Always Wondered...

As long as its the same voltage, it will not hurt the fixture. Also, dont go over the maximum wattage.

So why can you go under but not over?

I think it's because if you go over you'll be pulling too much power from the transformer and you'll eventually fry it. Also, the light is not designed to take the kind of heat that a higher wattage bulb would produce.

Here's my story. I was fooling with the bulbs in my cosmic. If you take the bulb out of a 2 bulb fixture, it looks really cool. So I wanted to have a some beams bright and some dim. I put a 50 watt in and it immeadiatly burned out THE BULB. DON'T PUT A LOWER WATTAGE BULB IN THAN IT RECCOMMENDS. A higher one will fry the transformer. and a lower one will immediatly burn it out.

And was the voltage of the 50 watt bulb the same as the original 150 watt bulbs? If not, then thats why that happened.

oops, I mean don't put a lower voltage.