Hey folks. I got a question for you guys. Can 50, 80, 100 Watt mercury vapor bulbs be used in a fixture with a ballast rated for 175 Watt bulbs? Or will it smoke the ballast?
The ballast would be OK, it would feed the bulbs by it's 175W (all MV's have about the same arc voltage of around 110V, so the ballast would see the same load as the rated 175W lamp).
But the bulbs won't be happy with that, I guess... (ka-boom) :-D.
With discharges the ballast is the thing what define the current (so power) delivered to the lamp, not the lamp itself. The lamp rating mean the power/current level the lamp is capable to accept for long time and capable to convert it in satisfactory way to the light. But if the ballast feed more, the lamp would run at higher actual wattage and vice versa.
Somewhere here is a picture of 175W MV bulb, what someone run in 400W fixture - the arctube was slightly bulged as a result, but it still survived it for a few years, so the 100W would most likely survive it for some while, the 80W for a short time, but the 50W would melt the arctube and explode very soon, factor of 3.5 overload is really too much...