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Is It Safe? Making Cables

Discussion in 'Lighting and Electrics' started by Cue3, Mar 13, 2003.

  1. Cue3

    Cue3 CB Data Analyst Premium Member

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    Here's the deal...after a short lesson on making cables from dvsDave, i decided to start making my own stage pin to edison converters. I was very careful but unsure when i found out that fresnels uses three differnt wires (black, white, green), and our S4's only had two different wires (two white, one green). I figured that it must not matter which one recives the hot and which side gets the cold. But is the same true for fresnels? I also recall that you can put a S4 bulb in either way, but fresnel bulbs only go in one way. So is it safe to use my cable on both a fresnel and a S4? Also, after seeing my cable, my theater director wanted to make them in bulk, so he asked if i could teach a small group of students to make them...i just dont want to teach them the wrong way....thanks to anyone who can help.

    Matt
    Lighting Designer,
    Stone Bridge High School
     
  2. delnor

    delnor Active Member

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    Make sure that they match up correctly. If you are doing stage to edison converters... On the stage plug side you should have the hot wire going to the pin that is by itself, and match that up on the edison side, which I believe is the smallest prong if I remember correctly. Then just match up negitive and ground. Even if a pirticular fixture does not require proper polarity to opperate you should always make your cables with the proper polarity. That way if they get mixed up you wont damage a fixture or lamp.
     
  3. ship

    ship Senior Team Emeritus Premium Member

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    The reason that Fresnel - Medium Pre-Focus P-28s lamp bases are what’s called polarized is for the same reason your living room table lamp is probably using a polarized plug. The neutral wire goes to the outer shell and the hot goes to the center contact. This way if you are putting in a lamp while the fixture is “hot” or plugged in, should you touch that outer shell or screw base of the lamp, it does not in touching the lamp base give you a shock. If wired properly, the lamp shouldn’t contact the hot wire until the base of the lamp is well within it’s lamp base and away from your fingers. Thus it won’t shock you as long as there is no current passing thru the neutral wire as in most instances there should not be.
    Read the instructions provided your plugs especially where they reference strain reliefs and how much wire to strip back. Don’t forget to mark any cable you make in some way as it being your theater’s including with a phone number or should someone visit, your good work might just grow wings by accident.

    As for making cables in bulk:
    Start an assembly line. Don’t have one person at a time assembling one entire plug at a time. It’s too hard to ensure quality control over the entire project if there are a lot of cooks baking with their own skill level of cooking. Have one person strip the wire, another wire the plugs, another ensure that the plug was wired properly and close it up. When you do this, you can also employ any skill level of person in getting the job done. Switch positions occasionally, say have one person do the stripping of the wire for 5 adaptors, than switch to someone else. That way with repetition, you can perfect one part of the skill at a time. If you try to master too many skills at one time you will fail or forget something if not at least do none of them as well as you could.

    PS. I make cables for a living. When I need to and with an assistant, I can make 80 a day with logos and other markings on them, and each of us getting phone calls to answer or interrupted about every 15 minutes. Reason we can do this is because we do what’s called “dancing with each other.” This means you work as a team each doing moves and complimentary moves in support of one effort. We also have power screwdrivers - but our fingers are getting a bit old to be doing such things manually. For insance, when one person pulls the wire off the spool and walks it off, the next person cuts it when it gets to the proper length. Than he or she walks the cable out to it's length wile the original person walks back to the spool to cut the second person's length.

    I forwarded a long article to the webmaster of this website I had written for another website on making and repairing cable. You might at some point see it. Had a few more details on the subject.
     
  4. dvsDave

    dvsDave Benevolent Dictator Administrator Senior Team CB Mods Fight Leukemia

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    Editing for content

    And it's a LONG article... it is 10 pages printed.... I am hesitent as to whether I should integrate it into the existing guide or make it a seperate guide. Well, either way, at least some of the corrections, techniques, methods, and safety guidelines will be on the site shortly.
     
  5. ship

    ship Senior Team Emeritus Premium Member

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    I would divide it up into the two part it should be - cable repair and putting plugs on. Have fun if I touch it any more, it would get longer. You might also want to if editing it want to try the technique yourself first so as to understand it fully. Or send them off to a third party to study and try out. What works for me and where I work might be a bit complex for others in presenting without study. I do highly sugguest throwing out the utility knives however. I don't let anyone use them where I work.
     
  6. Jo-JotheSoundDog

    Jo-JotheSoundDog Active Member

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    making cable

    I would like to throw out the suggestion of giving a local professional theatre and speaking with their master electrician. Most of the guys I've known would be more than happy to teach younger technicians a thing or two. And as far as utility knives go, I wouldn't be so fast on throwing them out, I still know a lot of people that teach that style of cable making. But you do have to be very careful with them! I can still cut and strip down all three leads of an XLR faster with a utility knife than most people can do with a proper wire stripper.
     
  7. Reggie

    Reggie Member

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    Re: Making Cables

    Ship, I'll address to you since you made the comment, "Throw out the utility knives". I have been working in electrical for some time and while there are quite a few patened devices for stripping cables like Romex and rubber cord, a lot of us will turn to out electricians knife or to a "utility knife" to remove the outer jacket. What do you use and reccommend to remove the outer jacket on rubber cords such as type SJ, SO, SOOW?
     
