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Safety Cables...

Discussion in 'Lighting and Electrics' started by muvment, May 30, 2008.

  1. muvment

    muvment Active Member

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    What is the cheapest way to buy 50-100 safety cables? I have a client that is desperately in need of cables for every fixture in the house and has a tight budget.
     
  2. avkid

    avkid Not a New User Fight Leukemia

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    Call your local lighting dealer and ask for their best quantity price, then talk them down a few percent.;)
     
  3. JD

    JD Well-Known Member

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    The on-line supply houses usually have pretty good deals, but I question the words "Cheapest" and "Safety" being in the same sentence ;)
     
  4. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Last edited: May 30, 2008
  5. avkid

    avkid Not a New User Fight Leukemia

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    Which you shouldn't be doing anyway, unless you have the right tools, knowledge and are willing to accept the risk associated with the use of the device.
     
  6. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    And once the theatre has them, take apart one side of the yoke to fixture-body attachment, and slip the loop end around the yoke. Never again will a fixture not have a safety.
     
  7. porkchop

    porkchop Well-Known Member

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    1. It is a good way to keep all of your units safetied
    2. I hate it when people do this cause the clip is never in a convenient place
     
  8. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Care to expound? The clip is always within 30" of the yoke. Do you find the fixture's connector "never in a convenient place" also?

    The only time I dislike the practice is when packing rental lights--one more thing to catch on when un-boxing/boxing. Still, if it's there, I find people will be less apt to forget to use it.
     
  9. Sean

    Sean Active Member

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    I'm confused as well. How is the clip in a non-convenient place? If anything, putting the loop on the yoke makes it EASIER to safety the light--you gain a couple inches as you don't have to choke the safety to the light (when making a long reach).

    --Sean
     
  10. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    I like them on the yokes. It does indeed give you a few inches. Really I find the most inconvenient thing is on the integral safety point. The integral point can really make getting focus a pain, thus I hardly use it.

    Now, what I want to know, is must the carabiner always be clipped t the loop on the end of the cable, or is it acceptable to clip the carabiner to the cable itself, so its in the shape of a nine. Say you have the loop of the cable attached to the yoke. Then, you just wrap the other end around the pipe and clip it to itself. Does that make sense?
     
  11. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    My feeling is that you should always make the distance of the potential drop as short as possible before the safety catches. If the clamp fails the shock load on the cable will be less if the instrument has a short distance to travel before the safety kicks in. In order to do that sometimes it's easier to loop back to the loop on the other end of the cable and sometimes it's easier to loop around the bar a few times and connect right to the cable itself.

    I'm sure that Uncle Bill or Jay Glerum could give us the math to show one way of connecting the safety is better than the other. However, it seems like the difference would be minimal as long as it's a properly built cable.
     
  12. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    One of my biggest pet peeves is teaching lighting hands not to double wrap the safety around the pipe and yoke, as it limits the amount of pan. For non-permanently attached safeties, I prefer a figure-8 type pattern, with the clip into the loop.

    Yes the question makes sense; but, no it's not desirable. Too much chance of side-loading the "Carbine Snap 316 Stainless with Eyelet". With a standard theatrical C-clamp, the yoke is 4.25" below the center of the pipe, which should leave one plenty of length to clip back to the loop, even with a wrap around the pipe. If a tail-down or side-arm, use multiple safeties if necessary, but again, try to avoid side-loading the clip.
     
  13. Charc

    Charc Well-Known Member

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    I don't follow, can you please clarify what you would say the appropriate method is?
     
  14. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    "Can" indicates ability; "May" indicates permission; "Will" indicates a future event.

    So I WILL elaborate, but I'm not sure it will lead to clarification, as I haven't figured out that fancy 3D Google Sketch-Up yet.;)

    For conventional fixtures only: Take a safety and approach an already hanging, finger tight fixture. Put either end of the safety under the yoke, near the yoke bolt, centering the 30" cable with the yoke. Cross the ends of the safety between the top of the yoke and the bottom of the pipe. Clip the Carbine into the loop above the pipe. When viewed from the side, one has made a Figure-8, although the "lay" of the aircraft cable will make the safety want to lay down on the pipe. Wrench tighten the C-clamp bolt 1/4-1/2 turn. This method has the advantage of keeping the safety of out the way, but still allowing the fixture to pan more than 360° if necessary.

