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  • Power distros for entertainment like bands & concerts or stage & theatre shows

    Hi all,
    First post.  I'll apologize in advance for my long posts or if you're members of some other forums that I have posted this in but would sincerely and genuinely appreciate your help.  I am not sure if I am on the right forum to ask the questions I am going to but would like you not to get too pissed at me if I am on the wrong one and kindly ask that you try to help me or point me to the right forums. 

    I have done a search here already for "power distros" and read many great posts regarding my questions and I think I have actually got most of them answered but just in case, I'll post my questions below.

    Long story short, I own a smaller lighting, video, sound, and event production company and have questions regarding electrical situations for it.  I have coordinated shows in the past where we needed to get power installed on the outside of buildings to do some outdoor events that required us to have more power than your typical 20 amp wall outlet provides but I'll admit, I was simply in charge of coordinating the electrician to come and install what was needed and simply was told by the sound guy to have a specific type of 50 amp connector (I think it was a 50 amp female receptacle) installed to have his power distro plugged into it to provide power for his equipment.  Well, now I have purchased more equipment and I am slowly doing larger and larger shows and a few 20 amp outlets is not going to take care of my needs for what I am looking to do in the future.  So.......   

    I believe my questions are basic because what I've seen in my head is common but maybe not.  Since I am now doing larger shows (but still "small" on many people's scale) on my own and want to be responsible for providing the sound and lighting equipment and running it and want to get into even larger events which will require more power, I am looking to have someone build a power distro for us OR.. purchase one to be used at various events when we do them in different locations.  We want to have a distro built that can be used as temporary power for us at the venues or places that just simply don't have enough power close enough to where we need to set up our amps, sound equipment, lighting and so on.

    I know that in order to know how much power we would require, we would need to know what type of event it is and how much equipment it will take to put out the kind of sound we want AND the amount of lighting or video we want to showcase the event as well.  But let's just "assume" that when we add up all the amps/watts we need, we'll need up to 6,000-8,000 watts for sound and around 30-35 amps for lighting.  Keep in mind, we use a lot of LED lights and our newer moving head lights are also LED so the power requirements for lighting has now changed dramatically.  Anyway, so either 50 or possibly up to 100 amps will be needed for different events.   

    What I would like to ask is what would "potentially" be needed for electrical needs in the way of power at "most" places?  I know this is a "loaded" question with all kinds of specifics needed (total calculations of equipment power needs based on total lights, amps, and other devices) but just to help you out, what I am pretty sure we need is a power distro that has an SOOW cable running from it to a 50 amp 14-50R style NEMA plug in receptacle.  I believe these provide either 50 amps on one 120 volt circuit or 2 separate 120 volt 50 amp circuits which would combine to provide 100 amps total.  That would be ideal for our power needs.

    To keep it as simple as I can, I believe I found what we will need in the form of a plug in which is common at a lot of venues such as a conference center, event hall, arena, school, a gym, a bar or restaurant, and many other places.  It is a NEMA 14-50R style plug.  Here is a link to what I'm referring to:
    http://www.myrv.us/electric/Pg/50amp_Service.htm

    Now, one question I have is regarding how much power is available at these plugs in "most" typical setups?  Is it 240 volts with 2 separate 50 amp 120 volt circuits or only one 50 amp circuit on a 120 volt leg? 

    In the link, it states that these plugs can provide either 120 or 240 volt service.  Since it has 2 hot leads available in this plug, from what I understand, you could have one 120 volt service on one side and another 120 volt service on another side which would total 240 volts to this plug.  If it is wired for 240 volt service, then we would need our male plug to be wired for 240 volt service and have a 4 conductor wire (with outside shielding of course) going from the male plug receptacle to our power distro box. 

    So one question I have is:  when we are trying to figure out how to design our distro, do we design it with the idea in mind that we need a 100 amp box that will allow 240 volts to come in and split off into 2 separate 120 volt "legs" (I believe that's the correct term to use...please don't hate me if it's not) that would be 50 amps each?  Or, is it something else?  Even though the 100 amp box is rated for 100 amps, from what I am told, it is "actually" rated for 2 separate 120 volt 100 amp circuits (runs/legs/whatever) so it would actually be capable of 200 amps total but is called a 100 amp junction center.  So, in the case of using a 50 amp NEMA connector and SOOW cable for the extension run to the power distro, having a 100 amp box at our distro center would be more than sufficient correct? 

    But here's the part where I'm confused.  If we have it wired up, would it make more sense to wire it for 240 volts and purchase 4/4 SOOW cable (our length of run might be 200 feet so I know that we would need 4/4 as a minimum but it might be 250 feet so I don't know if 4/4 is acceptable at 250 feet or if we have to jump to 2/4 SOOW cable) and have it wired for 240 service no matter what or only wire it for 120 volt service? 

