A faulty exhaust fan caused a lot of smoke but little damage at the CTV London building on Communications Road.
The London Fire Department responded to the offices of CTV London and Jack FM around 4:30 Tuesday morning due to reports of smoke in the basement.
London Hydro says an underground wire that supplies power to the station blew, causing a power surge that made equipment overheat.
The source of the smoke was found to be a defective exhaust fan motor in the lower-level blower room.
There was extensive smoke throughout the lower level that filtered throughout the building, prompting it to be evacuated.
There was no significant damage and no one was injured, but only emergency power was available for staff.
London Hydro crews worked through the day to dig up and repair the faulty line.
Power was finally restored to the building around 4 p.m.
