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Power Tap Horror Stories

Discussion in 'Lighting and Electrics' started by JD, Apr 11, 2008.

  1. JD

    JD Well-Known Member

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    Location:
    North Wales PA
    Winner:
    Academy of Music, Philadelphia 1982: Watching as my roadie dumps a coil or 4/0 down a stage hatch and hearing the scream from the person whom it landed on below deck; The Union Electrical Chief. Cost me a lot of humble pie, and ended the career of one roadie. (He was officially banned from the theater.)

    Second Place:
    1976: Wading through two feet of water in a flooded basement near freezing (It was an old Ski Lodge) and having to do the tap while standing on a beer compressor to stay dry. In the middle of said operation, the compressor started up!

    Runner up:
    Watching a house electrician bug my white camlock tail onto one of the hots and trying to figure out how to tell the guy (who had quite an attitude) that what he was doing was wrong!
     
  2. STEVETERRY

    STEVETERRY Well-Known Member

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    My favorite disaster:
    The Tony Awards at the Shubert Theatre, NYC 1977.
    A big pile of 24 pieces of 4/0 is fed over the rung of a vertical steel ladder with a 30' drop. The lower conductors get crushed, short to the ladder, and a big boom and roar (truly frightening) and major sparks with big chunks of flying molten metal occur. Guys are running for shelter. And this keeps on going for many. many minutes. Why? The disconnect is 700 feet down the street in a Con Ed manhole. And a 700 foot run of 4/0 will supply 399 amps into a dead short without tripping the breaker, for a very, very long time
    Moral of the story: have a disconnect close at hand, with the proper coordinated overcurrent protection.
    Moral #2: provide proper stain relief for feeders.
    Moral #3: It was the one time in my career I was truly glad to be the sound guy.
    ST
     
  3. Charc

    Charc Well-Known Member

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    Er. Wow, ST. I can only imagine having to run 700' to a manhole in that sorta situation.
     
  4. JD

    JD Well-Known Member

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    Ha! That reminds me of the Roxie Theater up above Allentown PA. (Again, the 70's) There was this large disconnect that had a feed that looped below the stage and into a tunnel. (Crawlway would be more accurate.) Anyway, I always wondered where it went, so one day when I had some spare time, I crawled in. The tunnel looked like one of these things you see on the news where drugs are smuggled from Mexico. It went on and on, and I was sure I was no longer under the theater. Finally, it ended, in the basement of a drug store that was down the block! (Always wondered what type of arrangement (if any) was going on there!)
     
  5. porkchop

    porkchop Well-Known Member

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    Mines not quite as exciting. I was doing a county fair 90 minutes drive from home. First they give us like a 10kW generator for the whole show and we (me and the sound guy who was supposed to be the expert on the hook up....more on that later) just look at the guy with a "do you really think that'll work" look. We finally get a genny that'll power the show and the "expert" proceeds to do the ugliest most chicken s*** hook up I've ever seen that was in effect little more than twisting the wire for the tails with output wires from the genny together and wrapping them in electrical tape. At about the 4th tail he realizes that he hasn't paid attention to the color of the cam lock on the tails but we're late already cause they got the genny wrong the first time so he doesn't see it necessary to go back and fix it. Long story short I ended up blowing the dimmer rack, going through $10 in fuses, shocking the crap out of myself, and ended up running the show out of wall sockets just hot plugging the lights I needed.
     
  6. Charc

    Charc Well-Known Member

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    So the chicken-s***-ness of the hookup was just due to the way he tied into the bare ends?
     
  7. Sean

    Sean Active Member

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    ALWAYS METER YOUR POWER. I don't care what the house guy said/says he did--meter it yourself.

    --Sean
     
  8. JD

    JD Well-Known Member

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    Yep. Right there in my first post. I WATCHED a so-called "house electrician" bug my neutral to a hot! If that had been out of view, and I didn't have meters on my distro, or didn't meter it, then there would have been trouble! Heck, I even meter my own tie-ins ;) No one is perfect, yet that is one job that requires perfection.

    Since I'm using up posting space, might as well throw in another off my top ten list:

    Show up at a club called "The Playpen" in Wildwood. (no longer there) So, our crew is the only ones there and we have a four hour setup. Out back, a pad and a 13.2kv disconnect. Inside, an pre-WWII "cage of death" to tie into. So, I dropped the 13.2kv... yea... rest of the story is in my by-line below.
     
