I prefer the wedge because the load will continue to "wedge" or put pressure on the frictional surfaces. I have had inspectors in the past disallow lead as support means in this type of application because in fire they would melt at a lower temp and become one more hazard for the firemen.
#57504 - 10/16/0510:40 PMRe: Hanging Metal Halide fixtures
Be sure to find out beforehand if you've got a "post-tension" concrete structure before selecting any anchors. Post-tension decks can only have anchors that are very shallow without x-raying the deck and getting a structural engineer's OK.
If that's the case, Hilti makes some 3/8" slugs that will do the trick.
#57506 - 10/17/0508:20 AMRe: Hanging Metal Halide fixtures
Ditto on knowing the contruction of the cieling. I was in a building where the sprinkler installer hit a post tension cable, and sent it half way out the side of the building. They had to have re-engineering of the floor loading, after X-raying most of the floor.
Hilti makes a really expensive heavy duty under-cutting anchor that is great for this, but check around, 'cause Hilti has some licensed under other names that are less expensive, and the same product. for instance Toggler (TM) is the same as the Hilti toggle bolt, but 3X as much.
And if you use epoxy, blow out the hole, or you're just sticking to dust.
Mark Heller "Well - I oughta....." -Jackie Gleason