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A small box with a BIG problem...

Discussion in 'Safety' started by sloop, Nov 14, 2007.

  1. sloop

    sloop Member

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    We have an outdoor stage that occasionally floods. It is seldom used but the students decided they would like to use it more. With the flooding, the electric supply was sketchy at best.

    We decided a portable system was needed. We purchased a Lunchbox-- 5 20 amp outlets and a mogul 3 pin stage plug(bates plug) rated at 100 amp.

    We put a 100' of JSO cable and a waterproof connector at the power panel.

    So, we have 100 amp 100' extension cord, or so I assumed....

    It turns out the electrician didn't understand we were running a 100amp single phase extension cord. He wired it up as 2 phase 208... 2 hots and a neutral...

    As a test, he plugged his work light into it and it worked fine.. I didn't think anything about it--he was an electrician.

    The band shows up, plugs in and BOOM there goes there amps.. I get my meter out and check things. It is immediately apparent what had happened. In 5 minutes I had the panel re-wired and we were up and running. No one was hurt, but NEVER assume a job is done right... check it out yourself!!
     
  2. mbenonis

    mbenonis Wireless Guy Administrator Premium Member

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    This is why one ALWAYS uses their voltmeter to check voltages before plugging anything in at a show. Never assume things are wired correctly, hooked up correctly, or functioning correctly, until proven otherwise.
     
  3. sloop

    sloop Member

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    the sad thing is, generally I do. I generally check, especially on new install stuff, but knowing the electrician it didn't even occur to me.
     
  4. Van

    Van CBMod CB Mods Premium Member

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    Is it all GFCI'd as well? I used to work in an Outdoor theatre. It amazes me that we never fried anyone during the Ocassional downpour. I had to redo all the conduit around the edge of the stage one year, it was scary. Lots of loose conduit, worn out insulation this was in the days before gfci was available. Perhaps adding little legs to that Lunchbox would be a good idea, turn it into a spiderbox.
     
  5. fosstech

    fosstech Active Member

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    Now I wonder why his work light didn't blow a lamp at 208V.

    If he wired it that way I'd question his electrician credentials. Standard 3 wire 208v runs are supposed to be two hots and a ground.
     
  6. sloop

    sloop Member

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    Yep, fully GFI'd..
     
  7. sloop

    sloop Member

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    Well the ground and neutrals are bonded so it was.. It was a fluorescent light too, you would have thought the ballast would have instantly fried..

    I think he "assumed" the breaker that was there and empty was the breaker for the unit. More assumptions... they piled up and bit us in the ass..
     
  8. miriam

    miriam Active Member

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    What exactly happened when the amps went boom? Was it just very loud, or did something break that you replaced? It sounds like you changed how things were plugged in??? And how did you know that was definitely the problem and not a different part of the setup?

    Thanks.
     
  9. icewolf08

    icewolf08 CBMod CB Mods

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    He knows that the power distro was wired wrong because in the US, the voltage between hot and neutral should be between 110v and 130v. Sloop told us that he metered the voltage at around 208v which suggests that he had two hot legs coming in like a split phase system.

    When the amps got fried, it is quite possible that there was a loud noise from it, and at the very least it would blow the fuses, but the over voltage has the potential to destroy some of the electronics as well.

    In the US, you should never have a 208v source that has an "Edison" or PBU, or stage pin connector. This is of course so that things like this don't happen. It sounds like your electrician had stuck his tongue in a few too many outlets.
     
  10. sloop

    sloop Member

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    Actually, it was just a small pop.. Probably just the internal fuses blown, but it might have been the power transistors.. Either case the University is going to pay for replacement/repair.

    What I fixed was the the way it was wired at the power panel. I pulled the what should have been the neutral leg out of the breaker, tied it to the neutral bus. The ground was already on the ground bus. After that--it was wired the way it was supposed to be....

    It only took a glance in the power panel to see the error....
     
  11. miriam

    miriam Active Member

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    So knowing wiring sounds extremely important. How do you practise, though? If a person took old cables that don't work so well and switched wiring around in the plugs, (maybe also switching plugs?) until it felt comfortable to do in five minutes, would that be a worthwhile thing to do?

    But if the cable doesn't work so well, how to test it? Hmmm.
     
  12. icewolf08

    icewolf08 CBMod CB Mods

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    Find someone to teach you how to correctly wire cables before you go and practice. Seeing as I doubt that anyone on this forum is familiar with Israeli standards, and we are not supposed to give such instruction on this forum. Also, if you primary interest is in sound you should have someone teach you how to solder as well, because you will ned that when you start fixing XLR and 1/4" cables.