  9. tgates

    tgates Member

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    The worst one I was partially involved with happened while a dimmer rack of ours was on a sub rental. The client before had apparently had trouble either getting on or taking off the cam from the output side of the feed through. So CUT OFF THE FIRST INCH OF INSULATOR around the female cam. Seeing as we have those safety covers on all of the cam outputs, nobody saw it, and of course the previous renter never bothered to mark it, much less tell us. You can of course imagine the effects of a 200 amp service being dead shorted to the metal cover. That is, before the cover literally blew off the front of the rack.

    The other story, which I've only heard, was at my last place of employment. They had someone close a metal wheeled, multi-ton aircraft hanger door rolled across a run of 4/0 while it was hot. Somehow the breaker wasn't blown despite the genny being so overloaded, rocking from side to side on it's trailer from being so out of balance.

    It could have been a steam tunnel, back from the days when buildings got their heat from a central steam plant elsewhere in the neighborhood. Actually, I've heard this is still common in many big urban areas for both cooling and heating, but simply use buried pipe rather then a tunnel from building to building.
     
  10. bdkdesigns

    bdkdesigns Active Member Fight Leukemia

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    We still have steam tunnels here. In fact this year they worked on refurbishing them.
     
  11. JD

    JD Well-Known Member

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    Steam pipes creep me out more than electrical lines! Usually, you have to be interacting with electricity to get killed. With steam, you just have to be in the wrong place at the wrong time. (Now transformers are a different story! If you hear a boiling sound in one... Run!)
     
  12. Dustincoc

    Dustincoc Active Member

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    I hope they aren't used if they've got electric lines running through them.:(
     
  13. porkchop

    porkchop Well-Known Member

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    A lesson I learned the hard was, next show I did have 3 huge genny's and I did the tie in. I had a guy working with me meter while I watched just to make sure that it wasn't done wrong.
     
  14. photoatdv

    photoatdv Active Member

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    Quick question: My hs has a 3-phase aux. power box for when we rent MLs. I recently noticed that power is on to it. Should power be off when it's not being used? To the best of my knowledge it won't be used for several months.
     
  15. MNicolai

    MNicolai Well-Known Member Fight Leukemia

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    Bone Collector anyone?
     
  16. JD

    JD Well-Known Member

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    If its a passive distribution box and everything is properly capped (no live cam tails) then it doesn't really matter. I would probably turn it off myself. (One less thing for people to mess around with and leave in an unsafe condition.)
     
  17. len

    len Well-Known Member

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    They sometimes do. They shouldn't, but they do.

    There are lots of tunnels in Chicago. Some were built/used during prohibition to move liquor and people. The older theaters (Aragon, Congress, Uptown, etc.) have them. Most are sealed up. Some are in use as storage.

    The ones downtown used to have a narrow gauge electric train running through it, which was used to deliver coal and goods to the stores. A utility worker broke through one in about 1992 and flooded most of downtown. It was quite a little disaster.
     
  18. Van

    Van CBMod CB Mods Premium Member

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    Occupation:
    Project Manager, Stagecraft Industries, Inc.
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    Portland, Or.
    Mines a disconnect story;
    A kid working on an out of a music festival. Trying to be helpful walks over to the EDI 48 roll-around rack and starts pulling the cams. She's new, she knows you connect G,G,W,Bl,R,B, so she fugures you disconnect the same way. Oh did I forget to mention the backstage works were still on, on two of the dims?
     
  19. FMEng

    FMEng Well-Known Member Fight Leukemia

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    There are a couple of things to understand about why the breaker did not trip. The first is that generators are often inherently current limited by their voltage regulator and excitation circuit. That is, they will only produce so much current into a dead short.

    The second is that no circuit breaker trips instantaneously, and the time it takes inversly proportion to the load current. When the current is ten times the breaker rating, it may take one second to react. When the current is only twice the rating, it can take a minute or more to trip. Right at the rating, it might take hours to trip.

    In your case, the generator limited the current to an amount that took the breaker some time to react to, and someone shut it down before it would have tripped.
     

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