    I ask because I am "assuming" that these outlet/receptacles "typically" are wired for 240 volt service with each hot wire supplying 50 amps of service.  Like in the link, it would send 2 separate 120 volt 50 amp services through the plug in, through the 4/4 SOOW cable and to the junction box.  Which would then be split into two separate 50 amp 120 volt services (legs) and to the breakers for the 20 amp outlets on our board. And with this, it would have a total available output for our 20 amp outlets of 100 amps. 

    If we have it wired to work for 240 volts, won't it still work in places that only have their 14-50R NEMA receptacles wired for 120 volts on one side as well?  In which case, even though it has the same receptacle, even though it's only wired for use of one 120 volt leg, we could still use that leg.  Or, do these plugs ALWAYS HAVE TO BE WIRED for 240 service? 

    If we only wired it for 120 volt service, wouldn't we be limiting ourselves to only having that single 50 amp service at our junction box (instead of a full 100 amps) or am I missing something here?

    As I stated earlier, "assuming" that we will AT LEAST have to have a 4/4 SOOW cable for a 250 foot run, I want to make sure that we aren't limiting ourselves if we're going to have this built with buying cable and so on.  And in that regard, I have also read that people have discussed the need to wire for 3-phase service which is typically 208 volts (if memory serves me correctly).  In which case, we would need to have a 5 conductor SOOW cable or something similar.  I know that this will add weight and cost to the cable but since the cable is already going to be damn expensive at 200 or 250 feet AND heavy anyway, even though it may add a few hundred dollars to the price, having the ability to also be able to tie into 3 phase service may be worth it right?

    Now, currently, the equipment we use is simply amplifiers and lights that are wired for 110/120 volt service and as such, I am probably going to at least "try" to keep it that way for simplicity sake.  So, we may not even need to worry about 3 phase stuff until we could get bigger.  But, I would like to hear the options if you wouldn't mind (and have read this far). 

    Also, I understand that the cost of a 200 amp box compared to a 100 amp box is virtually nothing so we will probably just put in a 200 amp box even though we will "probably" never need it.  I would just hate to run into the situation where we are doing a large enough event where we would have inflatables running (which takes a lot of power to run the fan motors and etc.) and maybe a larger show that needs more lighting and sound.  In which case, can we have two separate 50 amp SOOW cables going into this 200 amp junction box or is that something I'm way off on? 

    And now that I think of it, if we do have inflatables rented from a different company, will their fans and equipment "typically" be 110/120 volt or will it be 3 phase since they are using fans?  Or does it depend on which type of fan they use?  If so, then I need to consider this obviously.

    I have also heard of having an additional 14-50R plug or maybe only a 30 amp twist lock plug to allow you to run an additional power distro off of yours.  I suppose this could be done if we had another large amp rack that required a lot of power and we need to put them on the other side of the stage then this would be needed but for now, I think we'll try to keep them all close together.

    So, for a 250 foot run, will we be ok with 4/4 SOOW cable or will we have to jump to 2/4 SOOW cable to meet code? 

    And last, if we are running something that long, instead of purchasing the super expensive SOOW cable, why can't we simply use a 10-3 UF wire with ground cable (If we're only doing single phase)?  Like in these two links:

    http://www.menards.com/main/electrical/rough-electrical/wire-cable/10-3-250-uf-with-ground-wire/p-1469728.htm

    http://www.homedepot.com/Electrical-Wire/h_d1/N-5yc1vZbm7v/R-202316283/h_d2/ProductDisplay?catalogId=10053&langId=-1&storeId=10051#specifications

    Since they are both rated for outdoor use and we would be using some of our distros outdoors, why couldn't we use these cables instead of purchasing something that is 4 to 6 times the cost?  Regardless of whether we would use these or SOOW cable or not, I realize that we may have to cover them to protect them from peope walking on them or having a vehicle drive over them.  I have often wondered why carnavals don't have to have all of those SOOW cables covered so maybe it isn't a requirement.  I don't know and if anyone knows, please fill me in.  But if it is, I would think it would be for an SOOW cable as well.  If it is, then I seen no reason why we couldn't use the cable from the links I posted above and save some money.   

    I know these are questions about code and so forth but even though I haven't seen it done before, I am wondering why it wouldn't be acceptable since this cable is up to most codes or maybe even all of them. 

    Also, as far as the amount of power we would need for our runs, let's just say we would need at a minimum of 50 amps but the 100 amps would be more desirable.  In which case, is the 14-50R receptacle that is good for 50 amps for 240 volts also good to break it down to 2 separate 50 amp legs at the junction box like I am thinking?

    Any help would be much appreciated.

  • #2
    Welcome aboard.

