Did the fixtures come with a plug on a cord or are they intended to be hard wired?

The wiring in a fixture is not required to be the same size as the branch circuit conductors feeding the fixture.

It's quite common for lighting fixtures to have thinner wire, because the only requirement at the fixture is to have adequate wiring for the fixture's load, whereas the branch circuit, as brickeyee said, must be capable of carrying the entire load of the circuit, probably 15 amps....so you should be ok.

brickeyee/pjb999,
I think the fixture came out of a building and was meant to be hardwired, it doesn't have a plug or a cord. I bought it from a Habitat for Humanity retail store.
I know you're not suppose to mix gauges in electrical wires so when I saw these smaller gauge wires it kind put a scare in me to wire them together.
Thanks for the feedback.

Nearly all of the florescent fixtures with which I have dealt, are mainly wired in 16ga. The same applies with IC light fixtures, ceiling fans, etc. If you are hard wiring the fixtures, the "trick" when wire nutting this lighter gauge wire to either 12 or 14 ga wire is to make sure you have enough of the lighter wire stripped so it can wrap around the heavier wire to get a good connection. Also, where the romex enters the fixture, be sure to use romex connectors to firmly hold the romex in place.

I have florescent fixtures in my garage that came with plug cords. I wired a receptacle in the ceiling to receive the plugs.

The branch circuit conductors must be sized to carry up to the full breaker rating continuously.

Fixture wiring can go as small as #18 since it is serving a very well defined load.

The minimum size is so that if a fault occurs in the fixture the wiring can carry enough current to trip the breaker.
The temperature rise of the wire is not significant as long as the breaker trips sonce for a short circuit the current will only last a few millisconds.

So far in this millennium, I’ve only seen 18 gauge in fluorescent fixtures. They are solid copper with 90C insulation and 120C on the jumpers between the tombstones but I think that’s asking a lot from a circuit that doesn’t break until (20% over) 20A @ 120V. It’s not like a few feet of #18 is going to burst into flames at 2640 Watts or that you’re going to be bending them several times a day until they break from metal fatigue, but they’re pretty flimsy. Now that I think about it, #18 is probably a safer fuse for “complete fault conditions” than #16 since it’s got pretty good insulation: 18 is 1mm thick and 16 is 1.3mm. Probably a good idea that they’re only used inside a grounded steel enclosure.

Not sure why youd bump a 12 year old thread about fluorescents lamps? No one is really installing them anynore.

Just been trying to come up with the right words. I actually just thought of something else, wait for it….

I'm glad this post was bumped. Just recently I purchased two sets of the same type of lights at The Habitat for Humanity Store. In the same condition as the original post, 18-3 AWG wiring approximately two and half feet long that had been cut off as well. I was trying to figure out if I could use a 3 prong plug to connect each one too or find a way to wire both of them together and just use 1 plug.