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Author Topic: Hanging fixture from uni-strut  (Read 26765 times)

Eric Cole

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Hanging fixture from uni-strut
« on: April 04, 2011, 08:26:51 pm »

I mix for a portable church and need some help with lighting.   Our stage sits infront of a large southern facing window and I can not get enough light from the pair of trees with source 4 jr's that are have at least a 50ft throw. I wish I could get them closer.   There is uni-strut in the ceiling that I would like to hang a par cans from stage left and right, but I need them to drop down 3ft to clear a soffit.   My initial thought was to use a mega-airwall hanger, a pipe coupler and some steel pipe.   There has to be a better and more volunteer friendly solution than this.  What do you suggest 
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Philip Roberts

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Re: Hanging fixture from uni-strut
« Reply #1 on: April 04, 2011, 11:45:43 pm »

I mix for a portable church and need some help with lighting.   Our stage sits infront of a large southern facing window and I can not get enough light from the pair of trees with source 4 jr's that are have at least a 50ft throw. I wish I could get them closer.   There is uni-strut in the ceiling that I would like to hang a par cans from stage left and right, but I need them to drop down 3ft to clear a soffit.   My initial thought was to use a mega-airwall hanger, a pipe coupler and some steel pipe.   There has to be a better and more volunteer friendly solution than this.  What do you suggest
Take a page from the building trades handbook.

I'd think that you could hand a Par off of a piece of all thread jam nutted against washers into a unistrut spring nut. Just attach that par to the lower end of the all thread. I'd still have a safety cable.

Philip
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Lee Buckalew

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Re: Hanging fixture from uni-strut
« Reply #2 on: April 04, 2011, 11:52:04 pm »

Take a page from the building trades handbook.

I'd think that you could hand a Par off of a piece of all thread jam nutted against washers into a unistrut spring nut. Just attach that par to the lower end of the all thread. I'd still have a safety cable.

Philip

You would still be required to have a safety cable.  Also, Unless things have changed, Unistrut is not rated for overhead suspension. 

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Ray Cerwinski

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Re: Hanging fixture from uni-strut
« Reply #3 on: April 05, 2011, 12:51:19 am »

How about a Uni-bolt with a Mega-Drop Down from The Light Source?

http://www.thelightsource.com/products/45/view

http://www.thelightsource.com/products/82/view

note: i am a light source dealer.
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Ray Cerwinski

Craig Leerman

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Re: Hanging fixture from uni-strut
« Reply #4 on: April 05, 2011, 02:57:46 am »

Also, Unless things have changed, Unistrut is not rated for overhead suspension. 

Lee Buckalew
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INCORRECT

Unistrut is indeed rated for overhead suspension. That's why you see things like HVAC and air handling components, electrical components and other building items suspended by Unistrut in commercial buildings.  In fact, in most ballrooms and showrooms here in Las Vegas, Unistrut is built into the ceilings as a standard decor and lighting rigging point. (Yes, they have larger points for motors!) A brand new venue here in town (MEET Las Vegas) not only installed Unistut all over the ceiling, but down the walls as well to facilitate lots of rigging options.

While the rating for any particular installation is dependent on the type and size of track used, and how it is mounted and installed, the components are indeed rated for overhead suspension.

Here is a page from the Unistrut website showing horizontal and vertical loading. For example, a horizontal 1 1/4" track 48" long supported at both ends can support a Uniform Distributed Load (UDL) of 360 pounds. 

http://www.unistrut.us/index.php?WP=cat_detail&S=S05&P=A1000

Craig
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John Livings

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Re: Hanging fixture from uni-strut
« Reply #5 on: April 05, 2011, 04:31:38 pm »

INCORRECT   +1

[Unistrut is not rated for overhead suspension.] 

We have used Unistrut to support #1000s of pounds of Conduit, Pipe, AC Ducts and many times the entire AC/Heat pump unit and lots of other Stuff, No problems, All Inspected.

A simple way to get 3 feet lower than the existing ceiling is to use 2,3,5 or more pieces of 1/2 inch "All Thread"

and attach another piece of unistrut hung 3 feet below the first piece.

I would inspect the existing Unistrut to be sure it has been installed correctly.

It is done everyday.

Regards,  John
« Last Edit: April 05, 2011, 07:23:00 pm by John Livings »
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Lee Buckalew

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Re: Hanging fixture from uni-strut
« Reply #6 on: April 06, 2011, 08:14:25 am »

INCORRECT   +1

[Unistrut is not rated for overhead suspension.] 

We have used Unistrut to support #1000s of pounds of Conduit, Pipe, AC Ducts and many times the entire AC/Heat pump unit and lots of other Stuff, No problems, All Inspected.

A simple way to get 3 feet lower than the existing ceiling is to use 2,3,5 or more pieces of 1/2 inch "All Thread"

and attach another piece of unistrut hung 3 feet below the first piece.

I would inspect the existing Unistrut to be sure it has been installed correctly.

It is done everyday.

