Electricity company Fortum says that the power cut kicked in at 2:23pm Friday. The reason is not yet known.
The outage affects around 4,700 customers. The fault patrol has been sent out to the isolate the problem, according to Fortum.
"The extent of the power cut is due to the fact that the power supply systems are on the northern side of Pori owing to exceptional network maintenance. If a fault occurs, it will affect a wider area than normal," says Fortum’s Operations Manager Mikko Tegel.
Normally the Noormarkku area is divided into 5-6 zones, meaning the fault would usually have been limited to only one region.
Tegel estimates that the area affected by the outage could be significantly reduced by 4pm Friday. After that time the cut is likely to affect only around a tenth of those initially hit by the blackout.
Overall, Tegel estimates an outage lasting around 2-3 hours.