2) Meter the cable, install it on a wiring test circuit, or use a gam check.In metering the wire you want to check not only for continuity but for shorts between pins, and how well the plug and connector fit into the test circuit. Testing cable on a line voltage circuit when the cable is though to be bad is probably not smart. Testers should be low voltage battery operated.
3) Examine the plugs for visual signs of damage or over painting of the pins. Are all the screws in place, is the strain relief in tact and clamping sufficiently. Is it damaging the jacket of the wire by cutting into it, or has it failed exposing conductors out side the plug. Are the pins bent out of shape or if slip/stage plug is the gapping of the pins correct?
4) Examine the jacket of the entire cable, look for abrasions and cuts, fold marks, burnt areas and knots inside the jacket. Flex the wire at the plugs or any heat damaged areas. If rubberized cable, there should be no visual signs of the wire cracking as you flex it or the insulation is not doing it' s job due to dry rot or burning. Examine if the main part of the wire still has its' factory printed description code on it or if it's more warn off than on, note the wire gauge, and type. This is a good indication of age and when to get rid of the wire.
5) Examine the marking or identification tags on the wire if any. Is it readable with the theater name and phone number, is the length marking tape color still there etc. Is the cable tie or tie line in good condition etc.
6) Remove any black electrical or other tape applied to the wire. This is used for a temporary field repair of the cable jacket and is not permanent. Any time you see electrical tape covering a section of wire you should be suspicious of what's inside. Take it off and examine what's inside for safety and permanent repair. Use of a Special Products #Nt2267
Cable Slitter available from Specialized Products
http://www.specialized.net/ecommerce/shop/frameset.htm or Jensen Tools
http://www.jensentools.com/ will allow you to safely cut away one layer of tape at a time without also slitting the cable jacket further given practice. Otherwise, do not use a standard utility knife blade to cut the tape from a jacket. It is very hard to control the depth of cut. In place of this tool, or for cable de-looming use of a Stanley part #11-961 hook blade in a Matt Knife/Utility knife will allow you to hook the cutting edge under the tape and lift it as you pull it to cut instead of slitting rom above. Both tools function as per a sewing seam ripper in cutting apart a team without harming the fabric.
7) Mark any bad areas you find on the jacket with yellow, orange or red spike tape in a simple stripe so as to make it easy to remove and not waste tape. Mark the bad cable with yellow, red or orange tape over the male plug of the cable, and remove it from service. It is also frequently easier to simply cut off the offending end or cut it at the break, than also cut off the male end of the cable to ensure it is not used. Cutting off both ends in the case of a bad installation of a plug is probably a good idea to make sure both ends are later installed properly instead of just the end that is known to be bad.
(Repair of the cable Jacket)
Examine any cut portions of the wire. If those cuts are deep enough that you can see copper conductors thru them, cut the wire at that location do not try to repair it no matter how much the cable is worth. If the cut or abrasion is not exposing inner copper conductors and does not take up more than 1/3 the circumference of the jacket or extend linearly for more than 3" it is safe to repair. If the cut takes up more area than that, the cable jacket will not have sufficient strength in going around the cut and it will pull out of any repair cutting further. When in doubt, cut it.
Method one, for less valuable or smaller data cable:
After deciding the wire is safe to repair, clean the area with Naptha so adhesive will stick to the wire. Glue does not stick to dirt. If there is adhesive goo remaining from any tape, use of Goof Off to remove the adhesive will be necessary. Make sure you clean the wire with Naptha after Goof Off or future adhesive will not stick to the solvent. Apply rubber cement or rubber adhesive to the area of the cut and beyond it by at least the length of the cut to each side. 3M #1300 Rubber and Gasket Adhesive is the best adhesive product for use because it will stick to both thermoplastic and rubber cable jackets, and let you apply various materials to it. It also won't melt thru rubberized electrical tape see below, but needs a glue pot for storage or it will dry up all too fast. Read the directions for the type of adhesive you use. With some adhesives, you need to wait for it to dry before you can use it, with others you need to wait only until it sets up and is tacky. After that it won't adhere the tape to the cable. In the case of rubber cement such as the glue for repairing bicycle tires, you must let it fully dry or it will melt thru the tape applied to it when stretching it during application.
Apply two layers of 3M "Super 33" electrical tape to the cut. Use of any other tape is not recommended, it will not hold up to temperature variations or abuse. Start your taping slightly inside the end of the adhesive applied area so you can cover it's start with the second layer. This will allow as few seams as possible exposed. Apply the tape with a stretch to it or it's not going to stay or be tight. Should it break from stretching as you apply it, make sure and cover any seams you have made with another layer of tape and continue on. Complete the tapping by wrapping the tape back on itself slightly in from the end so the seam is on the tape and not directly on the cable jacket. Cut the wire with scissors or it will not lay flat. Rub or work your seam into the tape below it. Finish by applying a thick coat of Liquid Electrical tape over the electrical tape and cable jacket adjacent to the tape. This will serve two purposes. First it will further seal the tape against moisture and abrasion and second it will give a visual sign that this cable repair is in a area that has been inspected for safety and professionally repaired.
