The average % of lamp life chart indicates the average age of lamps in a system based on the number of lamps each year. The table below shows an example of this calculated for a system with a 100 lamps, each with a 3000 hour rated life, where 25% of the lamps are replaced every 2 years.
| Lamp Burn Hours | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Year | 0 | 3,000 | 6,000 | 9,000 | 12,000 | 15,000 | 18,000 | 21,000 | Lamp Hours | Ave |
| 1 | 100.0% | 300,000 | 25% | |||||||
| 2 | 25.0% | 75.0% | 450,000 | 38% | ||||||
| 3 | 25.0% | 75.0% | 750,000 | 63% | ||||||
| 4 | 25.0% | 25.0% | 50.0% | 750,000 | 63% | |||||
| 5 | 25.0% | 25.0% | 50.0% | 1,050,000 | 88% | |||||
| 6 | 25.0% | 25.0% | 25.0% | 25.0% | 900,000 | 75% | ||||
| 7 | 25.0% | 25.0% | 25.0% | 25.0% | 1,200,000 | 100% | ||||
| 8 | 25.0% | 25.0% | 25.0% | 25.0% | 900,000 | 75% | ||||
| 9 | 25.0% | 25.0% | 25.0% | 25.0% | 1,200,000 | 100% | ||||
| 10 | 25.0% | 25.0% | 25.0% | 25.0% | 900,000 | 75% | ||||