Pretty good guide here:
Hardware on the cabinets for attachment should only be manufacturer's approved hardware for suspension. Not handles, not eye bolts drilled into the wooden
speaker cabinet. Typically the eye bolts will be forged M10's with a fully closed eye. Usually
wire rope or chain up to structure. Sometimes that's open webbed beams, sometimes
unistrut between 2 parallel beams/trusses. Strut is a little nicer because it allows to
drop the
speaker points
plumb instead of doing a
bridle. Bridles aren't as visually attractive if your speakers hang a good distance below the bottom plane of your ceiling trusses.
If it's a 3-point hang, I generally don't worry about a dedicated
safety. If it's a 1 or 2
point hang and a moderately heavy
speaker, I like to take a
wire rope cable along one of the
wire ropes/chains up to structure as a
safety. Usually zip tied to the primary suspension cables/chains. Usually the signal cables are in basically the same bundle as the
safety. Preferably the
safety should terminate at a different
point than the primary suspension cables. If you take the primary points from strut bridged between 2 beams, I would prefer the
safety go up to one of the beams but it depends on the geometry of the hang. A wrecking ball can be more dangerous than a
speaker simply falling out of the air. Obviously this is different too depending on if it's one
speaker that weighs 30 lbs or if it's a
subwoofer or
cluster than weighs 250. Heavier loads need the
safety to be kept close to taut so that if it falls it doesn't
swing or
shock load the cable.
Grade 30
proof coil chain is unacceptable for
overhead lifting but you'll see it commonly. Remember, most PA systems in gyms are installed by electricians, not professional AV contractors. Not the
level of professionalism and
safety we should aspire to but you'll see it a lot in the field nonetheless and generally I wouldn't lose sleep over it unless there are other problems with the hangs. Chain should be rated for
overhead lifting, commonly
STAC or Grade 80 chain.
Shackles should be moused with a
wire so the pin cannot vibrate loose. Especially on subs. But also in a gym speakers get whacked by flying orbs so all connections should be locked down.
No quick links. For that matter, most hardware you get at Home Depot shouldn't be used for overhead work.
There are plenty of other considerations such as
safety factors of materials/terminations, and spans of strut between beams and how you load the strut safely and use appropriate hardware and installation practices.
Always remember the 3 most important rules of rigging:
1) Don't
drop nuthin'.
2) Don't kill or maim anyone.
3) Don't get featured on the AV Install Nightmares or AV Rigging Disasters Facebook groups like these poor schmucks:
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