It is my practice to surface fasten light fixtures (i.e. flouescent strips) in ceilings using steel drop in anchors. The reasoning being that in a fire the anchors will hold up and the fixtures will not fall on the firefighters.

I was curious if lead anchors or plastic anchors (in a light weight light) can be used or if there is some code on this.

I see a lot of TapCon screws in this sort of work.

Yeah. Tapcons are nice. Some guys shoot a 1/4 x 20 stud too. I never seem to have the gun with me though.

I'm still curious if there is some code on this, maybe even building code.

Another vote for TapCons here, with the addition of a washer - a fender washer if there's enough room.

TapCons are becoming the defacto standard for concrete/block fastening around here until you get up to "red head" sizes.
They even use TapCons for fastening "hurricane clips".

We used to use lead anchors, than we stopped and changed to steel anchors.

We where told it was a code violation to use lead anchors for vertical supports.

I have no idea if it is actually true.

I have found the lighter anchors, of any type, to be inadequate to reliably supporting a light... even a small one!

Tapcons are good, and are the only fastener to use if there is a sheet of steel over the concrete.

Drop ins, or their relativem the "mushroom" stud, are another good choice. The studs seem to help you line things up.

For drywall ceilings, toggles are the only way to go.

Lead has a relitively low melting point, it may be on of the first things to fail in a fire. In dropped cielings I just get the cieling installer to shoot my support wires to the lid. Regular cieling, if I had not already cast in the light or support into the pour, Tap con, and if it's heavy, a lttle epoxy too. If its really heavy I break out the Hilti catolog for the under-cut anchors, and some epoxy... http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-11561

I like a sleeve anchor called a "PowerBolt":
http://www.powers.com/product_06914.html