Method Two, for cable with the connectors or plugs removed: The best and most permanent repair method requires at least one plug to be removed to apply it. Heat shrink when properly installed, is 100% efficient and the most abrasion resistant. However if it is not properly installed, it will loosen up and cut when abraded or flexed. Depending upon the thickness of the cable jacket, and the amperage it is expected to have going thru it, you might have to apply a few layers. If this is the case, tapering the layers from inside out is best to provide as few seams at the ends of the repair as possible and tapering your repair or making it a few gentile steps instead of a single large one that will get caught on everything. Adhesive lined heat shrink while more expensive is also more advantageous to use. Follow the above steps in examining and cleaning the wire. Also follow the steps in applying adhesive to the area of the repair. In this case, adhesive needs to be applied evenly and not overly thick or the adhesive will create bubbles in the heat shrink as it comes to a boil below the heat shrink. Even with adhesive lined heat shrink, you need to apply rubber adhesive because the hot melt glue used does not bond well to rubber.
Use a heat gun to shrink the heat shrink, open flames are hard to control temperature of and you might over shrink the tubing causing it to cut, burn it, or even start off a flash fire with the adhesive. Watch the heat shrink as you heat it, you want it to adhere to the surface but also do not want it to get overly tight or it's shrinking strength will cause it to rip as it shrinks. The shrink ratio as opposed to the strength of the plastic is many times more. Heat shrink will continue shrinking a bit after heat is removed, take this into account. It is better to re-apply the heat and further shrink the tubing than over heat it. The adhesive if applied in a normal amount will adhere the shrink tubing to the rubber and prevent if from shrinking further or splitting if over heated in most instances.
Another note is in the heat shrink itself. Use the shrink ratio which is part of the specifications on all heat shrink as well as it's stretched and shrunk dimensions to figure out what you need that will most closely conform to your needs. It's available in 2:1, 3:1 and 4:1 shrink ratios, and 2:1 heat shrink is the most common. While you can use 3/4" 3:1 heat shrink to shrink down to a 1/4" cable jacket, it will be very thick. This could be important for a repair when you need it to fit over say a XLR plug, but will also leave a thick seam where the heat shrink starts and not be very flexible due to the amount of plastic shrunk. This could also be a good thing in offering more protection to a cut. In general practice, 3/8" 2:1 shrink tubing might be more advantageous to use on 1/4" cable. Heat shrink is available in sizes up to 4" dia. that will easily fit over the end of a Male Socopex plug and shrink down to a 1" cable dia. However if your wire is slightly smaller than that, it's not going to protect much of anything and it costs about $10.00 per foot. Knowing the shrink ratio of the tubing you are using is the key both to using it properly and cost effectively. Also do not use PVC based shrink tubing, it is not flexible enough for permanent use without cracking and splitting. Once this heat shrink is on, it's a permanent fix as long as it's glued down and no future work is needed in keeping it in place as designed.
Method Three, the modified linesman splicing technique:
This method is waterproof, electrically sound and permanent but not as abrasion resistant as the original cable jacket or shrink tube method. It is however much easier to apply at the center of a long length of cable especially when you cannot remove the plugs. Re-application of the electrical tape and Liquid E-Tape at some point might be required because it can wear off. Hopefully by that time, the cable will have served it's useful life. If adhesive is not used with it, this is no better repair than electrical tape – the splicing tape will roll and cut. If electrical tape is not use, it will cut and abrase. All steps need to be followed without modification.
Tapering your splice/repair is also key in addition to keeping it small. For instance, on a 3/4" linear cut, you want 3" to each side of the cut cleaned, 2 to 2.1/2" to each side with adhesive applied, 1.1/2 to 2" with rubberized electrical tape on the outer layer, 1.1/4" to 1.3/4" of tape on the middle layer and 1" to 1.1/2" on the innermost layer. For Electrical tape, it wants to have it's layers extending ½" past the rubber tape, and the Liquid E-Tape past that by ½". This ensures that the bulk of the protection over the cut is over the cut but where it's not needed it is not there and getting in the way as the cable is pulled and rubbed against surfaces.
Clean the surface as per method one. Apply red Liquid Electrical tape inside the cut. This in rubber wire will adhere and fill the cut area and prevent further damage inside of it. At the same time, it as opposed to adhesive it will allow the insulation of the individual conductors to move and flex as needed. On thermoplastic cable, it will not adhere the cut but will fill it's opening in preventing a kink. Red Liquid E-Tape is used as a visible sign should the tape be removed by accident, that there is a cut. Allow the E-Tape to set up before continuing. Apply adhesive around the cut and to the extent of the repair area you need to apply it. It's tempting to try to glue together the seam, but if that glue also adheres the inner inside conductors to the outer jacket, it's very possible as the wire moves within the jacket, and it does, that the copper wire will rip out of it's insulation. That would be a bad thing.
