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Silly Power Question

Discussion in 'Lighting and Electrics' started by liteman, Dec 27, 2007.

  1. liteman

    liteman Member

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    Hi all,

    I'm working on a show in an old venue. I have access to a 60A 240VAC event power plug (NEMA 18-60 Plug).

    My desire is to bring in a few moving lights and wash units and supplement it with a small conventional package.

    I was thinking I would build a custom distro for this. I was going to basically wire the first hot leg to Phase A on my dimmer pack and throw a 20A breaker on the end for half of my intelligents, and do the same with the second hot leg, for Phase C and the other half of my intelligents.

    Right now, my current plot requires that my total intelligent light load is about 10A/120V on each breaker.
    My total conventional light load is about 40A/120V on each phase.

    My question is:

    If I rent an ETC 12 x 2.4kw Sensor dimmer pack, which should really use 120A, will it still work given that my available power is less than that? Does it matter since I'm only loading each phase to 40A/120V, which is available, or will the pack not work at all without 120A?

    Any responses, ideas, alternatives, or suggestions will be greatly appreciated.

    Happy Holidays!

    --liteman
     
  2. David Ashton

    David Ashton Active Member

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    The dimmer pack will only draw less than 100 watts, it is the load that you plug in and bring up that is the crucial factor.You can load up the dimmer but as long as you only bring up a balance of power at any time you can get away with it.The pack will work perfectly well.
     
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  3. liteman

    liteman Member

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    Excellent. That's just what I wanted to hear.
    Thanks!

    One more silly power question:
    I know that most moving lights these days can run at 120V or 220V. When they run at 220V, are they running off of a single leg at 220V, or two legs of 110V?

    My real question is, using the above event power, can I hookup my moving lights directly to the 240V interface? If so, how do both legs of power get into the moving light? Do I need special power cables?

    Also, what's the safest way for me to get the cam cables for the Sensor Pack hooked up into my custom distro without me having to wire cams out of my distro?

    Thanks again for all of your help and your (incredibly speedy!) responses.

    --liteman
     
  4. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    liteman: STOP! If this is indeed the plug to which you are referring, it cannot safely be used for stage lighting, or anything else for that matter, as there's no electrical ground.

    Secondly, you haven't told us what size the circuit breaker or fuses are supplying that receptacle, which is more important that the plug specifications.

    Thirdly, your questions indicate that you don't have enough knowledge or experience to do what you're attempting without a Licensed Electrician.

    Sorry to be blunt, but I don't want you or anyone else to be harmed.
    allthingstheatre is only partially correct regarding underrating dimmer loading, and didn't pick up on the fact that you refer to a NEMA 18-60 as a 60A 240VAC device, when it is actually a 4wire, 3ø, 120/208VAC connector, with no ground.

    Welcome to the Control Booth! We'll do our best to help you with any question, but we'll also tell you when we can't, for safety reasons.
     
    liteman likes this.
  5. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    Howdy liteman,
    When it comes to electricity--the rule of "if you have to ask, you should not be doing it" applies.

    Aside from not knowing how or what that 60a 'event plug' is wired (is it WYE power, is it delta power, what guage wire, how is the ground or neutral run, is it 'really' 60 amps or is that just cause the plug is rated for 60--it could be 100 or it could be 30--is it breakered or direct tie to a panel and what is THAT say, and is it single or 3 phase etc etc etc)--cause in electricity it is risky and dangerous to assume anything and there are many factors to consider for safety and proper use.


    There is a liability restriction to questions that can be answered here on CB (most being for rigging and high voltage electrical wiring) for reasons of safety and liability because many of the participants on CB are learning students in HS and college. The Senior-Team Moderators & Controlbooth Owners, who are all experienced professionals, have drawn this line for its CB members so as not to permit posting of potentially dangerous or unsupervised 'DIY instructions' which may cause injury or harm to someone less experienced or just learning.... We do not wish to seem to play down the dangers and risks of doing certain rigging or electrical work. Reading a post on a web forum is not "formal training" or can cover completely all the safety aspects of any project... Supervision and proper training in certain aspects of live entertainment is required and a must before anyone should take on such a project. I am not saying you may not have some experience in electricity--I am simply saying that when in doubt always yeild to a professional electrician or rigger and consult them first.

    Please consult a licensed electrician for your project and please be safe--we want our members to stay around. At the least, you could damage or destroy your equipment with improper wiring, and at the worse you could cause injury, death, electrocution and fire from mis-wiring or overloading...

    -w
     
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  6. liteman

    liteman Member

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    Thanks for your replies,

    I apologize, I should have been more specific. I didn't assume that it was wired at 240V/60A because of the plug rating, it is clearly labeled on the disconnect that the plug is wired to.

