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Cable Repair

Discussion in 'Lighting and Electrics' started by ship, Feb 19, 2004.

  1. ship

    ship Senior Team Emeritus Premium Member

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    “Hi Ship, I have a quick question for you regarding repairing cables....
    I was always taught that if you damage or if it gets cut in half, that you basically stick a new plug on each end and give yourself 2 cables. In some instances this is quite acceptable but not always.

    My problem is that repairing even a simple 3 core power cable causes the repaired area to be rigid and thus susceptible to breaks on either side of the join.

    I was taught to stagger the joins on a multi core cable (where the individual cores are insulated) to ensure that you don’t end up with a bulge, and to limit shorts.

    Eg:

    Core 1 --------xxxxx-----------------------------
    Core 2 -------------------xxxxx------------------
    Core 3 ------------------------------xxxxx-------

    Where xxxxx indicates a join.

    Each join is soldered (keeping the join to about 6mm), covered with heat shrink and the exposed cores are then wrapped with electrical tape to make up the missing outer insulating cover. The whole area is then covered with a length of heat shrink.

    This works perfectly for installations but I am not all that happy with the results for most other applications as the cable is continuously rolled and unrolled etc. “


    This is my method:
    What you describe is a rolling or offset line splice. This is a NEC approved method for line splicing but only when done properly and you are not. First heat shrink is not a approved method of replacing the insulation over the conductors for four reasons. First it in it’s normal type, it is not water proof, second with age and flexing it can tear, re-expand and move, third unless your solder joint is completely smooth, it can develop tears or punctures in it, and forth the largest reason is any protections you do to the wire must provide at least an equivalent if not 1.½ times the amount of insulation around the conductor per what was there before the splice. In addition to that, should there be a heating of the wire by way of too much amperage or voltage drop or the solder is a cold solder joint, the heat induced at the splice can be enough it will either melt the solder and allow the wires to become separated, or burn thru/cut or what ever the heat shrink. That’s just the heat shrink, electrical tape is not recognized as a permanent insulation replacement, nor will most of it hold up to your purpose without creeping, peeling etc. than it also will not be water tight. Electrical tape, especially typical store bought electrical tape has problems with heat, humidity and cold, and even if it were wrapped around the repair in sufficient thickness to reproduce the insulation covering the conductors, it still most likely will not be permanent, flexible, water resistant or adhere to the cable jacket strongly enough.


    The method of splicing cable including rolling splices is primarily used for power supplies to outhouse, sheds and barns when buried or supported, otherwise not an approved or normal way to join cables for power. Such cables would not be subject to flexing, coiling and other abuses that your power cords would be. When such permanent install splices are done also they follow a specific set or rules for how to do so and how to replace the insulation between conductors. Soldering the joint while still acceptable has for the most part also been replaced by other splicing methods which are easier and stronger.

    Your method would be fine for splicing multi-channel/pair data cable or sound snakes if expensive enough to try and save at the length, but for live power I would avoid this method and remove any such repairs from the inventory. On the whole, the rule of thumb for my application is there is no splices in live power cords without UL listed connectors and plugs between two sections of it. Simple rule which prevents guess work or possibly unsafe conditions.

    Cable is cheap enough that if becomes damaged or broken, just replace it. If you cannot afford to replace what is not safe to be repairing, you should not be using it. Even on multi-circuit Socopex cable, if there is a cut in a conductor’s insulation, cut the cable there it’s part of the price of being in the business. You do not compromise safety. Ever. We all know this but have our own ideas of what is safe often based upon a lock of knowledge about it. By my standards, even if there is only a cut in the jacket and the insulation on a conductor exposes bare wire, cut it. Broken/cut strands even if for the most part the conductor is in tact means resistance at that point thus heat. This is what causes airplane crashes as I watched last night 12/17/04 on NOVA - a PBS show. Basically with heat the insulation in some planes develops cracks. With water, they arc together and cause a fire that brings down planes. Same concept with our cable, unless absolutely water tight but still flexible enough, even repaired cable can arc from just a little crack. Data cable does not have enough voltage to arc between conductors for all intensive purposes, the worst that will happen is you loose a control cable. With that repairs can be done but frequently are smarter to just cut also because they have the nasty habit of re-breaking or shorting later. Basically, if there is conductors/bare copper exposed on power cord, cut it.

    CABLE JACKET REPAIR:
    If you are repairing a cut in the cord and after inspection of the conductors, there is no exposed wire, it is safe to repair the outer jacket as long as no more than 50% of the circumference of the cable has been compromised. The reason for this is as the cable is stretched, unless at least 50% of the neoprene or thermoplastic is still linking the two sections together, it very likely will tear free of any repair re-exposing the inner conductors and adding stress to them. Also if the cut runs the length of the cable by more than 12"(300mm) as an absolute maximum, it is not worth repairing.

    In addition to these dimensions, cable showing signs of age such as dry rot or other age, temperature, chemical or other abuse related damage such as crushing or extreme bending as a whole to the cable should not be repaired.
    First if the writing either imprinted into it or written on it’s side is no longer observable along the majority of it’s length it no longer is Code Compliant for use, you need to be able to read what the cable is gauge/conductor/voltage wise plus the manufacturer. Second if you flex it and it shows little cracks all over the jacket which are more than just minor and surface level, the cable’s jacket has been compromised and should not be used. It is no longer water tight, dielectrically safe, or offering physical protection sufficient to protect the conductors - it’s gonna break again. Remember, this is power cord, it has a service life, don’t push it past that because if the outer jacket shows especially rot, the inner conductors will very likely have just as much damage and often be oxidized - air and moisture making it higher resistance. If the writing has warn off, especially if the neoprene becomes about slick and shiny in appearance instead of matt finish, it’s often about on it’s last legs for age and use and most of the time it’s inner conductors will be oxidized also.



