Four fire engines and around 25 firefighters were called to a flat fire on Warltersville Road in Crouch End.
Part of first-floor flat and a second-floor flat were damaged by fire. There were no reports of any injuries.
The Brigade was called at 0837 and the fire was under control by 1022. Fire crews from Holloway, Hornsey, Kentish Town and Finchley fire stations attended the scene.
The fire is believed to have been caused by electrical event involving the electricity meter.