More than 70 firefighters have fought a blaze at the New Zealand headquarters of Fujifilm in Auckland.
Crews were called to the plant at William Pickering Drive, Rosedale about 1am on Wednesday.
The fire had started on the mezzanine level of the building and sprinkers had activated. It took crews about 45 minutes to bring the fire under control.
The fire was initially being treated as suspicious but a Fire Service investigtor says it was caused by a faulty light fitting.
Linda McHugh says a capacitator in a flourescent light fitting malfunctioned and came down on shelving.
She says the building's fire detection equipment worked very well and sprinklers helped to bring the fire under control quickly, meaning there was minimal damage.