    I use three main methods for cable repair that are based off the line splicing techniques in Division 2 of American Electrician’s Handbook 13th Edition by Croft/Summers.

    XLR/DMX Cable Repair: Not worth much, repairs to it’s jacket will be less electrically permanent repair and more or a permanent nuisance repair to it. First if the cable has any glue remaining from tape once covering it, the remaining adhesive needs to be completely removed by Goof Off or Goo Gone. Avoid abrasives on the cable jacket such as censers, steel wool or sand paper, it will not do a proper job of removing the adhesive and might damage the cable’s ability to accept glue. If the adhesive, paint or what ever is on well enough Goof Off will not take it off, leave it in place. Next the cable will be cleaned to remove the Goof Off and any dirt with Naphtha. Adhesive does not stick to dirt, oil, much less Goof Off a adhesive remover, your cable must be clean. Next apply a light layer of rubber adhesive to the surface extending beyond the cut by at least an inch.

    There are three types of adhesive that are acceptable. First is rubber cement such as bicycle tire repair cement. This will work on neoprene/rubber insulated jackets but not thermoset or thermoplastic jackets as well. You must let the cement dry before you apply anything to it or it very likely will melt thru what you apply to the adhesive. Rubber/butyl/neoprene adhesive as opposed to rubber cement otherwise works well depending upon brand and type as long as it is allowed to set up. It will also work slightly better on the plastic types of wire. Some trial and error is necessary, as with a method of application of thin even coatings. The best adhesive for general purpose cable work on all types is 3M #2141 Rubber/Neoprene Adheasive. The smallest quantities available for it is in 1 Quart cans, and because it is fast drying, use of a glue pot or other specially designed applicator is necessary for more than one time use from the remaining quart. In other words, put it in a glue bottle, open the can than re-seal it, or any other method normal to glue application will expose the adhesive to the air and it will set up. Once the adhesive thickens, it is not possible to thin it and often will not be as strong in adhesion.

    Glue pots are specially designed containers with a brush as part of it’s self sealing lid. Such items are not too expensive but hard to clean as will be necessary between fillings, short of taking the glue pot apart and re-sealing it with silicone each time. Brushes are easy to get and inexpensive.

    This is a very good general purpose adhesive for most flexible plastic or rubber like things especially cable, but unless you have constant use for it the glue will get expensive due to even in a glue pot, it has a limited shelf life of 6 months on the outside once opened. It also needs to be well mixed for the initial use, having a paint company mix it for you on a machine will be helpful. #2141 runs about $20.00 per quart thru McMaster Carr #7509a74 so it’s not very cheap - you do not want to waste it.
    Setup time is in the range of 30 seconds for a thin layer, to two or three minutes for a thicker layer this includes the brush so you need to apply the glue and don’t linger, stick the brush back into the glue pot as soon as possible this will both prevent the brush from drying and becoming gummy, and help prevent the remainder of the pot from drying too fast. The major advantages of the glue is it’s setup time and superior adhesive qualities. This is a very good glue, however if in a school you might want to verify with the MSDS data sheets such chemicals are allowed to be used or in stock. It is flammable but safe enough in use with a heat gun. A final advantage of using this adhesive is that once it’s dry it, any glue not under the tape will be safe to touch and leave exposed because it is no longer sticky. You want the adhesive to extend past the tape, the alternative option is having parts of your tape not permanently bonded to the wire since it is not atop the adhesive.


    Since this is data cable, it is not worth a major repair job to it. In addition to that, if your repair using normal methods expands the size of the outer jacket too much, it will be a snag point for the wire as it is pulled and be subject to more abuse than the repair can withstand. Also, the dia. of the wire is too small to properly apply other forms of covering to it other than heat shrink below.

    For these reasons, especially cost effectiveness verses labor, I use electrical tape atop the adhesive. If you are making a repair with electrical tape, use the best tape you can so it does not come loose. This stuff is abused and exposed to handling not sealed up within a wall box. It’s temperature and moisture exposures will be subject to more extremes than household electrical tape will be exposed to also. In other words, use 3M Super 33, there is no better general purpose electrical tape on the market for cable repair. Otherwise if the cable is to be exposed to extreme cold, use cold weather electrical tape. The Super 33 will for the most part stick well to itself but not sufficiently to the cable jacket thus the adhesive is necessary. Two to three stretched and tapered layers is sufficient in most cases as protection over the cut.

    Atop the electrical tape I apply Black Liquid Electrical tape. Frequently I will apply it directly to the electrical tape or add another layer of adhesive than the Liquid E-Tape. This takes the place of cable paint as required for splicing, but since cable paint is not generally available on the market, the Liquid E-Tape when fresh will suffice. Liquid E-Tape is available in 4oz containers with a brush on it’s lid, when it becomes a little less fresh it will not paint the cable very well but will fill holes better - see below. Again it has a shelf life, you need to ensure the cap goes all the way back on after use and don’t expect it to last once opened more than a few months. The purpose of the Liquid E-Tape is three fold. First it provides added water resistance to the tape and repair. Second it adds to the abrasion resistance of the tape and will help prevent it from coming loose or rolling up along it’s edges. Third it provides a visible indication that the repair has been inspected and properly repaired as opposed to a repair with just electrical tape covering it but no idea if it was properly repaired and inspected. If the cable is subject to a lot of abuse, it might be necessary to periodically re-apply the Liquid E-Tape.

    If the cable does not have a connector on it, often it will be easier to install some heat shrink with the above adhesive over the cut, or to slightly stretch a 3/4" expanded 3:1 or 4:1 heat shrink so it fits over the plug so it will shrink down over the cut. Expanded 3/4" heat shrink at 3:1 shrink ratio will shrink down to about 1/4" dia.