    In addition, each of the poles on the plug itself is labeled, as well. I've attached a picture of the plug that I took on the first site survey.

    You're correct in picking up in my lack of knowledge about some of these things. I am really more of lighting designer, and usually let the production companies handle the setup, but this is for a small, non-profit organization, and I'm friends with the director, so it's a special circumstance. But I do have a fairly strong understanding of electricity and what is safe and what is not.

    I would have never known that the Nema 18-60 is normally used as a 3-phase with no ground. i just assumed that it is normally used as it was wired in this situation, but clearly, the original electricians retrofitted it, into what seems like event power.

    The top pole is labeled as neutral, left and right as the hot legs, and the bottom as ground.

    Based on these labels, and the labels on the disconnect, I came to the conclusion that it was a single phase 240V/60A with two hot legs, a neutral, and a ground.

    I certainly appreciate all of your concerns. I would never want anyone, including myself, to be harmed or put in danger by anything that had my hand in it, and I assure you that I will be the first person to step back if I even have an ounce a doubt in what I am doing.

    I was a little weary about a few things that I had never had to deal with before, as I've always worked with an abundance of power and normally let others worry about power issues, which is why I came with my original question.

    Again, thank you all for your responses, and your concerns - I appreciate them all.

    -liteman
     

    Attached Files:

  7. jonhirsh

    jonhirsh Active Member

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    In that photo it looks like top, left, and right are labeled H for hot and the bottom G for ground. That is a type of three phase power. Are you positive that the top said neutral?
     
  8. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Glad we didn't scare you away. I'll now address some of your questions, but I'd feel better if you had a more experienced electrician helping you.

    The Sensor Pack, SP6, is normally set up for 3ø operation. It needs to be modified by its owner for single phase, GNHH, operation. I'm not positive, but I think dimmers 1-6 are on one leg and 7-12 are on the other, when used in single phase mode.

    All of your intelligent lights are set to operate on 120V, correct?

    You never told us the size of the fuses or breakers, or wire feeding the 60A receptacle. Measure the voltage on the receptacle to verify that the pencil labels are correct. Are you dealing with a venue maintenance person or some other building representative?

    Another issue. If it is in fact a 60amp breaker protecting that outlet, you'll need to wire your plug with #6 or better #4 wire. Then find a set of E1016series-compatible Camlok-type connectors to mate with the Sensor pack. Those connectors wired with #4 or #6 wire are not a common item, in any company's rental stock. Plus the neutral MUST be oversized.

    That's as much as I feel I can give you. Start a new thread in the New Member Board introducing yourself. We're lovable, but nosy. Tell us where you are and what you've done, and where you'd like to be and do. We like other's websites, and definitely post pictures of your benefit when it's done. We love pictures, there's a lengthy thread here.
     
    Last edited: Dec 27, 2007
    liteman likes this.
  9. icewolf08

    icewolf08 CBMod CB Mods

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    If your Intellignet lights really only have a total load of 10A it would be a lot safter to just put them on a dimmer. I know that most intelligent gear doesn't like being on an SCR, so if you can spare two slots in your 12-pack you could put a CC-20 or R20 module in to feed the MLs constant power. In a pinch if you set the dimmer to switched mode you could probably get a way with running the MLs on a dimmer. This would be by far safer and easier than building a custom adapter.
     
  10. JD

    JD Well-Known Member

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    A plug like that would give me pause for thought. Three phase components cost a heck of a lot more that single phase parts. So, beyond the question of why a contractor would put the wrong receptacle in, is why would they pay so much extra money to put the wrong one in? (!)
    The two answers that come to mind are:
    1) It really is that type of power.
    2) It wasn't a licensed contractor that installed it.
    In any case, "Danger Danger Will Robinson!" Someone indicated to you that it is HHNG, but it needs to be checked out or better yet avoided!
     
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  11. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Hey Liteman, From the sounds of it I think I know about as much about electricity as you do. My vote is don't try it. I wouldn't. There is a lot of guess work here. If you make a mistake you could kill yourself or destroy the rental dimmer. Neither of which is an acceptable risk in my opinion. I would go back to the venue and pursue the what have others done route. Somebody KNOWS how it works. If they don't hire an electrician to figure it out. Even then I wouldn't try any of this without a heart to heart chat with the good folks at ETC and your rental company.
     
  12. avkid

    avkid Not a New User Fight Leukemia

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    Here is a rather simple answer-
    No Ground=No Go
     
  13. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Not to you specifically JD, but why does the NEMA 18-xx still even exist? Where could you use, per NEC, a connector without a ground?
     
  14. JD

    JD Well-Known Member

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    At this point, you are probably asking yourself, "Why did I ask? I didn't expect to get jumped on!"

