How do I wire a new ballast to my fluorescent light fixture if the old one had only one red and one blue wire, but the new one has two blue and one red. There are no yellow common wires on the other end of the light.

Only two things to consider. First of all, do you have the right ballast? Secondly, if the ballast does NOT have the wiring diagram on it, get one that does.

It has a wiring diagram, but there are no wires on the other side of the lamp to attach the red wire to.

Nicole,

You have the wrong ballast. It sounds as if you have a ballast for a single bulb fixture instead of a two bulb fixture.

Can you tell us which bulb(s) you have in the fixture? Perhaps we can tell you which ballast to use. Do you know if the fixture has a starter?

I figured it out. It was the right one, just had to cap off one of the blue wires. Thanks anyway!

Glad you got it figured out.