How to Fix / Troubleshooting

Safety: Do not repeatedly reset an RCD that trips. There may be a serious fault. Isolate the circuit and investigate.

Steps:

Identify trigger: Note whether the trip occurs when the immersion operates, when the boiler is called, or when the pump starts. This helps narrow down the faulty component.
Insulation test: A qualified electrician can perform insulation resistance tests on the immersion, pump, and wiring to locate earth leakage.
Visual inspection: Look for signs of water ingress around cable entries, junction boxes, and the underside of the cylinder. Dry and reseal as necessary.
Component replacement: Replace any component that shows low insulation resistance or visible damage.

Note: Water and electricity are a dangerous combination; if in doubt, call a professional.

Gledhill unit trips the RCD or MCB when heating starts

Possible Causes