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1 Wire vs 5 Wire

Discussion in 'Lighting and Electrics' started by Charc, Aug 12, 2008.

  1. Charc

    Charc Well-Known Member

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    I've been thinking about cable for use with threephase disconnects a fair amount lately. I've been wondering what exactly the advantage is to using camlock, and running five separate cables for a disconnect, versus using a 5 wire cable in the first place. I think the only advantage I could come up with was being able to use an amp clamp easily. However, aren't you just running all the cables to the same place in the end? Could you cut down on the amount of rubber, or what-not, used in jacketing if all the conductors were in one cable? Not to mention time in running the cable? Lastly, doesn't it look neater to run one cable, as opposed to five?

    Does anyone have an opinion on this matter?
     
  2. TimMiller

    TimMiller Well-Known Member

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    When you are playing with 4 awg having one big cable is fine. But imagine having a cable with 5 4/0 conductors, it just is not pratical. It is much easier once you get into the 2 awg range to have them all tied together in a big piece of rubber. It adds cost and extra weight. You also do not have the same cooling effect as you do with cables ran in "free air".
     
  3. Sean

    Sean Active Member

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    No, you'd have a similar amount of insulation....and probably more (filler material, etc to make the full cable assembly round). It may look neater, but the cable would be thicker (and hence, taller). There are often instances where that would be a problem--like arena floors, where forklifts drive over the cables (protected by cable ramps).

    Another thing to keep in mind: Sometimes you double the neutrals (for dimmers) and sometimes you don't use a neutral at all (some chain motors). In a tour environment, one would not want to run that cable every day needlessly.

    Have you run any 4/0 feeder? Say 100' or so? Just getting it out of the box will kill your back.

    --Sean
     
  4. soundlight

    soundlight Well-Known Member

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    As has been said, have you ever run four aught? Not a pleasant experience on any count. Also, if you're using 480V generators and using individual transformers at the dimmers, distros, etc, you only use 4 wires.

    I'll put it this way - the first time you're faced with lifting a 100' four-aught cable out of the bottom of a cable trunk, you'll know why they don't make five-wire four-aught.

    However, for lower power needs, 4/5 cable is great, and saves a lot of time.
     
  5. Charc

    Charc Well-Known Member

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    So 4/5 with cam breakouts would be cool, but otherwise, I totally see everyone's point. The most I've run was 250' runs of 4awg. The cable had some weight to it, but the amount of time I spent dealing with corners, doorways, and vertical sections bugged me. I totally see what you guys are saying about four aught. *Smacks head*
     
  6. malex

    malex Member

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    At a production company I worked for in Orlando, we had a multitude of options for our feeder. There were some 5 wire cables with cams for lower amperage uses that sat in a case that no one ever opened. Some of you may know his cable affectionately as horse c**k. We definitely would rather move 5 separate, flexible wires, regardless the gauge, that that heavy beast of a 5-wire.
    Also, there is a generator company in Miami that I have seen on numerous occasions that have the coolest shirts. They have their company name on the front and on the back it says " I ♥ 4/0" I've begged for one, to no avail.
     
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Showpower shirt: (paraphrasing) "Any day above ground is good!"
     
  8. JD

    JD Well-Known Member

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    All the disks in my spine screamed in terror when I read the first post! Yea, weight is a BIG factor. Also, I don't have a chart handy, but there is a de-rating that occurs in ampacity when all the conductors are in one sheath due to heat buildup.

    I am one who does not believe in putting cams on a piece of 6/5 either as it encourages such a cable to be plugged into a 200 or 400 amp disconnect. Even when the load is reduced, the cable itself is unprotected.

    I once did a gig for Blood Sweat & Tears where we were faced with a 1000 foot cable run. Part of the deal with the school was they would have their football team unload and lay out the cable for us. Now.. that's 5 pieces of 4/0 or almost a mile..... So, we have this 24 foot truck for the cable. The truck looked pretty empty as all the cable was on the floor. (Despite the springs being bottomed out!) They were joking and laughing about how stupid and simple it would be. No one was laughing by the end of the night.