    I apologies for all of us who may have come off sounding harsh. The truth is, after enough years in the biz, we all know someone who has either gotten killed or seriously wounded when it comes to the areas of electricity and rigging. For each one of those incidents, we can usually recall ten more where a lot of equipment got damaged. It is from this perspective that we may go over-the-top when safety issues come up. But, is it really over the top if in the end you save a life?

    I'll also be the first to admit, most of us here have at one time or another violated our own guidelines and dogged a bullet. Most of us look back and shake our heads at our less experienced selves. The bottom line is that this is a job, and should not involve Russian Roulette and the possibility of not coming home at the end of the day. Most of us love what we do, but I have one more saying for the rule book-

    "When in doubt, sub it out!" Let the promoter pick up the bill of course ;)
     
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  15. JD

    JD Well-Known Member

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    277 x 3, without a ground? The only thing I could think of would be some form of heating unit. But then again, why would such a thing be portable and have a plug on it! I guess my answer would be- "I have no stinking idea!"

    EDIT:
    Ha! Check this out, if you go to the same site that specs it as a 277x3, and click on the matching receptacle, it lists that as 120/208 !
     
    Last edited: Dec 27, 2007
  16. liteman

    liteman Member

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    Thank you all for your replies. They have been very insightful.

    Again, I certainly don't want to harm anyone or put anyone or anything in any danger.

    After reading all of your thoughts and responses, I decided to contact the maintenance fellows and see if they know more about the power in the building. I'm awaiting a response from them. Unfortunately, I'm about 3,000 miles away from the venue, working on another show, and won't return until the day before we load this show in, but I will have a friend confirm the amperage, voltage, and polarity of each of the poles of the plug.

    After I'm able to confirm my initial thoughts on the wiring of the plug and speak with the maintenance guys at the building, I feel like I will be able to make a more informed, confident, and safer decision about how to approach the situation, and if bringing in an electrician becomes necessary, I assure you all that I will take that step.

    I'll be sure to let you know what the result ends up being, and how everything works.

    Thank you all for your time, patience, and insight. I appreciate all of your comments very much.

    Happy Holidays!

    --liteman
     
  17. BillESC

    BillESC Well-Known Member Premium Member

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    Good answer.

    Rule of thumb... Ring it before you bring it.
     
  18. avkid

    avkid Not a New User Fight Leukemia

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    That's rather hard to do with a PA.
    :twisted:
     
  19. David Ashton

    David Ashton Active Member

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    Sorry but I can't understand the problem here,
    It has got an earth
    It has got a neutral
    It has got 2 phases
    It is NOT a 3 phase supply
    It is a perfectly safe and normal 2 phase supply
    It is a common practice in some parts of the world to use 2 phase for lighting and one for sound in the mistaken belief that this will reduce interference levels, now if the advice I gave last night is wrong I would like to know precisely why, thanks.
     
  20. icewolf08

    icewolf08 CBMod CB Mods

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    The problem is that the connector type is specified for a different kind of power than what the OP is saying it is connected to. I would assume that you have similar rules in Australia governing what connectors are designed for what. This is the reason that in the US, the "Old Style" key out twist lock connectors are no longer approved connectors. They were rated for two different electrical loads and there was no what to tell what was wired to them by looking.

    It is quite possible that this is not a safe 2 phase source as it really shouldn't have been wired as a 2 phase source. The connector (as derek pointed out) is designed to be a three phase connector with no ground (HHHN). If a licensed electrician did the wiring, one might not want to trust them as if the connector is wired the way the OP says, then it is wrong. This is why it should be metered to find out what is going on. If you had a device with the male of that connector properly wired and plugged it into the outlet wired the way the OP describes, it would not work correctly and could be dangerous.

    Also, the other thing I wanted to point out is that it is important to meter the system anyway. The OP never mentioned what kind of 3 phases service is in the building. If they have a ∆ (delta) tap transformer they could run into issues making the adapters they want if one of the hot legs in the connector is the wild leg. In a Y tap situation they would be OK (in theory) but then it isn't a 240v system, and I think that is important to point out. Hot to neutral in 3-phase Y is 110v, phase to phase would be 208v.

    Here are diagrams: [​IMG]
    [​IMG]

    Many newer MLs have ballasts that are capable of working with 110v to 240v AC input. This is true. In the US that usually means that you are either connecting to a standard PBG (edison) or 2P&G (stage pin) connector for 120v operation. You would then have a different connector for split phase operation at 208v where you would have HHG (possibly an L6-20). For true 240v operation I am not sure what connector you would have, or if many people even run their lights at 240v in the US, but you would have a connector with hot, neutral and ground.
     

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