Hi, I just replaced a light and the FS 2 part on my light. Works fine but the bulb keeps going on and off. An fs 2 is for 20 watt and thqt is what I HAVE

Chuck

What size lamp? FS2 is only good for 20 watts I believe.

Yes fs 20 is for 20 watt

If it works for a while, say a half hour or so, then goes off for a while, the ballast most likely is defective or the thermal protector is defective, or the ballast heat cannot escape.

How often does the lamp go on and off?

If it is more frequent, the ballast may be fine, and there may be a loose connection in the power feed, or at any connection at the lamp sockets.