I have a 24 in. flourescent fixture, single tube, open design with no lens or shade. UL listed for dry locations only.

Is it safe to mount this fixture to the bottom of a wooden shelf (in my utility room)?

This would put the side of the fixture that has the ballast mounted to it right against the shelf. My concern is the note inside the fixture that states that supply wires located within three inches of the ballast must be rated for 90 degrees C. In my experience, ballasts become quite warm, even hot.

Are these fixtures designed to be mounted to surfaces, or only to be hung by chains?