I was wondering how long HPS lamps can cycle for… I see some die within a few weeks or months after they start cycling. But sometimes it goes for years. There is a long stairway here that has a couple HPS lights that are very difficult to access. In 2012 or 2013, they were abandoned in place and a 1500w MH Was set up at the top of the steps aiming down. The photocells still work, but they have presumably been cycling every night for at least half a decade!