    Other than that, it certainly is a lot safer to practice on cables that aren't being used. Testing cable is easy, you just need a good multi meter that has a continuity test feature, or a GamCheck (pictured below). Both work on the same principle. With the GamCheck, you would plug both end of the cable into the tester and then it sends a little 9v down the cable and lights up if it is wired correctly. A multi meter will do the same, though it can only test one conductor at a time and they usually make a nice annoying beep.

    [​IMG]
     
  13. sloop

    sloop Member

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    Yes, knowing wiring is very important. Not something to be taught via a message board. I agree with Icewolf.. Gamchecks are GREAT! not only will they tell you if cables are bad, they will check lamps and circuits too.

    I have seen a lot people "guess" what is wrong when a lighting instrument won't work. I pull out my Gamcheck so I know what is wrong.
     
  14. miriam

    miriam Active Member

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    okay. In class we learned about wiring and cross wiring, and inspected different types. But we did not actually do it ourselves. I suspect a more avanced class in sound would teach that.
    Thank you for the heads up, I will only attempt it under qualified supervision.:mrgreen:
     
  15. Charc

    Charc Well-Known Member

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    Er, I've more or less learned wiring from the internet. Which reminds me, I need to take some cables out of the air, as I have a sneaking suspicion (5% probability) that I switched the hot and neutral on a cable or two. With incandescents, it doesn't matter. But if anyone plans to hookup anything else, I wanna make sure it's right. Luckily I have a gamchek.

    (It's not my fault! If my **** school followed NEC if the first place I'd know what was going on, instead? 3 White 12GA wires. Don't tell me it's all neutral!)

    We have no crimper or crimp connectors, so I've pulled the ol' "Bend the wire in a U shape, clockwise around the screw." Technique. We also have no soldering iron or solder. I have a soldering iron or solder, but I've learned what happens when you will get "reimbursed by the school" so they can buy their own crap. (One faculty member approves all purchases and guarantees reimbursement, only to turnaround and say "can't come out of my budget, talk to X" so yea, that's what happens when your budget is split into thirds.) Also, we have a few of some weird type of connectors that require nothing beyond screwing down on the wire itself... weird. (I need to take a brief look at my electronics book for some more terminology, it escapes me these days.)
     
  16. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    If you are doing sound don't forget the Swizz Army Tester...

    [​IMG]
     
  17. icewolf08

    icewolf08 CBMod CB Mods

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    Once again, charc proves why he should be supervised... Don't blow yourself up!
     
  18. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    A word of caution Charc: a GAMcheck (or VOM) WON'T tell you if you've mixed up hot and neutral at BOTH ends, so be sure to get a visual on ALL terminations of the cables you suspect you may have wired wrongly.

    As long as we're on the subject:

    For Stage Pin (2P&G, Bates plug):
    Green (Ground) in the middle
    Black (Hot) to the pin farthest away from the others
    White (Neutral) to the other pin
    [Currently looking at a Union-Connector brand plug and it has "N", "G", "H" molded into the plastic.]

    For Edison (PBU), L5-15, L5-20:
    Black to Brass
    White to Silver
    Green to Ground

    Not gonna mention L6-20, or my favorite L21-30, as that may confuse some people.;)

    And one more thing. Sloop, I've never heard a 100amp Stage Pin (2P&G-100a) called a mogul stage pin before--is this common in your teaching/area? It could cause confusion as there's also a 60amp Stage Pin (2P&G-60a), so what would that be called? Looking at the site, I see that 60-2H&GM1 and 100-2H&GM1 ARE 240V, "2 hots & ground," so maybe your electrician wasn't that far off. I've never used the 240V versions of these, has anyone? UC's site doesn't have pictures, so I can't see if it's a different pin configuration or just labeled differently. Now I'm curious...
     
  19. Van

    Van CBMod CB Mods Premium Member

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    I've seen and used Mogul stage pins before, they're much more common in film, as thats typically what you're plugging lunchboxes and spider boxes in with.
    < Wow run on sentence and ended it with a preposistion, wouldn't mom be proud.>
    But prior to my film work I had always heard the 100amp Bates referred to as a Mogul, so maybe it's a midwest thing?
    I always called 'em Moguls or Bates, 60's and 20's.
     
  20. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Charc, the color code was not directed at you, it just seemed a good place to re-state it for our less-experienced listeners.

    As for the above "not a problem": Electrically, the cable will function as intended, but if later someone other than you opens that connector (I think the clear covers are a great idea) they're gonna have to then open the other end, and then they'll question your parentage, probably not in a nice way.:)
     

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