  8. ship

    ship Senior Team Emeritus Premium Member

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    I use a Specilized Products #NT2267 cable slitter http://www.specialized.net/ecommerce/shop/layout.asp?product_id=210X800 to slit cable jackets. Used one even today on some 8/5 SO wire. Once you get used to the technique of hooking the jacket than rocking the blade back to ride the cut on the jacket while not cutting into the insulation below, it works well - to the point that you can remove a layer of insulation or heat shrink at a time without slitting the cable below. Only costs about $21.00 each and it looks kind of like a juice harp.

    Otherwise, if not slitting the jacket, to make a cut into it so I can remove the jacket as a whole and not slitted such as for a plug on a cable, I use professional Klien Journeymen 2000 series Dikes #J248-8 with the beveled head and case hardened tips that sell for about $25.00 each. When and if they get dull, it's full warranty. http://www.kleintools.com/index.html With such a tool I grab the wire, Pull and rock it off to the side than cut down on it to ensure that the wire I cut within that pinch is nowhere near the insultaion of the conductors below. Five such pinch, pull, cuts, and most jackets on a wire will pull right off. Otherwise, where needed, just the carefully placed pressure of the always sharp blade is sufficient to cut the remaining jacket when the wire is flexed to expose it.

    It's a practice thing but one that ensures that no matter how great you are with the knife, you don't apply just a wee touch too much pressure with a knife blade directly onto the cable jacket and insulation of the conductors beneath. "I never cut too deep and by far am too much of an expert to fold my wire at the cut to ensure I did not cut into the insulation." Let's face it we all once in a while make a mistake, using the dike method for cutting a cable jacket is just much easier to do without thinking about it, and much less likely to cut into the insulation.

    Once that cable is stretched with use, all it takes is the slight cutting into the jacket and you have conductors exposed - and that's why I am adimate about not using knives. Get a good pair of dikes, try the technique and see if amazingly enough it does not seem the most safe method not only for students but for all to use. No on type SC cable, I'm using medium cable cutters and slitting the jacket down to the wire, but on multi-conductor cable it works uniformly and safely.

    Should I have to cut and slit some #6 THHN building wire, than sure, it's that utility knife, I'm not about to waste the blade on my medium cable cutter on such wire, much less I'll probably have to slit the jacket anyway to get it off and with that type of insulation, the utility knife blade works best. If I need to make some more solid 14GA wires for CamLoc connector strain reliefs, and it is not just pulling off, I'll even consider using the utility knife to remove the jacket. These execeptions are that with building wire, the conductors are much larger and have less strands to them than a cord's wires that are easily cut.

    As for utility knives, I use them and specify them to be used for cable looms. But only with one specific blade that mimics the above one. This is a topical debate that I was just discussing today in the idea that perhaps I would supply crew chiefs with shows blades of the type so they could thus supply the union toadies and everyone else damaging my cable, with a good knife blade. Just takes one misplaced cut on the jacket of a cable with a normal utility knife blade and that cable is damaged. We have hundreds of thousands of dollars in cable with cuts in it that is not coming from the shop, it's coming form the road. All because it was too close to lunch or some stage hand was distracted while cutting apart cable looms. My starting such a trend could change the industry considering the level of tech I am working at. Give it a few years should such a option be adapted by us.

    A hook blade is the solution. (And everyone wonders why I would want a copy of McMaster Carr at home. Part number 4927a18) Stanley part number 11-961 is a normal sized utility knife blade that will fit into all utility knives, but as opposed to slitting with the downward pressure, slits with the upward pressure. Now consider this idea, you hook the tape from underneath and cut by sliding the blade along the tape with a slight downward if not upward pulling pressure. That as opposed to a downward pulling pressure that if even slightly too deep will cut into a cable jacket if not inner conductors.

    In the shop, I mandated the use of such blades and repairs on cable has gone way down. The only problems now are in old repairs before the current method, or in field repaired cable that's usually electrical tape forming a temporary fix that will peel off, or better yet, marked in yellow so such a cut can be properly repaired. It is extremely rare that a tech person in the shop while using the proper cable slitting much less tape cutting blade will slit the cable. There is no cutting edge along the surface exposed to the cable jacket so there is nothing to be damaging the jacket. Such blades also work faster and easier.

    Again, try these new tools before you form your ending opinion on skill being all that's needed to use a utility knife. In addition to that cable slitter, today I used a actual electrician's knife today. I was slitting the cable on some 8/4 flat cable and needed to penetrate the outer jacket in getting at the inner conductors. I only pull out the real knife when it's necessary to do such things. I even have a NMN cable stripper that's only used for that purpose. Takes longer with any such tool as it does with a basterdized but everyone uses knife to be as careful as necessary to slit cable jackets. Five grab/pull/cut's and it's done. Under 6 seconds and the cable is stripped. I don't have to worry about some complex cable jacket slitter doing a proper job, it's just done. If using cable that does not pull, the dikes are much easier to control the depth of cut which varies with a knife due to it's sharpness. Indent a slit into the jacket and fold the cable, you now have a cut that is vary rare to be too deep. Simple as that.
     
  9. Starlitr

    Starlitr Member

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    I've been making cables for 40 years and just learned something new.

    Thanks guys!

    (I had developed some similar skills and techniques, but a few adjustments/tools that were mentioned have me singing a happy tune today--you see I have 300 cable connections to re-do because I am installing new lighting system in the next two weeks. I bought a few new tools and have already done 20 connections in the time I used to do 15. And the best part is that I am confident that they are "right" and will last. That hook blade is GREAT! Now why didn't I think of that?)

    Steve
     

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