I burn ten 75 watt spot lights for twelve hours. I want to burn only every other light for one? hour then burn the other five for the next hour then back to the first five and so on through out the twelve hour day. This would be done with a timer. Question: Does switching five lights on consume more power than the power saved by not burning the other five?

Asker's Rating:

I was unaware that CFL was available in spot light configuration equivalent to 75 W or better. I will pursue this option.

Other Answers (3)

• The amount of power used will be the same, however, you have to take into account the cost of the bulbs and the impact of turning them on and off that often. If they are filament based, they will burn out faster with all the cycling. Not sure about halogen, but I%26#039;d guess that the thermal cycling would also shorten other bulb types too.
• I think for your timer setting, you will save 4.5 kilowatt hrs per day in a 12-hour operation. The calculation is shown as follows:
  10*75*12=9 kilowatt hrs. VS 5*75*6*2=4.5 kilowatt hrs
  The electricity bill is calculated as kilo watt hour(one thousand watts per hour) per unit of electricity cost.
• Save yourself power and trouble: replace the lamps with compact fluorescents, which will burn a quarter of the power. No need for fancy switching schemes, although you may want to have a timer which turns lights on at sunset and off sometime in the middle of the night.