Downtown Atlanta Street Lights on during the day waste a lot of energy. The average daylight hours for this time of the year is 14 hours. Turning off one 400 watt metal halide street lamp for 14 hours saves approximately 6.70 kWh a day or .64 per day @ .11 per kWh. Thus having one hundred 400w lamps on for the month of May costs approximately $1,940 a month.It also decreases the life of the lamp and ballast and increases the cost of materials and maintenance drastically.
250w HID lamp left on during the day for one year equates to 1,310 kwh annually / $144.14
400w HID lamp left on during the day for one year equates to 2,097 kwh annually / $230.63
1000w HID lamp left on during the day for one year equates to 5,241 kwh annually / $579.58
( Based on .11 per kwh @ 12 hours per day / 365 days a year )