    Power Cable Repair with it’s ends off: If the cable does not have a plug on it, or it’s easy enough to remove it, heat shrink with adhesive under it as per the above method will work sufficiently to protect a cut but not a hole in the jacket. In this case you will want to apply some Liquid E-Tape into the cut to adhere it together and seal the cut. Liquid E-Tape inside of cut has the advantage over adhesive of not being as strong of a bond which if it also adheres to the inner conductors can make the insulation over them tear off and expose conductors inside the jacket as the wire moves. It is necessary to ensure inner conductors are allowed to remain independent from the outer jacket because within the cable jacket they will have different amounts of movement from the outer jacket. I tend to use red Liquid E-Tape to seal up a cut, this way should the cut become exposed again it is much easier to spot the needed repair. Liquid E-Tape does not stick that well to thermoplastic insulations such as on most Socopex type or SJT/SJE cable but will fill the hole in preventing the opening from constantly opening and closing. An alternative would be to use the adhesive as long as it does not glue inner conductors to the repair. Again, if the inner conductors are also cut you are better off not attempting to repair the cable.

    As per the above XLR repair, clean the cable jacket with Goof Off as needed than Naptha, than apply some adhesive and allow it to set up. In this case, you want to extend past the cut at least four times the diameter of the cut for proper protection of the repair. A light even coating of adhesive is better than a thick one that can become hard and crack, or even bubble up. An added advantage of the adhesive will be that as opposed to normal heat shrink that splits when over heated, the adhesive below the heat shrink once it is compressed enough will bond to the glue and not split. Above the adhesive apply sufficient layers of heat shrink to bring the repair up to the same thickness as the cable jacket started out to be. In other words, for a SJ type cable that’s two layers of ½" expanded 2:1 Polyolefin heat shrink, or possibly one of a 3/4" expanded 2:1 or 3:1 heat shrink due to it’s completed shrunk thickness. On XLR cable, as single layer is probably sufficient, but on SO and SC grades of cable, multiple layers might be necessary. It might be advisable to apply some adhesive between layers of heat shrink to prevent it from re-expanding. Avoid PVC heat shrink, it is not UV resistant and in general does not flex well or last as long. A single layer of adhesive lined 3/4" expanded 3:1 heat shrink will work best for all cuts including ones with slight holes. Basically it is heat shrink with hot melt glue inside of it which will allow it to stick to other layers of heat shrink or repairs better. Note the hot melt glue is insufficient to bond with the neoprene jacket, rubber adhesive is still necessary, but it in addition to the hot melt glue will produce a very good bond, and a tough hard repair which is very abrasion and damage resistant. It’s disadvantage is it will not be flexible so it’s maximum serviceable length for a repair is 6". Shrink tubing in general should not be used for repairs of over 8". Once the heat shrink is on no further covering should be necessary.
    Of note on heat shrink is you need to slide it into place before the adhesive has set up or you might not be able to slide it into position. Should your adhesive set up before the heat shrink gets into place, Denatured Alcohol will often temporarily allow the heat shrink to slide. Once the heat shrink is in place, allow the glue to set up before shrinking it or it might boil and create a bubble in the heat shrink. Should a bubble develop, do not puncture it, let it shrink down on it’s own. Or replace the heat shrink if it does not go away. Take that part of the heat shrink away from the heat as soon as possible, allow the heat shrink to cool and hopefully bubble go down, than continue shrinking it over the repair.

    Vulcanized Power Cord repairs in General: This method will work very safely when used for anything from 4/0 feeder cable to fixture whips - though fixture whips are better off with heat shrink repairs if not replaced overall. It is directly based upon the above book’s intent, only the length of the splice and thickness has been reduced due to flexibility needs and the fact that the inner conductors still have their factory protection over the conductors. You are not covering a splice, just fixing a cut or hole in the outer jacket.
    Step one: clean the cable as above than fill the hole with Liquid E-Tape. Allow it to set up if not come very close to drying if it is used to fill in a hole up to ½" in dia. If the hole is large and long or larger than ½" it will be necessary to use friction tape as long as the jacket of the cable is not compromised by more than 12" or ½ it’s circumference. If it is necessary to apply a thick layer of Liquid E-Tape, it is necessary to let is set up if not come very close to drying, adhesive will bond with it but will loose some of it’s strength in bonding tape to cable jacket if mixed with Liquid E-Tape and smeared on the cable jacket. This repair technique assumes 3M #2141 adhesive is used in general other than where other notes are involved for rubber cement such as rubber cement does not bond as well with Liquid E-Tape so it’s use is limited on friction tape repairs.

    Apply adhesive to the cable jacket and Liquid E-Tape. If your hole is large or a wire is popping out of the jacket, it will be necessary to apply friction tape over the hole or around the cable in pushing the wire into the hole. In the case of a hole, it will replace the strength of the jacket with a strong covering protection over it. Three layers thick of friction tape for a minimum over wires and holes. If you are covering a long or wide cut, friction tape in general can be of value in pulling back together the cable jacket and offering a strong protection to it. In the case of a wire that has pulled out of the jacket, it’s a value question as to if it is better to cut the cable at that point or attempt to fold the wire back into the cut, hope it pulls back into the cable or at least letting the friction tape protect it. On normal power cord, cutting the jacket will be the best option. For Multi-Cable with a thermoplastic jacket, likely the thermoplastic covering will not be overly adversely bonded to the Liquid E-Tape or Friction tape and the conductor will move some as normal, but not pull itself back into place if it is out any real distance from the jacket. Be careful not to apply any adhesive directly to this wire or any wires in general under the friction tape. Liquid E-Tape protected wires can have adhesive attached to it, but otherwise it is better to let the friction tape attach directly to the conductors as it will not rip off their insulation. The friction tape will be strong enough to hold the wire in it’s place and prevent the jacket from bunching up or spreading apart. Next apply a generous amount of adhesive over the friction tape. This will serve a double purpose. First it will allow the rubber splicing tape to bond with the friction tape, and second it will act as a somewhat flexible hardener for the friction tape in much the same way as application of rosin or epoxy on fiberglass sheets works.

