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Orange 'Mains' light on Glow-worm Swift Flow 100

Your boiler is receiving electrical power, but if the light is off, there may be a problem with the electricity supply or the internal circuit board.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Indicates if the mains power is illuminated/available inside the appliance.

What causes this fault?

This issue occurs when the electrical current fails to reach the boiler's control system, either due to a tripped switch in your home's fuse box or a blown fuse inside the appliance itself. It is often caused by a sudden power surge or a failing internal component that has caused the circuit to break for safety.

This fault is more frequent during storm season, as lightning strikes or local power grid fluctuations are more likely to blow the boiler's internal fuses.

DIY fix possible

Check that the boiler's power switch is turned onCheck your home’s main fuse box for a tripped circuit breakerEnsure the fused spur switch near the boiler is turned on

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