Originally Posted by Gumby
Couldn't you just wire in an appropriately sized resistor if you were worried about the current?
An incandescent bulb is not a linear resistance. It is a low resistance when cold, and increases in resistance when hot. They are sometimes used as current limiters.
Since this incandescent bulb is in series with the UV, it might be part of the design to provide a high in-rush current for the first fraction of a second to start the UV bulb and then limit the current once the UV 'fires'.
It's hard to say w/o more info, sometimes the wiring in series is done so you know if there is a fault or not ( which makes sense for this application ), but it could also be a current limiter for the UV bulb, if the ballast transformer isn't already providing all the current limiting.
Could you put the connectors on in such a way that you replace the UV bulb, and leave the rest of the circuit in place? I'm guessing that they are running the incandescent bulb at below it's rated current - it could have a life-span grater than your portfolio....