Tension Wire Grid Weight Limit

[carsonld]

Hi All,

I have a tension grid for our FOH "cove" position. I just had a (hopefully) simple question... How much weight can be hung up there. I am wondering as we have two spots there but I am wanting to move my extra lighting fixtures up there to store. I doubt the amount of fixtures I would put up there would exceed the limit, but I just want to make sure. I have attached all the drawings I have of the grid. Apologies for the small print. I am not sure how to get the original drawings as Secoa is no longer in business and Wenger did not get these files when they merged. And the theatre company that installed the rigging system, bought softgoods, etc. is either out of business or just wont respond to my request. I have also attached a picture of the note regarding hanger loads. I am not sure if this is my answer or not.

Anyways, let me know if there is a clear answer hidden in these documents. If not, I will probably hire one of the certified riggers to come take a look.

Thanks!

 

[BillConnerFASTC]

I couldn't study documents but it varies a lot. Probably hangers are good for way more than you could imagine. TWGs have been designed for 15 to 40 psf live load, maybe more somewhere. You really need to track down designers and/or original design documents. Since SECOA was purchased by Wenger, try reaching out to Dan Culhane at Wenger. He would have likely overseen design at SECOA . I look more when at laptop.

 

[RickR]

I see a note saying, lighting pipe live load at 20# per foot. This is a fairly common design load, allowing about one S4 every foot.

Barring other limitations you should be fine.

 

[DrewE]

I see a note saying, lighting pipe live load at 20# per foot. This is a fairly common design load, allowing about one S4 every foot.

Barring other limitations you should be fine.

Just above that there's an additional note (on the second attached document) that the wire grid live load is 20 lbs/sq ft or 350 lbs at the center of one panel.

 

[Van]

Just above that there's an additional note (on the second attached document) that the wire grid live load is 20 lbs/sq ft or 350 lbs at the center of one panel.

So there are a couple different questions here and potential for a lot of different answers. The document we are looking at seems to imply a Lighting batten rating of 20PLF. so a fixture every 1.5 feet or so. the tension grids are not carrying any of that load. Lighting battens are typically attached to strut or the Tension grid Hangers/stanchions. The tension grids themselves are attached to the Stanchions. no load from the lighting battens is carried by the tension grids at all. the note concerning the loading of the grids them selves is in reference to stored goods or items placed on a plywood base. Imagine one big 350# guy standing in the center of a single panel; No one should join him on that panel and he better not be carrying a bunch of cable. Now if he's lying down, you could probably throw another couple guys on the same panel <if you did the math and figured out what their weight is spread over the sq/f they occupy>

All that being said the Tension grid is a terrible place to 'Store' anything. It should be kept clear of everything except working fixtures/acc.s and cables. Do not store pig weights on your tension grid <not that I know why one would.> If you are storing spare fixtures on the lighting battens then OK just don't exceed the 20plf.

 

[spenserh]

I had a similar question last summer about putting large boom lifts on my stage, I can tell you from experience that a few hours of consultation with an Engineer is much cheaper than you might think (even before you factor in the cost of a potential failure).