What is this?
In many UK homes, the socket and lighting circuits are split between upstairs and downstairs, each with their own MCB. When the upstairs circuit keeps tripping, the fault is somewhere in the upstairs wiring or in an appliance used upstairs. Common culprits include bedroom appliances, bathroom fittings, and loft wiring.
Common causes
- Faulty appliance in a bedroom such as an electric blanket, hair dryer, or heater
- Moisture in a bathroom fitting such as a shower isolator or extractor fan
- Damaged cable in the loft where wiring runs between rooms
- Overloaded upstairs ring circuit with too many high-draw appliances
- Faulty socket in a bedroom or landing
- Loft conversion wiring that was done incorrectly or has developed a fault
Is it dangerous?
The same risks apply as with any tripping circuit. Bathroom-related faults are of particular concern because of the proximity to water. If the upstairs lighting circuit is also affected, you may need to use stairs in the dark, which is a fall hazard.
Can I fix it myself?
Identify which MCB has tripped and reset it. Unplug all appliances upstairs and try again. Pay particular attention to bedside lamps, electric blankets, heaters, and bathroom appliances. Plug items back in one at a time. Check bathroom fittings for any signs of moisture or condensation.
When to call an electrician
Call an electrician if the circuit trips with nothing plugged in upstairs, if you suspect a bathroom fitting is the cause, if you have a loft conversion that may have wiring issues, or if the problem is affecting both sockets and lights upstairs.
What will an electrician do?
Identify which upstairs circuits are affected (ring main, lighting, or both)
Test the upstairs wiring with insulation resistance testing
Inspect bathroom fittings, loft wiring, and bedroom sockets for faults
Check any loft conversion wiring for compliance and faults
Repair the fault and test the circuit to confirm safe operation
Typical cost
£100 – £250
Access to upstairs wiring may involve working in the loft. Costs increase if cables are hidden within walls or under floors and need to be accessed.
