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Rental Gear Wiring

Discussion in 'Lighting and Electrics' started by lightbyfire, Dec 6, 2007.

  1. lightbyfire

    lightbyfire Member

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    So this should show how valuable it is to at leasat be able to recognize that something is "not right" even if unable to actually fix the problem.


    So we rented some 5K Arri Fresnels from a local company. We load in and hook them up to 6K dimmers that had never been used before. One works the other doesn't, we check the breaker, all good, and getting signal. Check the lamp, looks fine, tests continuity. So then i test continuity on the 60 amp stage pin and find the ground and neutral reversed, as in it was reading as though it was wired like a 20 Amp would be wired (continuity was from the two farthest pins). So I double checked last night to make sure I was right that 60 amp are wired backwards, and today i take it apart only to find that the wires are in the right configuration (ground farthest from stand alone hot)

    So we called the rental company and they suggested we track down the problem, so I looked into the switch box on the side of the unit and find that the ground has been tied to the neutral pole of the switch, and the neutral from the tail is connected to the ground screw. Not only that, but it would appear from the length of the conductors and the wear on the ring crimps that this had been this way for some time. Perhaps the neutral and ground had been reversed at the male end of the tail and only in the last inspection in the shop had somone switched it back. In either case, had the hot shorted to the fixture casing, we would not have tripped the breaker but instead created a completed circuit!


    Always check continuity on rental gear, you may find more than just blown lamps. And if something doesn't seem right, well it probably isn't.


    By the way, we are not going to fix it ourselves and have decided to return it and go with only one 5K for the production, they were overkill anyway.
    Here are some pictures from inside the switch box, notice the reversed neutral and ground.
     

    Attached Files:

  2. Van

    Van CBMod CB Mods Premium Member

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    Wow! Good catch. It's amazing what some people do. :rolleyes:
     
  3. dj_illusions

    dj_illusions Active Member

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    In Australia, well Victoria at least it is legislated that any hire company, especially theatrical hire must test and tag any electrical appliance before it goes on hire, this includes doing an earth bond test and resistance test on the appliance to ensure all is in correct order.
     
  4. Logos

    Logos Well-Known Member

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    Pretty much universal in all of Aus. the rules simply vary over who can do said test.
     
  5. dj_illusions

    dj_illusions Active Member

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    ah that is good too know....

    i am one of the fortunate ones who is qualified to push 'go' on the test machine, yay for me... not!

    I cant believe I sat through an 8hour class to learn that you shouldnt plug something in when the active and neutral are around the wrong way or the cable has a nick in it, and you should run it on the test machine to make sure... hmmm
     
  6. Logos

    Logos Well-Known Member

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    In SA any "responsible person" can do the test. Despite *mumble* years in the business I decided that the easiest way of becoming a "responsible person" was to do the course so I did. (My wife incidently thought it was hilarious that I was getting a certificate that was making me a responsible person, she thinks it would take major surgery and several years with a councellor to make me responsible.)
     

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