Power was cut to homes in the NN1 and NN2 homes in Northampton after a fire at an electrical sub station.
Around 9.30pm household lights flickered and then cut out as flames were spotted at the sub station next to the Coop in Semilong.
A fast response car and two fire engines were the first at the scene, cordoning off the shop and the area immediately surrounding.
Residents watched from behind the tape as fire officers tackled the blaze with extinguishers and trained a jet of water on the nearby building.
Western Power Distribution said they were hoping to have power restored by 11pm.