    (My thanks to this day go to the late Aladdin Lighting and McMannus enterprises in Philly for supplying such an odd request)
     
    Last edited: Aug 12, 2008
  9. TimMiller

    TimMiller Well-Known Member

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    Reminds me of presidential stuff we were doing. It was either find a crystal sync generator or get the generator (though it was still very quiet) about 1000' away. But the other curve ball was that the cable had to be layed about 2' underground :D. The presidential people want all cables underground when they are outside, they do not want to see cable ramps everywhere. About 40 GI's had a trench dug in about 45 min, the cable laid in about another 20, so in about an hour they had a 1000' trench 2 feet deep, with 4/0 cable buried in it.
     
  10. zac850

    zac850 Well-Known Member

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    In addition to the weight thing, the electrical codes derate cables depending on how many current carrying connectors are in the cable. If you had a 5 wire cable for 3 phase, you've got 3 current carrying connectors and you'd have to derate the entire cable by (around) 80% (if memory serves, I'm not getting out my codebook unless someone really cares). To get the same rating you would then need to use thicker (heavier) cable.

    By code, we're not supposed to tape the cables together either, since binding them together technically turns it into one cable instead of 5 cables (though everyone ignores this).
     
  11. LightStud

    LightStud Active Member

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    Not everyone ignores this. 4/0 is very rarely banded, and then only for short rack jumpers. Hodding/looming wires every 3 - 5 feet does not turn it into cable. A wire is by definition a single conductor. A cable consists of two or more wires, plus filler fibers, contained in a continuous jacket.
     
  12. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Err Unless one has a fully balanced load with no harmonics or a delta connected load, do not you have 4 current carrying conductors?

    Also do you not have code related rules about rated cable based on what connector is on the other end and that determining length and conductor area? I'm reasonably certain we do...
     
  13. LightStud

    LightStud Active Member

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    COrrect.

    Provided the connector is properly sized for the OCD, the type of connector has nothing to do with de-rating conductor ampacity.

    E-1015s.
     
  14. JD

    JD Well-Known Member

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    Taping 4/0 together? Gee, the only thing worse than untangling a mess of wire is untangling a mess of really heavy wire! I always taught my crew to lay down one conductor at a time leaving room between each conductor. Not only did this provide air circulation and prevent the accidental building of real big electromagnets, it also made tear-down a lot easier as you would do the whole thing in reverse. These days, I see a lot of carnival companies that use a truck mounted wire wheel and just lay it out, but I've never seen anybody bundle them except for tail sets.

    As for neutrals, not sure if code has caught up, but yes, with phase chopped dimmers, you have to consider the neutral as a current carrying conductor. Maybe Steve would know. (In reference to thermal de-rating of wire by number of sheathed conductors)
     
    Last edited: Aug 13, 2008
    LightStud likes this.
  15. Chris15

    Chris15 CBMod CB Mods Premium Member

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    A] What is an E-1015? If it's something North American, a quick summary of what it is and does so I can work out what we call it would be good.

    B] What do you mean by OCD?

    C] Connector type won't affect derating agreed. But to be kosher down here, anything rated at 32 amps to meet standards must be at least 6mm2 conductor area per conductor, 63 amp is 10 mm2. So therefore if there is stuff like JD is talking about that has a 4 or 500 amp powerlock on it (newer ones are rated to 500 amp) and yet the cable is not rated to take 400A then something sounds fishy at least by Australian standards...
     
  16. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Err any unbalanced load with a neutral connected will have current down the neutral... You can star connect a load without connecting the neutral, but it would result in that point floating and that could end badly...
     
  17. JD

    JD Well-Known Member

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    My point exactly.

    E-1015 is a style of Cam that is rates for 150 amps as compared to the E-1016 which is rated for 400a. Unfortunately, the 16 is the one I often see on the 6/5. (Of course, 150a is a lot higher than 6/5 is rated.)

    As most locations provide a company switch with E-1016s on it, you should have a fused disconnect that has E-1016s on the input on 2/0 tails, and E-1015s on the output with fuses rated installed based on what type of output cable is on the 15s.

    "something sounds fishy at least by Australian standards..."
    The fish are the same up here. (They just swim half as fast but are twice as wide)
     
    Last edited: Aug 13, 2008

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