The fire happened around 3:15 a.m. along the 1600 block of Cecil B. Moore Avenue.
Fire crews arrived to smoke showing from under the street and coming from the storm grates, officials say.
PECO was called to the scene to make repairs after it was determined that an underground cable main had overheated.
At about 10:00 a.m., officials said less than two dozen customers were still without power.
Crews hope to have all the power restored by late afternoon or early evening.