    If you are not repairing a large hole or cut, friction tape is not necessary skip it’s step and start with Liquid E-Tape in the cut, than apply and let set up the adhesive to the jacket. The adhesive should extend at least 2" past the end of the cut, and up to 4" depending upon the cable thickness and amperage. Next apply self-vulcanizing rubber electrical splicing tape to the adhesive. If you are using rubber cement, you will need to wait for the cement to completely dry or it will burn thru rubber splicing tape and reopen the hole no matter how many layers of tape you put on it. Otherwise with adhesive you need to allow it to set up because if still wet it likely will not complete drying and might not allow the tape to adhere sufficiently or tight enough. Rubberized electrical tape will permanently bond to itself but not the cable jacket thus the need for adhesive. It will provide a water tight, and electrically intact and safe protection over the repair in sufficient thickness as required. This needs to be as thick as the cable jacket and extend for at least thee times the diameter of the cable past the cut. Normally this would mean three stretched and tapering layers over a SJ cable or more on a SO or SC cable. You stretch the tape until it either changes colors or becomes half width, and if it has a plastic tape covering over the rubber splicing tape, you do have to remove the plastic as you apply the tape. Also if you do not stretch the tape sufficiently, it will not vulcanize to itself, and will probably fall apart with time. Start at the cut and work off to one direction, than back towards the center and to the other side. Continue wrapping the cut in a tapered pattern meaning the second layer will end ½" in from the layer below it. This will allow for the cable to be pulled without snagging or flex easier. You are looking for a rounded or smooth repair. Should the tape break as you stretch it, apply the next section, start wrapping the tape again near where it broke, wrap the tape back on itself to cover the end and starting seams than continue on. The goal in rubberized electrical tape as with any taped repairs is to only have one seam - the end of the tape where it is cut exposed, where you start wrapping and where it breaks should be covered by the tape completely. After you cut the tape, stretch and push to blend the end of it into the repair so the seam well adhered and not as easy to snag. Three layers of Rubberized Electrical tape would be about the norm for SJ cable.

    Apply a layer of adhesive above the rubberized electrical tape and allow it to set up. Extend the glue 1" past the rubberized electrical tape. Apply two layers of Super 33 tape atop the glue and extend it 3/4" past the edges of the rubber E-Tape. The Super 33 will provide abrasion resistance to the otherwise too soft rubber electrical tape. If you attempt to apply more than two layers of Super 33, there is an increased chance it will with use loose it’s bond with itself and become unraveled. Stretch the Super 33 by about 1/3 it’s width. Apply a thick layer or two normal coatings of Liquid E-Tape over the electrical tape. Wait for the first layer to dry before applying a second coating of Liquid E-Tape. This will complete the repair and provide extra weather and abrasion resistance. For added abrasion resistance, you can apply a very light layer of adhesive atop the Super 33. Allow it to set up and almost dry before adding the Liquid E-Tape, this will better bond the Liquid E-Tape to the repair. With use it might be necessary to apply more Liquid E-Tape over the repair or use cable paint such as a electrician/linesmen might use if you can find any.

    These are the methods I have developed and have been using for cable repair for about 5 years now professionally. They work very well to protect the cable and are permanent. If done properly with a taper, the repair will not be overly large or too seriously effect it’s flexibility.

    Never trust anything that is just taped together as a repair. This is a temporary repair at best and possibly covering something that can be dangerous. All it takes is a little moisture, heat or exposed conductors and your wire given sufficient amperage and voltage can short causing all kinds of problems if not a fire. Proper repairs are very necessary if you want to continue using the cable without cutting it and making it into at best two usable sections. If not the above or an even more proper linesmen’s splicing covering method, just cut the cable and make what ever you can out of it. Electrical tape alone does not make a permanent repair, it just makes me suspicious. All repairs need to be inspected by trained personal looking for damage to the conductors before it should be repaired permanently than placed back into general use stock. Should you need to do an in the field repair to cable, it is a nice courtesy to provide a strip of colored electrical tape near the repair in a yellow orange or red so such a repair will be noticed after the production. An alternative method especially for feeder cable would be to apply the friction tape and rubber tape as above, than use heat shrink to form the outer protective skin over the repair.

    Brian Shipinski
     
  2. HMOcidalmaniac

    HMOcidalmaniac Member

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    wow...thats it- just wow-
     
  3. TechnicalDirector3-W

    TechnicalDirector3-W Member

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    you can say that again.
     
  4. DMXtools

    DMXtools Active Member

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    Brian does tend to get a bit wordy... but his information on cable repair is rock-solid. The bottom line is that inproperly repaired power cables are a fire hazard. The safety of your actors, your crew and your audience depend on getting it right, so the instructions have to be pretty detailed. My own advice - "when in doubt, throw it out."

    John
     
  5. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Great post Ship.

    I notice that you refer to friction tape and self vulcanizing tape in a few posts and I am not familiar with these products. I did a very quick Googl search and will read a little more about them and see if who distributes them here. They sound as if they should be in my tool kit!

    Cheers,
     
  6. The_Terg

    The_Terg Active Member

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    Friction tape is the third greatest tape known to man!

    if you haven't seen the stuff, its like electrical tape, but has a very rough and almost 'sticky' exterior. It is very similar to the stuff on the top of a skateboard, or on slippery staircases. I desperately need a roll of the stuff!
     
  7. ship

    ship Senior Team Emeritus Premium Member

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    A point of statement, I wrote the above in full expectation of others posting their methods, be it from I have been repairing cable with just electrical tape for fifty years and never had a problem, to other methods and intents in repair. Other methods are welcome, otherwise balance your insult on my concept of repair as being wacked as opposed to a realistic asscessment of your method and how it really complies with the principles of the NEC. Post away your method or criticism, but give at least the intent and reasoning of mine a chance - at least something to keep in the back of your mind.

