Hot water
Why an immersion heater trips the electrics
Common causes, why repeated resetting is unsafe and what an engineer should test.
A damaged element is common, but not the only cause
An immersion element can deteriorate and allow current to leak to earth. A damaged cable, local switch, connection or thermostat can also cause a trip, so replacing an element without testing may miss the real fault.
What to do safely
Leave the affected immersion switched off. Do not keep resetting a breaker or RCD that trips again, and do not remove the cylinder cover unless you are competent to isolate and prove the circuit dead.
- Use the unaffected heat source only if it operates normally
- Note which switch or protective device trips
- Check for water near electrical controls without touching them
- Arrange electrical testing
What the engineer should test
Diagnosis normally includes the supply, switching, conductor condition, thermostat operation, element resistance and insulation resistance to earth. The cylinder condition and safe access also affect whether an element can be replaced.
Safety note
Do not remove electrical covers or work on fixed wiring unless you are competent to isolate the circuit and prove it dead. If a breaker or RCD trips again, leave the affected circuit switched off and arrange testing.