Duke Energy offers an energy saving program to its customers called the Power Management program.  Participants have a box installed on their air conditioning unit that cycles the cooling system off for a few minutes during peak usage times.  Approximately 18,000 customers participating in the program experienced an outage.  An incorrect signal was sent to the boxes according to a company spokesperson.  As a result, the boxes shut down instead of cycling.  The shutdown lasted for 3 hours.

An incorrect signal was sent to the energy saving air conditioning control boxes.  Instead of cycling, the units were shut down for 3 hours.