Higher watt lamp in luminaire

[jimingram]

I am working in a four year old state of the art private school. I am puzzled that in the exterior recessed luminaires that I'm finding 100 watt metal halide lamps. I needed to pull out the ballast in one of these lumianires and noticed that it was only rated 70 watts. Also, this is not just in one isolated fixture.

I called the local Lightolier rep. to ask how these 100 watt lamps could work on a 70 watt ballast. The rep. called the factory, but that was a futile effort. I've spent the last 25 years on the service truck. I would always match the lamp with the ballast. That's one of the reasons I rarely had a callback. What's especially puzzling is how well these 100 watt lamps work. Typically when I'd find a higher wattage lamp in a lower rated fixture, that lamp was burning dimly. The proper size lamp would burn brighter.

1)How can a 100 watt metal halide lamp work so well with a 70 watt rated metal halide ballast? Multitap ballast 120/277. Ballast operates at 277 volts.
2)Is there any bad consequence for using the higher rated lamp?

 

[yankj]

Surprisingly, 100 watt works in 70 watt metal halide. I've also seen incandescent lamps work in 70 watt HPS The problem is that the 100 watt lamp does not last long.

 

[BullsnPyrs]

shortened Ballast life

shortened Ballast life

if the facility is only 4 years old and you are replacing ballasts already you are also experiencing shortened ballast life.

 

[jimingram]

Thank you. I'm going to have the those 100 watt lamps removed. The ballasts are difficult and expensive to replace.

 

[kwired]

Thank you. I'm going to have the those 100 watt lamps removed. The ballasts are difficult and expensive to replace.

You got that right.

I went through that myself recently. Building is about 10 years old. Lamps were replaced with improper lamps - some were even halogen lamps instead of MH, which does not work. Now a lot of ballasts are no good.