate a genuine fault.