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Hanging Iron / Gridwork

Discussion in 'Lighting and Electrics' started by jonliles, May 11, 2009.

  1. jonliles

    jonliles Active Member Fight Leukemia

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    Guys-
    I need to take to the board the necessray governing documents regarding gridwork and materials. Currently, the "grid" is made of conduit vs sched 40 Black Iron pipe. I won't go into details of what is holding the conduit in the overhead.
     
  2. icewolf08

    icewolf08 CBMod CB Mods

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    As rigging is one of those topics on CB that falls under the "If you have to ask then you shouldn't be doing" category, I would recommend that you get in touch with your local theatre supplier or a theatre consultant or a professional rigger. You can search for local ETCP Certified riggers here.

    Needless to say, if your grid is made from questionable materials with questionable rigging, then you should stop using it immediately and get it inspected.
     
  3. jonliles

    jonliles Active Member Fight Leukemia

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    No code I can reference?
     
  4. icewolf08

    icewolf08 CBMod CB Mods

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    If there is a written code, I am not familiar with it, however, I am not a certified rigger. I would suggest calling someone like "Uncle" Bill Sapsis at Sapsis Rigging. Or if your local supplier does rigging installs, they would probably know as well. Your other option may be to try sending a PM to [user]what rigger?[/user] who may be able to help you outside of the forums.
     
  5. jonliles

    jonliles Active Member Fight Leukemia

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    Thanks for the leads!
     
  6. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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  7. FatherMurphy

    FatherMurphy Active Member

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    You could also approach it from the direction of a structural engineer, but the rigging contractor folks are probably a better place to start. The riggers are more likely to be able to come out, do a fairly quick visual survey, and write a nicely frightening report for the school board. A structural engineer could write an equally frightening report, but would need to do a bunch of measuring and calculating first, at a correspondingly higher cost.

    Don't be surprised, though, if one of the rigger's suggestions is getting an engineer involved to figure what the structure can support.
     
  8. Footer

    Footer Senior Team Senior Team Premium Member

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    I sent the OP a few PM's about who to deal with in the district, the school in question is in my district. We have the lots of schools and very little over site syndrome in the district. We have 13 high schools all with theatres and all with varying degrees of maintenance. My theatre was completely re-rigged 3 years ago due to conduit used as battens and chain I would not put on a swingset holding up battens. Oh, and a load bearing dog collar. I just run my 2 theatres, and I am the only person employed out of the 15,000 employees that is actually trained in theatre operation.
     
    jonliles and (deleted member) like this.
  9. gordonmcleod

    gordonmcleod Active Member

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    Conduit grids in cable studios and schools are fairly common up here and most were designed by engineering firms with a rated load per foot specified
    most were hung on threaded rod from ceiling Ibeams and were calculated as part of the buildings structural load
     
  10. jonliles

    jonliles Active Member Fight Leukemia

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    long story short- I am a mechanical (nuclear physics focused) engineer. I understand structurual loads - it's one of the first classes in vector mechanics (AKA Statics).

    Conduit scares me for many reasons. One of which is that it is easily deformed - especially by C-clamps to the point of crushing and distorting the conduit. That deformity creates a weak spot which sooner or later the laws of physics take over and that conduit will break at the point of deformity. I've seen it many times in power plants all over the globe

    From a construction standpoint, conduit is not loaded rate. It is not mean to support anything on the outside other than it's own weight. Conduit is meant to contain wire runs. A couple of extruded aluminium par cans would be OK, but think on the weigh when you start adding in various vintages of ERSs. Think how much the old Altman 1K's weigh , or even the 360Q's and their lenses.

    Thusly, I want the theatre to pony up, an put in something correct - sans jack chain.

    Thanks all for the input.
     
  11. TimMiller

    TimMiller Well-Known Member

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    Aluminum fencepost is stronger than conduit, they should at least use that :rolleyes:
     
  12. ship

    ship Senior Team Emeritus Premium Member

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    No they should not. None of the above is proper though 1.1/2" Sch. 40 is the norm or old standard yet also not rated for the purpose. Anyone mention Batten Pipe - what's designed for the purpose? This in not going into detail as we are all on the borderline of what's too detailed about rigging to discuss or recommend.
     
  13. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Last edited: May 15, 2009
  14. TimMiller

    TimMiller Well-Known Member

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    just encase no one got the sarcasm, I WAS KIDDING. CONDUIT AND FENCEPOST SHOULD NOT BE USED FOR RIGGING UNDER ANY CIRCUMSTANCES. Schedule 40 pipe should be used at the least.
     
  15. reggie98

    reggie98 Member

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    Are you sure that you aren't mistaking speedrail (sched 40 aluminum pipe) for conduit? And what kind of conduit? EMT, IMC or ridgid?
     
  16. kmontagne

    kmontagne Member

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    Does anybody know of a reference that specifies load limits for different spans of schedule 40/80 pipes of various sizes?
     
  17. LightStud

    LightStud Active Member

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    Something other than the attachment in post#13 above?
     
  18. kmontagne

    kmontagne Member

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    You are right. I missed the 2nd attachment in that message. I will pay more attention next time.
     
  19. teqniqal

    teqniqal Well-Known Member

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  20. TimMiller

    TimMiller Well-Known Member

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    reggie is right, speedrail looks just like EMT, but it is sch 40 alum pipe. It is used all the time in lighting grids, especially the video and film industry. It is some great stuff. If you can safely take a piece of it down, you will know what it is. If its about 1/4" thick its definately speed rail. Speed rail is attached using fittings that have several allen screws.
     

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