Most outdoor security lights — an essential safety feature at postal facilities — operate automatically using photocells. But when photocells get dirty or defective, the lights can stay on in daylight and darkness, wasting electricity.
In fiscal year 2007, USPS spent more than $526 million for electricity, with much of the costs used for lighting. If you see an outdoor light that fails to turn off during the day, as shown in the photo, have the light checked.
Most outdoor secu