Explosive blasts brought down the tower at the Wabash Valley Generating Station on Saturday morning.
Duke Energy District Manager Rick Burger says mud and debris from the collapsing tower was thrown onto a relay control building. He says that power had to be turned off to make repairs.
The power outage hit Duke customers across the city's north side.
Duke says the smokestack implosion is part of it ongoing demolition of the coal-fired power plant it shut down in 2016.