    The cable repair methods I outlined are my own and as policy I set up over time for the company I work for. I would not mind it if other companies similar in size or profile at least looked into this method, especially local companies. This would be best for all of us. They are unique to the industry and not the industry standard as with much of what I advise or do. There is no perminant repair standard to the entertainment industry much less given the use in repairing cable jacket's nothing similar in the electrical industry beyond the use of electrical tape as a temporary fix to power cords - for the most part unless you work for the electric company. Licenced electricians are just as likely to use E-Tape on a power cord as we are. Sometimes this use of normal electrical tape works sufficiently, on the other hand my method when properly applied will always work and be a NEC compliant repair based upon all factors into it given only that I have shortened the length of the repair that otherwise would be required for a line splice. In other words, there is a world of difference between some 400 Amp carrying feeder cable I have repaired, and some temporary fix a stage hand has applied on the job two years ago and is now coming loose in a very gummy way. The most limitating factor of my system is the Liquid E-Tape outer covering. It does wear off with abuse, but I do not have a source for cable paint even with industrial electrical suppliers nor know if it will work better. Occasional re-application of the outer covering is needed infrequently, but at least with it's use it fits the main purpose in indicating what you have inspected and forms that cable paint like outer coating over the electrical tape as definately required by the NEC. Who knows who just taped over a section of cable otherwise or how safe it is. Your repairs look just like Buck Tooth'ed Bob's.

    I understand that what I have laid out is outside the bounds of normal repair unless you work for a large company with time, manpower and budget for real repairs. Again, if you cannot repair the cable properly and perminantly according to both what's necessary to keep it installed for as long as the cable lasts, Be absolutely NEC compliant, much less what will stand up to use, you are much better off just cutting it even if it's only a slight accident from a utility/matt knife. Cable looming is the practice of taping together bulk amounts of cable for shows that are headed in the same direction. It makes life easy if you can loom your cable together before the show so all you have to feed into that direction is one instead of multiple cables. This saves time but requires cutting the taped looms afterwards. One slip or nick on a cable jacket often is sufficient to force you to repair the cable given the stage hand was not "too cool" to do any such thing and not courtosy mark his screw up. A simple installation of a hook blade into your utility knife will prevent 90% of all such slashes to your cable jacket. This for me is almost at the point of supplying all tours with such blades and making the crew chiefs issue them to the stage hands. (Wonder how well that would go over with the I know how to use my knife IA types especially if they are using their multi-tool toy for their professional job.)

    However in the real world, where time is short and budgets for proper working on cable is even shorter, this method most likely will not be adopted. Still such things as the adhesive and cleaning the cable first, even if rubber E-Tape and Friction tape are never used, such a tip brought to the table will help tremendously in making a perminant repair. Had I not been at times tasked with 8 to 16 hours a day all week long in repairing cuts to cable, I will not have thought or put as much effort into making a real perminant repair to it. I also will have not looked into other knife blades that are safer for use in de-looming the cable. (See far below.)

    You don't have access to a spray bottle of naptha, that's fine, just clean the cable as best you can than apply the adhesive. If you can't take the time or effort, much less stock small tubes of even bike repair cement at a minimum to bond even electrical tape to the cable, at least you can take with you a standard of not attemtping to repair or fix power cords with the copper conductors exposed. Since the inner conductors move within the jacket indipendant of the jacket, any even well intended repair you attempt to the insulation over conductors is far too easy to fail.

    For note, the origional question on cable repair was to perminantly installed data or sound cable and not to line voltage power cable. The soldering methods will work to a certain extent in a perminant install, but not for anything that is moved or used in different locations. It is not advisible for any other purposes especially power cords. A normal stage hand will taper his electrical tape repair over the cut. This can be fine for a perminant install also or for gear you don't give a crap about what such a repair years from now says about your repair or skill level. Certain even taped repairs I won't mess with because if not used, they do hold up. My repairs are for active stock which is constantly abused if not even submerged in sea water at times.


    As for what is it? McMaster Carr to the rescue again http://www.mcmaster.com/ in being the standard for stuff available or in this case, me giving you the part numbers for you to look up and see what products I talk about.

    Punch in the part number or copy it, than read the description, or go the the PDF of the catalog page and read further information about it especially in the header to the product. The most limitating factor to them is that they don't always list info about the manufacturer unlike Grainger. On the other hand, I'm yet to find a crap product come out of their catalog so it's safe to assume that if it makes it to the catalog it has been playtested by some buyer for them beforehand in keeping up their standards for quality.

    Friction Tape: 76465a1
    Rubberized Electrical Tape: 76455a18 amongst many sizes and styles of both peel off liner and non-peel off liner.
    Glass Clot Electrical Tape: 75455a17 (From the Zip Cord/PAR can post)
    Liquid Electrical Tape: 76425a22 (Specify the Color)
    Super 33+: 76455a12
    #2141 Rubber Adhesive: 7509a74
    Glue Pot: 7465a11
    3/4" Adhesive Lined Heat Shrink: 7761k56


    De-Looming friendly Knife Blades: 4927a18 (available in smaller than 100pkg containers cheaper.)
     
  8. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    Eg:
    Core 1 --------xxxxx-----------------------------
    Core 2 -------------------xxxxx------------------
    Core 3 ------------------------------xxxxx-------


    Hey Ship--believe it or not I once had a cheap boss who did this kind of splice with 6/5 feeder cable that got cut... he used e-tape and copper lugs and a ton of friction tape.. :!: :!: :!: 8O 8O 8O

    ya..I know...believe me I know....some people...they are just here for us to look at and walk away in amazement. :?


    awesome post....simply awesome... you rock...
    -wolf
     
  9. ship

    ship Senior Team Emeritus Premium Member

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    Friction tape is a cloth tape that is covered in a combination of tar and rubber. It long predates the invention of plastic, much less electrical tape. If you live in a house or theater that pre-dates about WWII, than it's very likely that not only will your connections be soldered, but they will be covered in friction tape.

