Some professional lighting contractors believe that all of the lamps should be replaced annually. This is in part because many of the lamps commonly used in landscape fixtures have an average life of 2000 hours and many residential systems are on an average of 2000 hours each year. The key word is average. Check your lamp schedule to determine the range of average lamp life for the different fixtures in your system. Remember that lamp life is specified as an average. The average is determined by the time the 50^th lamp in a one hundred lamp batch lasted. Forty nine of the lamps burned out sooner, 50 lasted longer.

What your annual usage going to be? If you only use the system when entertaining, it may be considerably less than 2000 hours. If the system is primarily for security, then the usage may be well over 2000 hours. Even your location may have an impact on how long you will be able to go before having to re-lamp. Southern latitudes have more sunlight and therefore have lower usage hours than those in the North.

So while setting an annual schedule to replace all of the lamps may be convenient and easy to remember, it may not match your system needs or usage pattern. If you like the idea, then simply make some rough estimates of average lamp life based on the lamps used in your system and how you much you expect the system to operate. Don’t waste a lot of time on the calculations because the data that you’re working with is very inexact. You may find it better to replace lamps as they burn out with some spares that you keep on hand. It only takes a minute.