Firefighters were called to a warehouse fire on Garman Road in Tottenham.
Part of an electrical intake area inside a single-storey commercial warehouse was damaged by fire. There were no reports of any injuries.
The fire was discovered by a member of staff working in an adjoining warehouse who heard a smoke alarm sounding and saw light smoke.
A London Fire Brigade spokesperson said: “This incident shows just how important it is to have working smoke alarms.
“Smoke alarms give the earliest possible warning when a fire starts and we would urge everyone to make sure they have one fitted in every room where a fire can start and a heat alarm in kitchens.”
The Brigade was called at 0909 and the fire was under control by 0945. Two fire engines from Walthamstow and Tottenham fire stations attended the scene.
The Brigade’s Fire Investigators believe the fire was accidental and caused by resistive heating in an electricity meter.