    Friction tape has a life in the electrical industry now as being the volume or bulking up item used for strength and thickness to splices. It's well and generally available as with rubber splicing tape at almost any home center or Ace Hardware. Why and who buys the stuff besides me and old timers, I don't know as it's use is limited. It tends to peel or not adhere to itself very well afterwards.

    Friction tape otherwise is what it states. In the old theater industry with Union Connectors, it made a long time come back in making up a strain relief for cable sized smaller than the opening of the plug. It works well for this and with time will loose it's gooeyness and just become cloth tape on the exposed surfaces. The idea of using friction tape is that it grips well to itself and because of it's rough texture, when compressed under a strain relief, it will grip cables well.

    It also is less likely to leave a residue on the surface of the cable than electrical tape so for this reason many stage hands use it for general purpose work such as taping up a bundle of cable. Good stuff for this purpose because it's fairly strong and damage resistant. It is also for the most part less effected by the heat than cheap electrical tape.

    Further use for it in my case is between heat wire and the fiberglass sleeving over it inside a modern Bates plug's strain relief. This when compressed between cord and sleeve will prevent the sleeve from pulling loose from the strain relief much better than the plastic to fiberglass over fiberglass gripping abilities normal to a fixture cord in a strain relief. This for me is a compromize, I would prefer to have a few layers of friction tape above the fiberglass sleeve also to prevent the strain relief from cutting into the fiberglass, and prevent too tight of bends to the cord at the plug, but it when fresh does get gooey and attract dirt. For this reason out of compromize I use it between layers inside the cord. Do not use it at the fixture, it is combustable. Use fiberglass electrical tape instead.

    Anyway, I hope it takes some of the what is it out of friction tape. This is very similar to what is used on hocky sticks, only it's impregnated adhesive and natural, verses handle covers are only coated with the adhesive and not UL listed for electrical work, nor will it work as well.

    As for line splices, cheap is cheap. Copper splices with all sorts of coverings is known but certainly not what you want to stake your career on what happens to it when it sits in a rain puddle during a show. 6/5 wire, that's about 60 to 85 amps in current. Hmm, should create a nice spark if not done. Walk away is no doubt the only way to deal with such circumstances. My shop manager just bought a replacement metal cutting band saw for the shop. It has a oiler but he refuses to use it because he thinks it's both going to rust the blade and dull it. I agree in walking away unless there is a hope I can get thru to the idiot, much less I am given the chance to improve what's standard. Walk away is unfortunately often necessary no matter what the consiquences unlike with our lighting brother the electrical industry where stupid things at least can fall under question.

    I'm working on lamp bars this week. Another you are doing what' type question. At least with my re-wiring and improving upon what's done they should at least be safer and hold up a little better with use inspite of still being against code for a lamp bar with out a division between wiring area and seperate track the fixtures are supported from. Hmm, bolt inserted into the cable area. Na, there is no chance such a bolt could rub wrong much less cut away at the insulation on the wire. Much less the archaic way the tails were installed and with what crimp tools the terminals were applied with. Need just that extra inch of wire out of the lamp bar, you can, you can also pull the wire free of it's crimp terminal. That's all another posting however.
     
  10. Nephilim

    Nephilim Active Member

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    Wahey! I just recently had a really awful 'whip' (I call 'em tails ;)) splice fall apart on strike this week - guess who's ordering a crapload of new tails? Yeah. Also we have some older instruments with totall cracked jackets; looks like I'm in for a complete wiring check. Goody.

    Hell if I'm not printing this thread out :)
     
  11. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    Ship,
    Just a quickie question--Liquid e-tape--is this the same thing as the Scotchcoat?? I don't recall scotchcoat being in any color...just curious.

    FWIW, I have some great samples of dead-cable..cable that has glazed over, that is "pourous" and showing cracks..and some cuts of cable that has gone totally toasty and the jacket splits or just pops holes in a pretty spiral pattern for the length of the cable due to excessive age and heat. Quite fun to see...

    Dave--if I digital photo some of these--can you post them to this thread so folks can see the differences in the cables so they can identify BAD cables?

    When I repair cables--it can vary to the length that I will go to for repairs based on time. In general--a pair of round cable cutters to score the jacket--or a quick-knife works too in a pinch, and a pair of wire strippers and a screwdriver...however given neither of those at hand, I've been known to use dimes for flat head screws and I also keep a sample key on my keychain that does nothing and works on no door lock--I have it cut to "points"...this works on most phillips screws. You can pick these up for usually free from key cutting shops..cause they are samples that do nothing or didn't work for a customer. Same for dogtags working on screws... As for stripping wires...in a pinch without tools, this is where I use my thumbnail. Over the years I've developed a good thick thumbnail..it cuts into the jacket and rips off the insulation in a pinch..everything from data cable to 12guage. Wish I could do the black heavy jacket too like this.

    Ship, What is your opinion on soldering connections to the spade lugs toi the wires for stage connectors? I've seen some folks solder them...seems like an OK practice.

    -wolf
     
  12. Nephilim

    Nephilim Active Member

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    I have two 360s with long, long tails that have done exactly that, if you want pics let me know :D
     
  13. cruiser

    cruiser Active Member

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    I think from memory that post was 4,094 words and 4pages long..... Got a mate who is a computer nerd and never seen a post soo long and insisted on word counting it!

    fantastic information btw ship!
     
  14. ship

    ship Senior Team Emeritus Premium Member

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    Invalid_ Session again and I did not copy before posting. When will I learn. At least this one is being re-written with spell check than posted as one.

    Only 4,000 words? Send the nerd over to the Soft Flat construction description, this one was short. Unfortunately for me I try to be thorough and give tips which makes it long. Question is if in being so long those it’s written for finish reading it with any interest or help. I hate short and not specific enough answers yet if the answer is buried in text it might not be any good. Bear with me or ask for cliff notes on parts if it helps because writing less does not seem to help enough as a goal. Even I never got back to finishing the editing on the soft flat notes.