    You have asked a bunch of questions, and you're in the right forum. Let me start by saying that a little knowledge of electricity is a dangerous (potentially fatal) thing. I'm not a licensed electrician, or an electrical engineer. There are several folks here who are, however. I'm going to assume that you are located in the USA; if not, then some of what is below may not be accurate.

    One of the questions you asked was about buying cable that is used for household wiring purposes, instead of SOOW cord. The first reason is that household cable uses solid conductors, not stranded. In order to be used as portable (temporary) cord, you must use stranded wire. Solid conductors don't coil very well, and will work-harden and break if you flex them a lot. The NEC (national electrical code) requires stranded cord in portable uses.

    I urge that you don't try to build your own distro box. Buy one from a company that sells them commercially. Buy one that is listed with an appropriate certification agency (such as UL). Your life and the lives of the musicians and patrons are worth it. In addition, you don't want an inspector to shut you down for a Code violation.

    The brief answer to your wiring question is that a NEMA 14-50R recepticle is a single phase, 3 pole, 4 wire device. The poles are one neutral leg and two "hot" legs, plus a ground wire. Each of the hot legs (often referred to as "X" and "Y") are 120 volts (nominal). Each leg is 50 amps at 120 volts. If a distro is wired correctly you have a maximum of 100 amps of 120 volt power available. Alternatively, you have a maximum of 50 amps of 240 volt power available. You can have a combination of 240 volt and 120 volt power available (depending on how the distro is wired), but you can't exceed the total current draw allowed by the main overload protection device.

    Peavey (and others) makes a nice rack-mount distro that uses a NEMA 14-50 plug. As a non-electrician, you can legally plug in to a 14-50 receptacle (it's what modern electric ranges use). You can't wire into a circuit breaker box on your own, however. Connections inside a breaker box are required to be performed by a qualified electrician.

    I'll ask more knowledgeble folks chime in as appropriate. Mark C.
    "Good tools are expensive. Cheap tools are damned expensive."

    Comment


  • #3

    100 amps is a lot of power for sound and light.

     

    I have a couple 50A distros that power with a L14-50 range plug, and a couple 30A distros that power from either 2x 15A edison or L14-30 twist.

    Comment


    • lonotes
      lonotes commented
      Editing a comment

      Mogwix wrote:...and a couple 30A distros that power from either 2x 15A edison or L14-30 twist.

       

      What's the benefit here? Reduced noise due to common ground?


  • #4
    You are exactly the kind of customer the cheat sellers are looking for. In order for a con to work, the buyer must think they are smarter than they are, they must be greedy and think they can get something for nothing. You have a long way to go before you understand the commodity supply and material business. Companies selling materials based on traded commodities have very similar costs, so when a product is offered at below the cost of manufacture, it's almost always a scam, a cheat, etc. Companies can't sell commodity products at a loss and remain in business.

    As far as you not liking my comments, calling me petty... too f'ing bad. There are other folks who read these threads to learn even if you choose not to. I stand by every one of my comments as accurate, just because you do not understand the answers doesn't make them wrong buddy.
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie

    Comment


    • theshow
      theshow commented
      Editing a comment

      Aged,

      Where did I say you were wrong?  I'll ask you to point that out.

      And I'll ask you to point out where I haven't learned something as well.

       


  • #5
    Going to 2/4 cable will require the use of pin and sleeve or specialty multiple (ie. mining, foundery or industrial) type connector.

    Single pole connectors are not legal with multi- conductor "so" cable, and Tweco connectors are no.longer legal or acceptable for line voltages (class 1).
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie

    Comment


    • Craig Vecchione
      Craig Vecchione commented
      Editing a comment

      I think the need for a 120/240v *100 amp* distro needs to be verified. Based on the OP's first post and description, I can't imagine his needing more than the typical 50a distro.


      And as Andy has already suggested, renting anything larger or longer is definitely the way to go. I'd have to ask the OP how many times he's worked a big venue that provided pin and sleeve power. It makes little economic sense to carry all that copper inventory for only a few shows per year.


  • #6
    Yeah, right....
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie

    Comment


    • #7
      Those that do not really grasp the situation perpetuate mistakes solved many times before them out or either stubbornness, stupidity, or a combination of the two. Have fun and so long
      -------------------------------------------------------------------------------------------------------------------------------------------------------------------
      Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

      Currently product development engineer: Mesa Boogie

      Comment


      • Keyrick
        Keyrick commented
        Editing a comment

        Actually, you may see some savings if you look at the voltage drop of your different gauges.  For instance, you could run a 100 foot extension cable from the power source utilizing # 4, and the remaining 150 feet with #6 to your distro and still be ok with the amount of voltage drop that you encounter with your load.    That would provide you with some savings in your cable purchase.  And when you don't need it, you don't use it.  I haven't done the calcs because I don't know what your loads would be, but the above is an example of where you may be better served breaking up your extension cable requirements. 



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