Widespread power cuts were reported in several areas around Malta and Gozo after the distribution switchgear of the Marsa south distribution centre blew up during re-enforcement works.
No one was injured but a number of employees were sent to hospital for observation. Power was restored by 6.45pm.
Enemalta said the fault caused the two units at Marsa Power Station - Turbine 6 and Turbine 7 - together with the steam units and gas turbine at Delimara Power Station to trip.
The only generating units that did not suffer a trip were the diesel engines at the Delimara extension.
As a result, 55 per cent of the island suffered a power cut.
The corporation said investigations are underway to find the cause of the explosion.