Should there be a knot or kink in the cable where there is a large gap that needs filling especially with thermoplastic wire, or a conductor that is sticking outside the jacket in the case of a knot, you will need to protect it from future abuse if not cut the cable, or your repair will eventually fail. To protect the wire sticking out or a large opening in the jacket, apply friction tape over the area of the cut. (Gaffers tape is not UL listed for electrical repair.) Make your repair tight and solid but don't get too thick in wrapping. Taper it as best possible, but going over six wraps in the area is probably going to be too much or get too thick. Apply more adhesive over the friction tape, this will soak into the friction tape and make it have a tough solid shell much like fiberglass or dutchmen seams in protecting the area, and allow the rubberized electrical tape to adhere to it.
Once the adhesive is set up, apply 3 tapered layers of rubberized self-vulcanizing electrical tape over the area. Start with the rubber tape near the cut and stretch it to about ½ width as you apply it. Many tapes will change color such as turning silver when tight enough. Unless you stretch the tape as you apply it, it won't adhere to the surface applied to. Once applied, self vulcanizing tape does just that, it physically bonds with the layer below it. (You also want to remove the plastic covering on the tape as you apply it.) With this tape, you want to cover your seams or ends so if you break it as you apply it, rub/work your end into the layer below it and stretch it as needed to blend and adhere it below. Than start with a fresh section beyond the seam, work it into the layer below and work backwards to cover the seam from the break, than continue on covering both the ending and starting seam. Remember, if using rubber cement, if it's not dry, it will melt thru the tape and cause a large hole to open up that will eat thru successive layers. Be careful not to get rubber cement into your hole or it will as tensioned by the tape push still liquid cement up into the tape causing the hole to re-open. Rubber cement will also act as a solvent to the red Liquid E-tape filler and thin it out causing a mess. Rubber adhesive depending upon it's composition might also have these problems thus unless using 3M #1300, testing your adhesive and how well it reacts to rubber electrical tape is required. End your rubber E-Tape wraps by stretching and working your seam into a layer below. This repair is now 100% water tight and with 3 layers of tape as modified by the thickness of the cables original jacket, is electrically protecting the wire as well as it was before the cut.
Apply another layer of adhesive over the rubber electrical tape and apply two layers of Super 33 Electrical tape for a abrasion or friction resistant coating on the rubber. It will also seal in the seams from the edges of the tape preventing them from rolling up with use. Note that with each successive type of tape applied, you also need to re-apply or expand the coverage of adhesive to a new further out of the covered area of the cable jacket so the next layer of tape adheres directly to the jacket and tapers in thickness over the repair. In this final coat of tape over the cut, if you apply more than two layers of electrical tape, there is a chance that one layer will come loose and break down the effectiveness of your repair. If you apply less than that, it won't protect the cable from abrasion enough. Apply one to two coats of black Liquid Electrical tape over the Super 33 to further protect it from abrasion at the tapes edge seams as they wrap the cable. This will seal in the tape wraps and again mark the cable as being looked at and repaired safely.
(Installation of Plugs on a Cable:)
After examining a plug already mounted on a cable, you decide it needs work, remove the plug. Carefully re-bend any prongs that are out of alignment, and sand with fine grit sandpaper no more rough than 150grit, any pins with paint or scum on them. Use a pin tool to service the gap on Stage/Slip plugs as needed. Replace any plug that is not serviceable, it's worth the money. Some notes on plugs: On Edison plugs, use of old style plugs with a open face sometimes covered by a cardboard cover is against NEC and most local codes. They must be replaced. Using a plug as an interconnection device such as a Twofer or stringer is also against code but we will get into that below. Use of a plug to make an adaptor to a different style of plug or wattage/voltage rating is allowed only when stepping up to the next rating of plug and not with large leaps in wattage such as a 15 amp to 30 amp adaptor. There are some very special exceptions, but in general you should not be converting 120v to 208v in an adaptor or more importantly the reverse of it. You should also not be making an adaptor twofer of sorts that will allow you to pull two hot legs of power in making for a female 208v receptacle. Also, your plug is not an interconnection device so tying or bridging one terminal to another, is not allowed. Removing the ground from a plug constitutes modifying the plug and is against code. Including a grounded plug or receptacle on a cord without a ground is also against code, instead you need to be using a polarized two pin plug. (Note on zip cord, the ribbed side is the neutral.) As for using a stage/slip plug for un-grounded conductors, that's a grey area. If you remove the ground pin as is an option, your plug is not polarized. If you leave it in, it's misleading. It might be preferable to cut the pin short and sand it round at the tip to keep the polarization of the plug, but make it known the plug is not grounded. This modification while against many rules on modifying a plug, at least would fulfill the polarization need for screw or pre-focus base fixtures such as on a Fresnel or a table lamp using a standard incandescent bulb. You don't want the hot lead to go to the screw or outer shell of the base. This is because in changing lamps, it's possible to touch the outer shell of the lamp and get shocked. In theory, the neutral wire carries no current and is thus the one you want to be touching if anything live by accident. This is especially important where single contact bayonet lamp bases are involved. When not insulated properly or where "Mars" lights or various power transfer rotators are involved, many send the return neutral circuit thru the frame of the equipment so as to save money on the cost of brushes and isolated power transfer gears. You don't want the hot going thru the frame even if isolated or double insulated. Since the pin is not used on a Slip plug, there is no need for it to extend past the other two pins in connecting it first to power as is another code rule. In the case of two pin lamp bases such as on Lekos, it does not matter which pin is hot thus the ground pin can safely be removed given the equipment cannot be grounded as it should be.
