Six fire engines and 35 firefighters and officers were called to a fire at a training centre in Hotspur Way in Enfield.
Part of a canteen area on the first floor of the building was damaged by fire.
Eight people left the building before the arrival of the Brigade. There were no reports of any injuries.
The Brigade was called at 1536 and the fire was under control at 1826. Fire crews from Enfield, Southgate, Barnet, Walthamstow and Edmonton fire stations attended the scene.
The cause of the fire is believed to be accidental and due to an electrical fault in a coffee machine.