I am installing 400watt metal halide fixtures in a wharehouse with concrete ceilings & concrete beams. What type anchor for the boxes should I be using?
I have had success in the past with lead anchors. They require a set-tool, but they do get a good grip on the inside of the concrete hole.
Another option is epoxy.
1/4 inch wedge anchors(red heads) would hold well also, although lead anchors are quicker and easier to install.
Just a note that these fixtures have some hazards. I'm considering alternate fixtures on my commercial projects.
Dave
coach,
Keep in mind that some concrete ceilings consist of pre-cast slabs, which often have hollow portions.
If thats the case, you may need toggles, or t-anchors.
Lead anchors and wedge's work good for supporting a box. I hope your not planning to hang the fixture from that box, if so epoxey might be better. I has a much higher pull rateing.
Rob
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.
Did a google search and I found this site that compares concrete anchors. The only 2 that are rated for heavy duty are:
http://www.confast.com/products/concrete-strike-anchor.asp http://www.confast.com/products/thunderstud-anchor.asp I use the later all the time. Can be a bit of a nightmare if you screw them. But, they hold really well.
Never tried the first one, it looks kinda interesting though.
Look at the ratings though, 900lbs+ using the 1/4". Plenty strong for a fixture as long as the concrete is in good shape.
[This message has been edited by dmattox (edited 10-16-2005).]
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.
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.
Thanks for the replies. The owner says it is plain solid concrete. I'll try the wedge anchors.
coachman