This is about all / any hid fixture which in this example has a 250 watt hps label on fixture. In most or all cases does this mean it is designed for a 250watt bulb or any bulb that has a rating below it labeled size in this case 250 watt hps ? I have come across fixtures with bulbs that have a small wattage then what the fixture is sized at. And when asking why the reply is as long as the bulb is under the fixture rating it is ok. I am thinking about the ballast and believe these people to be wrong.
Anyhelp please, thanks
That theory would work on incandescent fixtures but not with HID ballasted fixtures.
Do a search on Google and use "how does a HID fixture work"
Here is a quick run down, the arc tube inside of a HID type lamp is design to operate at a given voltage and current as well as a given strike/ignite voltage, this is determined by the design of the arc tube with several designs in consideration, such as the length of the tube, the distance between the electrodes, how much mercury is in the tube.
by installing a smaller wattage lamp you now have a smaller of everything I mentioned above, a shorter distance between the electrodes will cause the lamp to draw a higher current from the ballast which will shorten the ballast life exponentially, sure the lamp will strike but it will do so at a higher current, this will cause failures of the ballast and other components, one effect is they will actually draw more wattage and in most cases burn even brighter then the correct lamps.
Short story, I had an operator of a large warehouse who tried to lower his electric bill by installing all 175 watt Mogul base metal halide lamps in the existing 400 watt fixtures, well it lasted a month before I got a call because of failed ballast and or starters, some so badly burned it looked like they caught fire, he tried to get me to replace them under warranty but he forgot to take the 175 watt lamps out, then tried to say we must have put them in, well at first I didn't know so I would check into it, and went to my supplier just down the street to ask for a copy of the invoice for the lamps sent with the fixture, and when I told the counter guy which place it was for he said the manager was in there buying 175 watt lamps and even mentioned that he was buying them to lower their electric bill, well I got a copy of that invoice took it back and showed them ours and his and he just turned red in the face.
