Water heater causes RCD or fuse to trip when it attempts to start
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Do not repeatedly reset a tripping RCD or replace fuses without finding the cause. Risk of fire or electric shock.
User actions:
- Turn off the heater and leave the circuit off until inspected.
- Check for obvious signs of water leaks around the appliance.
Engineer steps:
- Insulation-test the pump, fan, and other loads to identify earth leakage.
- Inspect the PCB and wiring for water damage or burnt tracks.
- Repair leaks and replace any shorted components.
This is a high-risk fault and must be handled by a qualified electrician/heating engineer.
Repair Difficulty
Required Part
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