    Anyway a simple question of my own that I don’t remember how to convert. It’s a story problem. A 5% change in the voltage applied to the lamp results in a 2% change in color temperature. What would the effect on color temperature be at 1% change in voltage? Simple I realize but it’s not computing - my math teachers are no doubt rolling over in their graves right now.

    On Wolf’s posting and question, let’s open it and his wire stripping techniques up to all the electrician’s out there. As might be inferred my little electrical world while possibly optimum is more than what most others would consider acceptable practice. So me saying nay might be a little out of sink with acceptable even if expected. I would also be interested in Wolf’s reasoning for soldered crimp terminals being OK. There are many practices and techniques out there just as there are many electricians with different viewpoints and practices. All who do electrics have a voice in what’s acceptable or not.

    We all might also work on a Wall of Shame type posting of photos. Eventually I’ll get one of them cameras also. I have some gems collected up too. My latest arrival is something like a 20 amp transformer from 220 to 120 volts off a Euro Beam Projector. The thing is huge and heavy making it hard to store, but it’s terminal block and all wires involved must have had quite the fire because it is uniquely trashed.


    First a note on laziness and old school stripping techniques. Wolf it’s about woodshed time, can that coin or key provide sufficient or proper torque on the screw terminal? If it can than great but such things are not my way. Though I did do this technique at some point last week on something I know it was not electrical. It was probably something like a scroller opening knob. I’m too serious when doing electrical work. Given such an air I have about myself, when I screw something up the consequences are not only frequently more dangerous and usually also more something I’m not allowed to forget by my peers. That’s good in a way, it keeps me on my toes and on the up and up with wiring. My value is in that I always do the job to the best of my abilities and don’t cut corners with the wiring even if safe enough. Were I to slack off, I would not have earned the cush job and I would still be climbing ladders. You do what you have to in a pinch, but I thought that pinch was what the Leatherman was around for. Enough soap box. Wolf is a sound tech person I would trust his ability, I just don’t cut corners but I work in a nice warm shop with the repairs brought to me or when in the field have at least a full tool bag plus belt, if not full road box. I know what to get Wolf for X-Mass now and it aint’ a shiny nickle because his name is not Bobby or was that old song Tommy as the kid with one. Just pulling your leg.

    You use what you need to when you have to, it’s not preferred especially by me but your posting this is not a request from absolution from the wise BShip as it were (pronounced Bishop) as the back aisle guys are beginning to call me due to my signature on most of the cable they sling all day long which I constructed.

    As for stripping wire with medium 1" capacity cable cutters or knives, I hope to convert you one day to using dikes to strip the cable jacket. Much safer and it works for all types of wire up to #2 Feeder cable. In a pinch for insulation especially on solid wire I’ll use my linesmen’s pliers as per the old timer technique, just have to be careful how deep I cut into it. Otherwise for stuff like 12/3 Zip cord I get out my electrician’s knife to peel away some of the insulation around the hot and neutral so it will fit into the terminal surround. The cutting blade on a Leatherman works effectively like linesmen’s otherwise, perhaps even easier. But I own somewhere around 7 pairs of wire strippers of different types in addition to at least three pair I bought for the shop tools I also store near by at the guest work table. On the whole, I have grown too accustomed to my 3.6v cordless screw driver and Klien electrician’s tools and feel naked doing work without them. Especially my insulated wire strippers of a style they don’t make anymore c1998 as stamped on the handle. Spring activated and very comfortable in the hand. Only problem is I have developed choking up on the handle to the point one finger finds it’s natural position on the other side of the hand guard. This is fine except if I’m working on live circuits at which points I have to constantly remind myself to hold the tool properly at the same time as reminding myself it’s live wires and focusing on that part of what I’m doing. Anyway, I feel naked without those tools I am so used to having around. Done the dog tag trick while in the military, it works well. As for my nails, my hands slip into or get ground up by sharp things too much and they break chip or dent and don’t last long because of it. You can tell if I’m not busy for a while, I have long nails at those points.




    So my opinion of soldering terminals. I assume you meant crimp type ring terminals because what you wrote would be a flat lug that’s crimped or set screwed into place that you mount on the end of a feeder cable to connect it into a service panel or bus bar. Even a spade terminal - as in the male quick disconnect would not apply to stage pin plugs. Instead I take it for granted you mean a 12-10AWG ring terminal with #8 Stud hole either in the flag terminal version - ring terminal off 90° from the wire hole, or normal version depending upon what type of plug you are using, Union or Rosco/Pinecrest style.

    I would assume that the solder technique comes from old timer practice with the original stage pin plugs that were not designed for ring terminals and you had to either tin your wire into a circle around the stud, or attempt to find the wire supporting washers if you wanted an arc free connection. I have to admit I would be hard pressed to find a wire washer. It’s also very rare I see any even on ancient plugs.

    It would also be about standard practice with most in doing the pins for Socopex plugs and seems to work just fine as long as it’s properly applied. Otherwise if a cold solder or a short, the wire will come loose from it’s pin. Can’t exactly tin much less solder a 12ga wire to a terminal with a normal crap soldering iron either. You have to have either the Big Bertha iron or a variable temperature one that will go up to 800°F. Even than it’s a question of fluxing or not fluxing and using only the freshness of the wire and the solder’s acid core to do the bonding. Flux has the greater likelihood of getting the wire too hot and melting or at least making the insulation on the wire loose it’s insulating properties. But in soldering the ring to the wire don’t you also tin the wire and is not tinned wire less flexible? Granted 12ga wire is fairly strong, but with use and movement within the connector it’s possible to break where the tinning stops.

