The Jackson-based utility, a unit of CMS Energy, said the 300-foot crane boom fell onto a building that houses the complex's Unit 3 power plant recently.
Neither the crane nor the plant were in operation at the time, according to officials.
There were about 100 Consumers Energy employees and contract workers in the building at the time of the accident.
One person was taken to a local hospital and later released.
"We've initiated an investigation to determine the contributing factors to the accident," said Dennis McKee a spokesman for Consumers Energy. "There were high winds and I'm sure that the speed of the wind will enter into our assessment of what the contributing factors may have been."
Unit 3 is in the middle of a routine outage for the installation of emissions control equipment.
"We don't know what impact this will have on our outage schedule," McKee said.
Operations at Campbell Units 1 and 2 were unaffected and those units continue to generate electricity.
The Campbell Complex is a coal-fired electric generating facility comprised of three power plants capable of producing up to 1,440 megawatts of electricity. That's enough power to meet the residential, commercial and industrial needs of about a million people.
Consumers Energy provides natural gas and electricity to nearly 6.5 million of Michigan's 10 million residents in all 68 Lower Peninsula counties.