Boiler frequently trips the main breaker or RCD when heating starts.

Safety first: Do not repeatedly reset a tripping breaker; identify and correct the cause. Isolate the boiler before inspection.

• Confirm circuit rating: Check that the breaker and cable size are appropriate for the boiler's kW rating and phase configuration as per Elnur installation instructions.
• Inspect wiring: Look for signs of overheating, melted insulation, or loose terminals at the boiler and isolator.
• Test elements for earth leakage: Use an insulation tester to check each element to earth. Replace any element with low insulation resistance.
• Check for moisture: Ensure there are no leaks dripping onto electrical components. Repair leaks and dry components thoroughly.
• Upgrade protection (if needed): If the boiler load is within spec but the breaker is underrated, have a qualified electrician upgrade the protective device and cabling as required.