Janky Light Hangs

All thread and many pipe hangers and such hardware are great to use because they all have load ratings. I prefer all thread for hanging pipe grids and dead hung battens.
 
It may be "okay" and it may be strong enough, but it's never good practice to use something not rated for the job when hanging things overhead. Ask CB's resident riggers like @MPowers or @What Rigger? what they think about cutting a corner on "probably strong enough" to save a few bucks.

All thread is great for permanent installation... but I question it's use in a portable constantly changing job like a c-clamp extension. I don't know how all thread handles being moved around and rehung all the time and if you don't know you shouldn't do it.
 
You might want to check that math to include loading of the threads and how it factors into the ultimate yield strength rather than just the root areas yield strength.
 
Man, if that's the worse rig that you found than you made out well.

I have seen rigging far worse than that. Other than the lack of safety I wouldn't feel nearly as scared about that as some of the things I have seen in small community theaters.

Not saying that I would build anything like that now.

As another notable point, if anyone feels so unsafe using all thread to hang a fixture than you need to walk into any commercial building and see how EVERY bit of electrical and mechanical is being hung. It is all on all thread, usually 3/8" too.
 
Technically, a cashew is a seed.

What's that? Yes, I know I'm not helping here.


Other than that, another thread that I am so late in getting to that I have nothing to add. :)
All night rehearsals. Boo!
 
Is it strong enough? Probably.

Is it safe? Maybe.

Is it rated for that use? No.

If it fails who will be sued? You.

Should you take the risk? No way! Not when there are rated and approved for that use solutions easily available for a reasonable price. Let City Theatrical or The Light Source be responsible.

Sent from my XT1080 using Tapatalk
I have seen Threaded rod used a lot. I was never really sure, though if it is used to hang hundreds of pounds of HVAC, I cannot imagine that a <10lbs fixture would be a problem, but I'm not an engineer. I agree a actually designed product like you linked to is the best choice. Certainly EMT conduit nuts are not the right choice for holding up lighting.


What is threaded rod made for, and rated for?
 
Threaded rod is designed for overhead suspension. Walk in to a Lowe's or Home Depot and you will see it coming from Unistrut to hang dry-type distribution transformers and such. My opinion is that threaded rod is not the issue as much as the way it was integrated using conduit lock-nuts and a few really bad tack welds (not to mention the modified plumbing fittings). The problem with threaded rod (in my opinion) isn't necessarily the safety of the material itself, but the fact that it is very difficult to adapt a fixture to in a safe and reliable manner. Above all, you would not want to side-load threaded rod. It has almost no strength that way.

I guess we could get in to a discussion about overhead suspension vs overhead lifting. Along those lines, is there a grade difference between all-thread and, say, a yoke bolt?
 
1/2" threaded rod has a vertical suspension load limit of about 1100 pounds. The tensile strength is somewhere along the lines of 60 kPsi. In commercial applications, it's usually used in a system -- that is, there's more than one piece of threaded rod holding that piece of HVAC / conduit / what-have-you up in the air. It would be easy, looking at the OP's photographs, to replace the 1/2" steel pipe with 1/2" threaded rod. It would fit into the stud of the c-clamp, and secured in place with lock nuts at top and bottom. It's a work light, so it wouldn't (presumably) need to be yoked out; straight down works fine. This would avoid the tack welds and re-purposed hardware, as well as save some time -- and look more professional.
 
Again, all this is true about the strength of threaded rod, but you are accepting all responsibility for hanging that light when you choose to use it. My choice is to save my theater budget a few bucks and put myself personally in the position of a huge potential lawsuit if it fails. OR I can make my theater budget pay a little more and hand all the legal responsibility to someone like The Light Source or City Theatrical. To me saving my theater budget a few extra bucks when there is a reasonably priced alternative isn't worth it.
 
Not for nothing, but how many Altman and old Century c-clamps are out there with aluminum stems, that certainly have a weaker side load factor then steel threaded rod ?. And yet everybody and his uncle yokes out fixtures with these clamps.

Those clamps are, in theory, purpose designed and supplied by the manufacturer for this use and we accept that. Even though we know that it's a weak design.

Seems like we are throwing away some common sense when we state that something like threaded rod, which is used in all kinds of similar industrial applications, is not acceptable just because it's not specifically designed to hang a stage light. With steel nuts and washers, I would have no problem with this usage (straight down hang) and I'd bet an engineer wouldn't either.


Sent from my iPad using Tapatalk
 
I appreciate gafftaper's concern of liability - just not convinced that using proper hardware and a safety cable creates much of a problem. But, if someone does not feel qualified to make those design choices, they definitely should not, and buying a piece that is engineered is likely less expensive than hiring an engineer to design the piece and take the liability.

FWIW when we specify portable fixtures, we don't accept cast iron c-clamps or any c-clamp that is not tested and rated by the manufacturer, like the Mega Clamp.
 
Yeah I would love to switch all my c-clamps for mega clamps. Over time I probably will.
 

Users who are viewing this thread

Back