Your RCD most likely trips at night due to a faulty appliance switching on automatically — such as a fridge, freezer, or heating system — creating an earth leakage current above 30mA. Start by unplugging appliances on the affected circuit one at a time and resetting the RCD. If it continues tripping with nothing plugged in, the wiring itself may have a fault. Do not repeatedly reset an RCD that keeps tripping — persistent tripping is a safety protection signal and you should call a qualified electrician.
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Why Does My RCD Keep Tripping at Night?
An RCD (Residual Current Device) is a life-saving safety device in your consumer unit (fusebox). It monitors electrical current flowing in and out of a circuit, and if it detects even a tiny imbalance — as little as 30 milliamps — it cuts the power in milliseconds to protect you from electric shock or fire.
When it trips specifically at night, it usually means something is turning itself on after you've gone to bed and creating a small electrical fault called earth leakage.
Most Common Causes
Fridge or freezer compressor cycling — these switch on and off automatically and can develop faulty heater elements or worn insulation over time
Overnight heating systems — electric storage heaters, boilers, or underfloor heating timers activating on a schedule
Dishwashers or washing machines set on a delay timer programme
Outdoor lighting or sockets — moisture ingress into external fittings is worse overnight as temperatures drop
Ageing wiring — insulation resistance drops as cables cool down at night, especially in older properties
Garden water features or pond pumps — these can allow moisture into the circuit overnight
What You Can Safely Do
1. Note the time the trip occurs — this helps identify the appliance if it's on a timer
2. Unplug all appliances on the tripping circuit before bed
3. Reset the RCD — if it holds with everything unplugged, plug appliances back in one at a time over successive nights to identify the culprit
4. Check outdoor sockets and lights for visible water or damage
5. Check the appliance — if a specific item causes the trip, stop using it immediately
When to Call an Electrician
The RCD trips with nothing plugged in
It trips multiple times per night
You notice burning smells, scorch marks, or buzzing from your consumer unit
The property has older wiring (rubber-insulated cables, no earth sleeving)
The fault started after building work or rain
Never tape an RCD in the ON position or replace it with a standard MCB — this removes critical protection and is a serious safety hazard.