I have two 175 watt HPS fixtures that have been out of service for a few years that I reinstalled today. Upon installation and powering up, both these units light up for a while then go off. They immediately relight for a while and go off again continuosley. The one unit will light for only about a minute or two. The other one however will light for a longer period of time, maybe 10 minutes then go off. These are both Hubbel fixtures. Anyone got an answer for this? Is the ballast causing this or what? I can't see both of them doing the same thing. They were working when they were taken out of service the first time. Thanks in advance for any thoughts.
The HPS do have very typical action when the bulb get near end of the life they will cycle on / off due the arc voltage requirement.
over the time the arc voltage rise and when get to the point where the ballast can not able keep the arc on it will go out when cool off it will relit with high voltage starter.
There are few non cycling HPS on market so when they get near burn out useally what they will do is change colour itself going from orange to white-bleuish colour or complety disabled the bulb interally one of the two way.
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)
This is also the way to determine when Metal Halide and Mercury Vapor require re-lamping. Extremely common at end-of-lamp life. I actually find it useful. When they don't cycle, but simply go out, it could also be the ballast or a power issue.