Regards,  John

What it has been used for has no bearing on whether it actually carries an engineering rating for overhead suspension.  I was told by an engineer on a project that it does not and, I can't find a rating listed anywhere.  What makes it rated when used in construction is a set of drawings being signed off on (and stamped) by a structural engineer and the construction then following the drawings. 
Even if individual pieces carried an overhead suspension rating you could not build them into a system and have it be rated for overhead suspension unless that exact system also carried a rating.  It's the same as speaker rigging.  I can buy overhead suspension rated components and build them into my home-made speakers (or store bought speakers with no rigging provision) but, unless the system is rated as a whole, my speakers are not rated for overhead suspension despite my using rated components.

I may be wrong on Unistrut not carrying an overhead suspension rating, please inform me as to the rating and the rating standard if it exists and stop telling me what it's been used for.

You are correct that "It is done everyday."  I was just pointing out that it may not carry a proper rating once this was done which could have an impact if there were a future problem.  People put their own "rigging" in speakers everyday also, it does not make it safe or something that will be O.K. with an insurance company if there is a problem.

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Craig Leerman

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Re: Hanging fixture from uni-strut
« Reply #7 on: April 06, 2011, 07:34:05 pm »


What it has been used for has no bearing on whether it actually carries an engineering rating for overhead suspension.  I was told by an engineer on a project that it does not and, I can't find a rating listed anywhere.  What makes it rated when used in construction is a set of drawings being signed off on (and stamped) by a structural engineer and the construction then following the drawings. 
Even if individual pieces carried an overhead suspension rating you could not build them into a system and have it be rated for overhead suspension unless that exact system also carried a rating.  It's the same as speaker rigging.  I can buy overhead suspension rated components and build them into my home-made speakers (or store bought speakers with no rigging provision) but, unless the system is rated as a whole, my speakers are not rated for overhead suspension despite my using rated components.

I may be wrong on Unistrut not carrying an overhead suspension rating, please inform me as to the rating and the rating standard if it exists and stop telling me what it's been used for.

You are correct that "It is done everyday."  I was just pointing out that it may not carry a proper rating once this was done which could have an impact if there were a future problem.  People put their own "rigging" in speakers everyday also, it does not make it safe or something that will be O.K. with an insurance company if there is a problem.

Lee Buckalew
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Quote
What makes it rated when used in construction is a set of drawings being signed off on (and stamped) by a structural engineer and the construction then following the drawings

The above is what makes ANY system flown in the air a "rated" system/structure.  What you (and your engineer friend) seems to be missing is that there is no governing body for rigging in the United states that stamps "Rated for overhead use" on items. There is no magical "Engineers rating".  While there are ratings and standards from many different segments like materials (think grades of bolts that must comply to a standard or steel must comply to a hardness standard), and there are organizations like ESTA that are trying to standardize rigging practices, there is no magical rating stamp your engineer alludes to.

This "overhead use rating" is done by manufacturers themselves  by testing their components in many different ways including until they break. It also includes tracking raw materials, monitoring the manufacturing process closely, and putting ID numbers on items or lot batches to be able to track them after the sale. They could do this testing inhouse, or send it off to an outside entity.

A perfect example is a wooden roof truss. 2x4s themselves have general weight loading guidelines based on length and species of wood. They also do not have a "Rated for overhead use" sticker anywhere on them. BUT, if you look up in most homes today, 2X4s are a part of the ROOF TRUSS system, and as a part of the completed assembly, they become acceptable for overhead use.

Another good example is Grade 8 bolts. Most truss manufacturers state that Grade 8 bolts should be used to join their sections of truss together. This is in part because when they did their destructive testing and weight loading, those were the grade of bolts used, and by speccing an item with known load data, they have a constant in the system.  But, I have never seen a bolt stamped "Overhead Use" on it.

Many manufacturers (especially those who make specific rigging fitting for speakers and such) use the words "rated for overhead use". But, a lot of them also do not.  For example, show me on Applied's website where is shows that their 12X12 truss is "rated for overhead use".  I couldn't find words to that effect on any of the specs or advertising on their 12X12 truss.   I did however find load ratings including UDLs and Center point loads (implying that you would hang something from the truss) as well as warning like "Do Not Load Top Chord Of Truss Without Contacting Engineer For Approval." but the closest I came to seeing  something that said I could put the truss up in the air was the following:

"All Purpose truss, combined with the matching corner blocks, can be used to construct a grid." 

Same with Unistrut. I saw where they track their materials, how they conform to the
"AISI spec of Cold Steel Formed Structural 2001 edition", how they do destructive and non destructive testing,  and how they stamp tracking numbers into the products. In addition they use terms like "you can design any system withing the capabilities of the components" and "grid", and support system, etc.  I even saw examples of the product in their catalogs used overhead and in one description I read that the "nut provides easy overhead installation with one hand". 

So I guess technically your engineer friend is correct, Unistrut does not use the wording "rated for overhead use", BUT neither does Applied Trussing.

