Overdriving a PC bulb?

[Noodle]

Lighting gurus on Maast!

From what I'm trying to understand, it's not the wattage printed on the bulb that dictates the watts going through it, but the ballast that determines it. Am I correct/mistakened/ect?

My dilemma is that I just bought a 27 watt PC fixture that is long enough to handle a ~10" 18w bulb but not a ~12.5" 32w bulb.. Will keeping the 18w bulb in the fixture be okay (aside from the shortened life of the bulb)?

*** Any risk of a fire danger? <--- I hope not as we had a fire sprinkler incident @ work a couple months ago.

Tested the 18w bulb. It fires up just fine when it is turned on, no explosions(!) or extraneous heat output from ballast. But should I still be worried?

[cpreefguy]

If anything, it will significantly shorten the life of the bulb

[alton]

Many of your new ballast are in a nut shell self leveling. Most ballast are built to hold up to a certain number of lamps, as in the old days you would buy a ballast for two T8 32 watt lamps. The Workhorse ballast or the Ice Cap Ballast are perfect examples of do you want to run one, two or three lamps up to a certain wattage. In saying this you will need to find out what kind of ballast you have and go on line and find the wiring diagram for it and see exactly what your ballast will handle.

[Noodle]

Thanks for the info alton. It's supposed to power only 1 set of lights as it's all it's attached to. (sorry if I'm being vague... sorta a lighting noob)

Hmm.. I think I might run into some problems w/ trying to find a diagram, but I will email the ADG guys in Houston to see if they can find out from their Japanese supplier.

Here's the fixture in question:
http://www.adgshop.com/photos/108-062-2T.jpg

And the tech specs I could find on Aquarium Design Group's site.. :wacko
# Input Power: AC 100V (50Hz, 60Hz)
# Consumption Power: 20 W
# Consumption current: 0.39A

[alton]

Input Power: AC 100V, well your feeding it with 120v so your actually are over powering it by 20 volts. Consumption Power: 20 W so with a .98 efficient ballast that would transfer to a 19 watt lamp. But, Consumption current: 0.39A which if you used the same Ohms Law formula 100v x .39 = 39w x .98 = 38 watt lamp, so can you run a 19 or 38 watt lamp, or something inbetween? Does this light fixture have a UL Listed stamp on it somewhere, or does it have just a UL? Listed means tested. Hopefully it is grounded?

[Noodle]

A 27w PC bulb was included with the fixture, and it runs that fine. The 18w bulb I purchased also runs too.
It doesn't have the UL stamp on it - but has the Japanese equivalent, a PSE stamp (the one w/ the circle around it) (http://data.ul.com/denan/EDocs/scheme.html)

It is not grounded though, no 3rd prong on the plug.