The fire at Yallourn power station that ignited as union members were locked out of the station in an industrial dispute is not suspicious, the Country Fire Authority says.

The fire in the electrical switchboard caused Yallourn station to shut down on Friday night.

Operators EnergyAustralia locked out 75 Construction, Forestry, Mining and Electrical Union members on Friday after a 10-month dispute with workers. Shortly, after the lock- out the fire broke out in the switchboard.

The fire tripped all three units at the power station, shutting them down. It is not expected to affect supply but it did cause the price of power to skyrocket from $50 to $12,500 a megawatt.

Morewell CFA officer-in-charge, Shane Mynard said the cause of the "small fire" was being investigated by Energy Australia but the fire authority has deemed it not suspicious. Mr Mynard said the matter was not referred to police.

"We believe it was an electrical fault that was the most likely cause of the fire because it was in the switchboard," Mr Mynard said.