If there was an accident or failure of a wooden roof truss, a metal Applied truss, or Unistut, I'm sure a lawyer trying to get a large settlement for their client would point out that these 3 items are not "Rated for overhead use". But, the opposing lawyer could just as easily point out that those words have no meaning since they are basically "self titled" by the manufacture itself, and not a rating from a single industry wide governing / certifying body. And in fact that all 3 items have been highly tested and have known load limits and were indeed used in accordance to the manufacturers intent.

I suspect that many manufacturers do not state the "Rated for overhead suspension" wording because their lawyers told them not to.  And since there is no standard governing body for testing or rating theatrical rigging, they do not need to submit their items to an outside source for testing.

The fact that Unistrut is used in almost every commercial building, as well as used as a rigging fitting in Las Vegas (one of the most stringent code areas known to any commercial building) shows that your engineer friend is in disagreement with 99.9% of the rest of the folks in the construction and entertainment industries.




« Last Edit: April 06, 2011, 11:20:23 pm by Craig Leerman »
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Len Woelfel

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Re: Hanging fixture from uni-strut
« Reply #8 on: April 06, 2011, 07:54:35 pm »

Here is a page from the Unistrut website showing horizontal and vertical loading. For example, a horizontal 1 1/4" track 48" long supported at both ends can support a Uniform Distributed Load (UDL) of 360 pounds. 

http://www.unistrut.us/index.php?WP=cat_detail&S=S05&P=A1000

Craig

Thanks for the link reminder.  You saved me looking for it.
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Lee Buckalew

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Re: Hanging fixture from uni-strut
« Reply #9 on: April 08, 2011, 07:25:39 am »

The above is what makes ANY system flown in the air a "rated" system/structure.  What you (and your engineer friend) seems to be missing is that there is no governing body for rigging in the United states that stamps "Rated for overhead use" on items. There is no magical "Engineers rating".  While there are ratings and standards from many different segments like materials (think grades of bolts that must comply to a standard or steel must comply to a hardness standard), and there are organizations like ESTA that are trying to standardize rigging practices, there is no magical rating stamp your engineer alludes to.

A perfect example is a wooden roof truss. 2x4s themselves have general weight loading guidelines based on length and species of wood. They also do not have a "Rated for overhead use" sticker anywhere on them. BUT, if you look up in most homes today, 2X4s are a part of the ROOF TRUSS system, and as a part of the completed assembly, they become acceptable for overhead use.

Same with Unistrut. I saw where they track their materials, how they conform to the
"AISI spec of Cold Steel Formed Structural 2001 edition", how they do destructive and non destructive testing,  and how they stamp tracking numbers into the products. In addition they use terms like "you can design any system withing the capabilities of the components" and "grid", and support system, etc.  I even saw examples of the product in their catalogs used overhead and in one description I read that the "nut provides easy overhead installation with one hand". 

So I guess technically your engineer friend is correct, Unistrut does not use the wording "rated for overhead use", BUT neither does Applied Trussing.

If there was an accident or failure of a wooden roof truss, a metal Applied truss, or Unistut, I'm sure a lawyer trying to get a large settlement for their client would point out that these 3 items are not "Rated for overhead use". But, the opposing lawyer could just as easily point out that those words have no meaning since they are basically "self titled" by the manufacture itself, and not a rating from a single industry wide governing / certifying body. And in fact that all 3 items have been highly tested and have known load limits and were indeed used in accordance to the manufacturers intent.

The fact that Unistrut is used in almost every commercial building, as well as used as a rigging fitting in Las Vegas (one of the most stringent code areas known to any commercial building) shows that your engineer friend is in disagreement with 99.9% of the rest of the folks in the construction and entertainment industries.


Sorry to have caused such a commotion.
My comment was valid and accurate and you refute yourself within your post.

What makes a system rated, in the U.S. is an engineer having reviewed the design layout, including what components will be used and how they will be interconnected, and signing off on it and stamping it.  I never said stamping it for overhead use.  A structural engineer would use their engineering stamp to certify a drawing or written description.

This system is far more flexible than preset standards as it leaves leeway for the engineers to decide if a use is O.K. 

As far as attorney's going for "a large settlement for their client...".  If an engineer did not review it then the person or company doing the installation assumes the liability, no question.  I have often seen, in the field, proposed solutions that would not have been acceptable and, once run by the engineers, a correct solution was made.  In some instances, due to time and/or financial restraints, changes are made that cause problems.  Same components but different layout can equal death and maiming.  We had a multi-level skywalk between buildings collapse in Kansas City a number of years ago because an onsite change was made due to scheduling and parts arrival.  Long lengths of threaded rod were not available, short lengths were used instead and applied in a manner that caused structural failure years later. 

Was I trying to say, don't use Unistrut for the proposed little project, no.  Just pointing out an engineering truth.

Lee Buckalew
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Re: Hanging fixture from uni-strut
« Reply #9 on: April 08, 2011, 07:25:39 am »


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