Left without electricity at home for more than 18 hours, Kensington resident Toni Kaufman coped yesterday. She transferred perishable food to the refrigerator of one friend and sought air-conditioned refuge at the home of another. In the afternoon she retreated to a public swimming pool.

Kaufman's home was among the 1,500 blacked out by severe thunderstorms in Washington and Montgomery County on Wednesday night, according to the Potomac Electric Power Co. Unluckily, she was also among the 150 to 170 power customers whose electricity wasn't restored until yesterday afternoon.

"In all the other storms we've had this year, the equipment and the people were back in a lot sooner.... Normally [residential electricity] is back in before 18 hours. The outages were so scattered, it just took a while to get to them," said Pepco spokesman Dan Ruskin.

The homes in Kensington, Potomac, Bethesda, Chevy Chase and Silver Spring took longer for repairs because the outages were caused by damage to single wires and isolated fuses. Usually an entire transformer will cut the power for 1,000 houses or more and can be repaired sooner, Rusking said.

New power failures were reported in the Norbeck area as well as other sections of northern Montgomery County after a thunderstorm there last night.