    I find that just looping the cable under the yoke and over the pipe, then clipping to itself tends to get itself in the way, and often jams in the tilt-lock mechanism, between the yoke and fixture body.

    As for the math involving the force of a falling object (Newton's Second Law), let's assume we're talking about your favorite Altman 1KL6-20. Altman's cut sheets say it weighs 25 lbs. Using an Altman cast-iron C-clamp, the bottom of the yoke is 5.5" from the top of the pipe. The 30" safety, looped, is 15", so the most the fixture can fall is 9.5". A 25 lb. object falling 9.5" [in a vacuum, due to acceleration due to gravity (23.174ft./sec.^2)] generates a force of 87.4 lbs. Using a 5:1 safety factor, your safety-cable-assembly must have a minimum breaking strength of 437 lbs.

    I knew 8th grade science would come in handy one day.:rolleyes: Clear as mud?
     
  15. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    I would say the most important thing is to make the distance the instrument will fall before the cable catches it as short as possible. If the instrument has to drop 20" before the cable grabs it, that's a lot more force and therefore the chance of failure is much greater than only dropping 2" or 3". You can see using Derek's math its much better if that instrument only falls 1/4 of a second than if it falls 2 seconds.

    Beyond that I think there is a lot of personal choice and style involved.
    I teach:
    -hang the instrument and finger tighten.
    -Loosely wrap the safety cable.
    -1/2 turn on the c-wrench to lock it down.
    -focus
    -Reposition/wrap the safety cable to minimize fall distance.

    My feeling is as long as you are using good cables in good condition how it is connected doesn't really matter as long as the distance is short and it isn't hanging in a way that could potentially put a side load on the clip.

    Also note Selecon safety cables don't use the snap hooks like the U.S. manufacturers they use biners with a threaded nut that secures it locked sort of like this:
    [​IMG]
    or they use quick links. Both products are much safer because you don't have the potential of the snap failing due to the side load.
     
    Last edited: May 31, 2008
  16. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Re-safety after focus???

    And both styles take longer than a self-closing clip.

    I think our differences in philosophies stem from "educational" vs. "professional". You have free/volunteer student labor, whereas I have a man (or woman) walking a truss, being paid "high time", and am trying to avoid meal-penalty and OT.

    It took me sixty minutes to call the focus of six SixBars of S4-PARs of backlight on a 60' truss last week (I had a slow climber), just one pass across. On the other hand, the FOH truss, focused from a boom lift, with the same amount of lights took around 25-30 minutes, including swapping out a bad Soca tufer. I've usually contended that truss climbing was faster than a lift, but not in this case.

    Agree to disagree?
     
  17. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    So I've been doing these corporate gigs, which are, of course, "all about the out".

    About half the people in town think thats its faster to never unclip the safety on the load in, but rather to just wrap the pipe with the safety and to then clip it back to itself. (See crappy picture for details). Sure, faster on the in, but on the out it takes longer to wrangle the two sides of the safety cable out of the clip than it does to just unclip and then reclip.

    safety.jpg
     
  18. DuckJordan

    DuckJordan Well-Known Member

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    Doesnt matter
    And was the lift brought in each time or was it a drivable lift?
     
  19. hobbsies

    hobbsies Active Member

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    My personal pet peeve is when the safety is passed through the yoke on the side of the tilt handle. If you take a c clamp off, make sure the safety stays on the side of the instrument without the tilt handle (source fours mostly here).

    Derek, your figure 8 style is interesting, but isn't that similar to just wrapping the pipe twice? It still gets tangled up if you spin the light 180.
     
  20. techieman33

    techieman33 Well-Known Member

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    I always wrap the safety cable around the fixture body when not in use, it's a lot less likely to snag on something coming out of a box or off of a meat rack.
     

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