    But for me that’s all a moot point. First soldering stage pin terminals takes lots more time than a proper crimp tool will take and we are talking about a 12-10ga terminal meaning the hole is set up for a 10 ga wire - 1.⅔ the size of a 12 gauge wire. In other words, unless that terminal was also crimped you are using a lot of solder filler, filler that can melt should the pin get warm or there is a short. This would have the problem of the wire pulling free and being a live wire floating around inside the plug or staying in place forming an even higher resistance heat source than the pin might be giving off due to the now loose contact with wire to crimp terminal. Also in the heating of the pin situation, if you blob some solder onto the ring part of the terminal, it will prevent the screw from clamping down with an even pressure around the ring meaning all the current can be going thru the solder. This could be enough in a overload to melt the solder and become a high resistance loose screw contact point further causing heat and problems.

    It might be possible that if it’s both crimped to reduce the size and soldered, the technique you cite comes out of a solution to insufficient crimp tools being available and the wires otherwise pulling out. I can see that. On some things such as a 22ga wire into a 22-18GA ring terminal even if folded over, the pressure from the crimp tool might be too much for the normally made that way tinned wire to handle without breaking at least a few strands. Also it’s really hard to remove crimp such a thing sufficiently with a balanced pressure all around the wire. Solder will help keep the wire and all of it’s strands in place. I also amongst other specific applications will crimp and solder a motor cable whip given ours have both a wire rope core for strength and a ground wire going to the center pin of the 7-pin Veam CIR plug. Something about 1/16" wire rope when crimped with a 16ga copper wire makes me want to help reinforce the copper as much as possible due to the crushing pressure involved with crimping the wire rope to the pin. For this like with all Socopex pins I’m using an expensive 4-indent crimp tool instead of soldering. It does a much better job of providing a balanced pressure on the wire while it does not damage the pin.

    Anyway, if the crimp tool is insufficient like with all store bought do it all insulated jaw or lame teeth uninsulated crimp/multi tools, than soldering the crimp might be a solution. As I said I’m in lamp bar re-wiring heck right now. The main cause for me having to completely rewire more lamp bars than I have time for, much less the Leko prep people to spend so much time repairing them is because people used un-approved crimp tools on the butt splices and the wire came out of it’s splice terminal. Unfortunately solder would not work for insulated terminals, heat shrink might but it is not very abrasion resistant or thick in wall. Use a proper Stakon type crimp tool with real teeth to it, and sufficient pressure and there is no problem or need to solder your crimp terminal. If you grind off the cutting blade on the tip of such tools - the Klien 1005 & 1006 being prime examples, than without the cutting blade, such tools will also work on flag terminals - as the only tool that will crimp the terminal but not damage the flag part of it. In the end when it became apparent that not everyone was able to apply enough force to the crimp tool, I bought a ratcheting crimp tool that makes it not possible but to crimp all the way down to release the handle. Wire roped it to a hefty steel plate so it does not end up missing but is still portable.

    Anyway, that’s my thoughts, sounds like the solder solution is a quick fix to a improper application problem. I would not like to use it, instead I would buy a proper crimp tool such as those above which are made by a bunch of different companies to the exact same design or a Vatco #1900 multi-tool. Grind off the wire stripper cutting blade, it is a lame wire stripper and dangerous when cutting bolts since it frequently will cut into the palm of your hand. But for a crimp tool, it is very comfortable to use. It’s jaws are a little small in thickness but sufficient. Plus the less thickness allows it to crimp with less pressure.

    A good test I have written about before and I still use once a year to impress upon the new kids is the hanging from your crimp test. Given my concerns with tinned wire plus strength, you might test the strength. It might be sufficient in other than a short condition, but will defiantly show if you are using a proper crimp tool or if your pressure is too light or too much.
    Same technique. Have the new kid use their Ace Hardware special crimp tool crimp some ring terminals onto some 12/3 wire. Even allow them to put extra force into their crimp over what they would normally use. Than use the Stakon or Vatco tool to crimp some ring terminals onto the other side of the cord using normal pressure. Screw both ring terminals to a piece of plywood or stud mounted to the wall using #8 wire gauge screws. (Number 6 screws have a sheer strength of 40# each and will be possible to break during the test.)
    Next give a tug on the newbie’s crimped wire. Most likely it will pull right out of the terminals. If it does not, climb up the wire. 12/3 wire will support about 150 or more pounds before it breaks. If the wire does not slip out of the crimp terminals at that point, give it a bounce while hanging. I have never had a un-approved crimp terminal survive this far, they all slip out. Than have the kid climb your cable. If done properly - cross your fingers, the crimp terminal will hold and be every bit as strong as the wire. The first thing to fail would be the ring itself and a #8 stud ring terminal is fairly strong.

    If you wish you can use steel high temperature ring terminals for this if concerned about the ring not standing up to the test. This would also be a good test for a crimp tool because they are even harder to crimp sufficiently. - the other reason I bought the ratcheting crimp tool. Again on it, I don’t use the insulated crimp teeth. I would rather displace some insulation from a tooth penetrating the insulation than have a flattened out crimp but something still the same cubic volume. A jaw from a crimp tool penetrating the barrel part of the hole will reduce the amount of space available inside the crimp instead of just crushing the berrel.

    This is a realistic test of the stress wire in a ring or any other crimp terminal might go through in it’s lifetime especially if it has a bad strain relief.
     
  15. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Ok - don't know what happened here but I seems that everything I did yesterday is no longer here. I noted that the site was down for a while so I guess that has something to do with it.

    Ok – here goes:

    Vdiff 1 = 5%
    Coldiff 1= 2%
    Vdiff 2 = 1%
    Coldiff 2 = x%

    This means that if 5=2 then 1=x

    Therefore:

    x = 2 x 1
    ------- = 0.4
    5

    Therefore a 1% change in the voltage applied to the lamp results in a 0.4% change in colour temperature.

    Hope this helps,
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    Ah' now I remember Y/X = y/x type of thing. Knew the formula, just had a mental bock as to how to answer it. Thanks, noted and installed into my notes.
     

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