For the second straight day, thousands of Met-Ed customers in Berks, Chester and Montgomery counties lost electricity.

At the height of Wednesday's outage, Met-Ed said approximately 4,100 of its customers were without electricity. Much of the problem was in Amity Twp., Berks Co., where Met-Ed reported that nearly 2,000 of its customers -- 41 percent of the township -- were without power at one point.

Hundreds of Met-Ed customers in Birdsboro and Union Twp. Berks Co., and more than 1,200 in neighboring Warwick Twp., Chester Co., were also in the dark for a few hours.

Most customers had their electricity restored by 5 p.m. Wednesday.

The combination of routine maintenance being done in the area and an increased demand for electricity because of the summer-like heat is to blame for the outage, Met-Ed said.

For a time, the outage also affected traffic lights along Route 422 between Monocacy Creek Road and the Berks County line, but police said the electricity to the lights was restored around 3:30 p.m.

The incident, police said, should serve as a reminder to motorists that intersections with non-working traffic lights are to be treated as a four-way stop, according to state law.