Switching power lines to make way for the new Home Depot cut off power to 2,400 Lawrence electric customers Thursday and left hundreds of junior high students wondering what to wear this morning.

A switch failure near Home Depot’s construction site near 31st and Iowa streets triggered the power outage at 12:08 p.m., blacking out homes, businesses and five schools in an area bound by 19th, Louisiana, 31st and Iowa streets.

All customers were back on line by 1 p.m., Gina Penzig, a Westar spokeswoman, said.

The outage, however, left a lingering problem. It knocked out a boiler pump at South Junior High School, disabling the building’s heating system. This prompted school officials to advise students to be prepared today in case the system isn’t repaired.

“Dress accordingly,” said Julie Boyle, a spokeswoman for the Lawrence school district. “With the nice weather, the building should be able to hold enough heat overnight to be fairly comfortable for school.”

Lawrence High School and Broken Arrow, Centennial and Schwegler elementary schools also felt the hit of Thursday’s outage.

Students at Centennial were evacuated briefly after the smell of smoke wafted into the building from a rooftop motor, Boyle said. Students soon returned to class without incident.

Penzig said the outage came as electric flows were being switched from one line to another so that crews could install a new line to serve the new Home Depot and surrounding area.