A home EV charger usually trips because of water in the charger or connector, a damaged cable, a fault in the car's onboard charger, a circuit that is undersized or shares an RCD, or the charger's own protection reacting to the supply. The first step is to find which device tripped: the charger itself, the breaker in your fuse board, or the whole house. Don't keep resetting it.
Is it dangerous if my EV charger keeps tripping?
Usually not an emergency: the trip is the protection doing its job. But something needs finding, because a charger runs a heavy load for hours. Act straight away if you notice:
- Smoke or fire from the car or charger
- Move everyone away and call 999. Don't try to unplug it.
- Burning smell or melted plastic
- Switch off the charger's isolator or its breaker before touching the cable.
- A hot connector or cable
- Stop charging and don't use it again until it's checked.
- Visible damage
- A cracked case, crushed cable or bent pins. Stop using it.
Which device has tripped?
A trip can happen in three places, and each points somewhere different.
- The charger's own protection
- A fault light or app error. Many chargers have built-in RCD or RDC-DD protection.
- The breaker in your fuse board
- The RCBO or RCD for the charger circuit is down. Sometimes it's in a small separate box.
- The whole house
- Everything is off. Check for a power cut by calling 105, the free power cut number.
What are the common causes of an EV charger tripping?
Water and damage are the most common, then the car, the circuit or the supply. The pattern of trips helps tell them apart.
- Water in the charger or connector
- Trips after rain or washing the car.
- A damaged charging cable
- Driven over, kinked or with scorched pins.
- The car's onboard charger
- If the car trips public chargers too, or another car charges fine, suspect the car.
- An undersized circuit
- The breaker trips after a while at full power, or the cable gets warm.
- A shared RCD
- The charger shares an RCD with other circuits, so small leakages add up.
- DC fault current
- The charger's DC detection trips, pointing to the car or the charger itself.
- Supply voltage issues
- Open-PEN protection cuts out when the supply voltage goes outside safe limits.
What are DC fault current and open-PEN protection?
Both are EV-specific safety features, and both can trip for reasons unrelated to your house wiring.
A car's onboard charger can leak a smooth DC current when it develops a fault. A standard RCD may not see it, so EV circuits need DC detection, either an RDC-DD in the charger, often set at 6mA, or a Type B RCD in the board. If the DC detection keeps tripping, the fault is usually in the car or the charger.
Most UK homes, including most in Leicester, have a PME earth from the network. If a fault on the network breaks the combined neutral and earth conductor, the car's metal body could become live. So chargers on a PME supply need open-PEN protection, usually built in, which watches the voltage and switches off if it goes outside set limits. High or low voltage on the street can trip it; it usually resets itself once the voltage recovers.
Is it a firmware or app problem, or an electrical fault?
If nothing has tripped and the car simply hasn't charged, it's usually a setting. A schedule, your tariff's app, the car's own timer or lost Wi-Fi can all pause charging.
Smart chargers also apply a short random delay at the start of a scheduled charge, as the 2021 smart charging rules require, so a few minutes' wait is normal. Chargers with load management may also pause charging while the cooker or shower is on.
Signs of an electrical fault are different: a switch down in the board, a fault light that returns after every reset, or trips in a pattern, such as after rain.
What can I safely check myself?
You can check the app, settings and cable, and reset a trip once. Anything inside the charger or fuse board is for an electrician or the manufacturer.
- Read the error code
- Write it down or screenshot it from the app.
- Look over the cable and connector
- Check for cuts, crushing, scorching or water in the plug.
- Reset once
- If it trips again straight away or keeps tripping, leave it off.
- Try another charger
- A public charger tells you whether the car is the likely cause.
- Note the pattern
- Time of day, weather and how long into the charge it trips.
Should I call the charger manufacturer or an electrician?
Call the manufacturer for internal error codes, repeated DC detection trips, firmware or app faults, or a unit under warranty. Don't open the charger; that can affect the warranty.
Call your installer or an electrician when the breaker in the fuse board trips, the cable or connections look damaged, or the trips follow rain. They will check the circuit protection, cable size, earthing and open-PEN arrangement, and test the insulation of the charger circuit. If the car is the cause, the dealer needs to look at its onboard charger.
If the circuit needs work, we give one fixed price before we start, and nothing extra is done without your approval.
How can I stop it tripping again?
Good installation and a little care prevent most repeat trips. The charger should have its own dedicated circuit with the right protection. Hang the cable up so it isn't driven over or left in puddles, keep jet washers away, keep the firmware updated, and let either the app or the car schedule charging, not both.
Questions
Why does my EV charger trip only when it rains?
Water is getting in somewhere: the charger case, the cable entry, the connector, or a joint or socket on the circuit. Stop using it in wet weather until it's checked, and don't keep resetting it.
Why does charging stop when I use the oven or shower?
That's often load management working. A sensor on your supply tells the charger to slow down or pause so your main fuse isn't overloaded. If the whole house loses power instead, the load needs looking at urgently.
Can I swap the breaker for a bigger one to stop the trips?
No. The breaker is sized to protect the cable. A bigger one can let the cable overheat. If the breaker trips under normal charging, the circuit or the charger setting needs checking by an electrician.
My charger trips with one car but not another. Why?
That points to the car that trips it, usually its onboard charger or charging cable. Try that car on a public charger. If it trips there too, book it in with the dealer or a specialist.
Will a new consumer unit stop my EV charger tripping?
Only if the board is the cause, such as the charger sharing an RCD with other circuits. Many trips come from the charger, cable or car, so it's worth testing first rather than changing the board on a guess.