I purchased (6) 4'x1' t8 fluorescent lights for an unfinished storage room.

My questions is am I best installing these lights directly parallel to the floor joists, or perpendicular to the joists.

In my particular application I would prefer to hang the lights parallel to the joists. My challenge is that the top of the fixture does not install flat to the bottom of the floor joist, as there are several dimples, screw tips. etc... that protrude from the top of the center of the light fixture itself that would not allow me to install the fixture nice and flat. Am I okay installing washers or bushings betwwen the screw holes in the fixture and the joist to allow clearance for the protrusions? Is there another option? I also realize that by installing the fixtures in this manner I will block the topside cable knockouts, but I believe I can use the knockouts in the ends of the fixture.

In addittion, on the existing fixtures that I am replacing, the previous homeowner used the same cable clamp and knockout for the incoming romex as for the outgoing romex that runs to the next fixture. This is not OK, is it?

Thank You.

The protrusions are there for the purpose of creating an air space when mounted on a flat surface, such as a sheetrock ceiling.

Should not matter which direction to mount them regarding the joist. Mount them so you get the best light distribution from the linear (length) of the lamp.

Sure you can use spacers between the fixture and joist to have them mount flat and level.

Having cable run from one fixture to another is fine.

Thank You.

To clarify, I know I can run cable from one fixture to another, but that should not be done using the same clamp, correct? I other words the existing lights have a cable going out the same clamo that has the cable coming in.

Thank you for your help!

Only if the connector can handle to cables. What type do you have?