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What size/type screws should I use to mount a Raco electrical box bar hanger (Model #920) to studs?

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  • you know how grounding screws must be 10-32? This is nothing like that. This is meant to be "bapped in" by framing guys with whatever they got in their pouch or mag. I would pre-drill and use screws, but only because of my lack of experience not cracking wood. – Harper - Reinstate Monica May 20 '17 at 12:57
  • Not being picky here, but I presume this is to mount something to a ceiling. The horizontal framing members above the finished ceiling are called joists, not studs. Studs are the vertical framing for the walls. – Jim Stewart May 20 '17 at 12:58
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The screw should not be larger than the factory drilled hole which looks to be 1/4". Typically seen in the field are #10 x 1" Slotted Hex Washer Head Sheet Metal Screw.

You can go longer than 1" but for that bar hanger probably not necessary.

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  • +1 The pressure on the screws is virtually all shear (perpendicular to the length of the screw) so length is almost immaterial. Just long enough to grab solidly. There is no tension (pull out) force. – bib May 20 '17 at 1:44
  • The bar hanger pictured is a type used in new construction. It can be used in finished construction where one can go into the attic and get at the ceiling joists, but it really cannot be installed from the living space through an existing hole. If you have a ceiling light fixture in place already and want to install a ceiling fan or a heavy chandelier, then there are other types of bar mount which can be installed from the living space without having to go into the attic. These other types don't even use screws. The bar expands and the ends penetrate into the sides of the ceiling joists. – Jim Stewart May 20 '17 at 12:37
  • One could use any variety of screw or nail, as long as the shank will go through the hole and the head will not, and it has enough depth to not pull out from shear load. So that screw is far more specific than needed, but if you are working in close quarters you will want a drive method like Robertson, Torx, or hex as you picked, which won't cam out. – Harper - Reinstate Monica May 20 '17 at 13:10

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