Remember, you do want to use polarized plugs on Edison style plugged fixtures used for the stage or industrial setting. Use of "Add A Tap" type plugs in the theater while easy and fast on zip cord should not be done. Commercial grade plugs are required for theatrical applications. Avoid on an Edison style plug, ones with metal shells or metal strain reliefs wrapping around a rubber body of the connector, they are not rated for heavy duty use and have inferior methods of attachment to the wire at the terminal. Eagle as a brand is not known to produce a commercial grade Edison style plug. That said, should you need to use this type of plug where the individual conductors are put into an exposed clamp, you might want to install the stranded wire into ferrules so they can receive the proper tension and not work their way out of the un-shielded clamp and short between contacts.
Installation of plugs on cable steps:
Take a moment to read the instructions that come with your plug. Quality plugs when new will have a tip sheet provided with them. In this pay attention to it's wiring diagram for pinology, and notes on how far back to strip the outer jacket, notes on how much insulation to remove from the conductors and all other tips. Many times the instructions will send you to a stripping gauge molded inside the plug for matching up the stripped wire to it's proper length both for how much jacket to remove and how much insulation to strip off the wire. There many times will also be notes on how tight in inch pounds to apply in force to the terminal. It might not be a bad idea to use a torqueingscrew driver for a while in learning how tight this is.
Pay attention to notes on what type of strain relief setting to use depending upon the wire gauge and type of cable you are using. Following this will ensure you do not over-clamp your wire or leave it too loose. This is very important, if too loose, since cable jackets will stretch or shrink more than the copper conductors, the jacket will stretch out of the plug and provide an un-safe bare wire attachment inside the strain relief or plug. If too tight, the strain relief will cut into the cable jacket or expose inner insulated but not jacketed conductors with a force from the clamp that is to a sharp on it's edge or clamping style to do the jacket or wires any good. In the worst instances, tightening the strain relief, or using the wrong or too close fitting of stain relief inserts can compress the cable to the point that most of the rubber is forced out of the joint leaving only a very small amount of insulation between current carrying conductors at a place they are most likely to be flexing and moving about.Since the strain relief on a cord is a sharp angle plate clamping down on the wire, for cords having a more fragile jacket, or cords which won't bend well around a sharp angle such as from plug to the cable bent 90 degrees to it, use of another material coating the cable jacket might be needed to reduce wear on the cable jacket and ease it's flexing at this point. Also on some types of strain relief, use of the strain relief insert, when clamped down will drastically flatten out the cable causing damage to the insulation. Other types of strain relief have almost knife blades clamping down into the cable jacket that tend to cut into it while preventing it from coming loose. Leviton ML-3 plugs are especially bad at clamping into the cable. It would be modifying the plug, but removal of the knife edge completely with a wire wheel grinder is warranted for use with most cable sizes such as 16/3 SJO. A material between the jacket and strain relief, especially on lighter cords is advisable to be used which will also bring the outer diameter of the wire up to a more reasonably clamped size in addition to reducing flex at this point. Leviton http://www.leviton.com/ commercial grade plugs in general tend to flatten out your cable which is bad for anything between small and large cable sizes, but Hubble http://www.hubbell.com/ commercial grade plugs are not made for 12 AWG wire, their insulation does not fit into the plastic terminal shields protecting the area adjacent to where the insulation is taken off, and the strain reliefs are not large enough to clamp or fit 12ga cable of any type well. Pass Seymore possibly makes the best commercial grade plugs because the strain relief is contained within it's body, but Metibo and Bryant would be other sources. Avoid plugs that use screws on the front face of the plug to adjust the tension on the strain relief. This style of strain relief has been known to cut into the jacket of the cable when over tensioned inside of a housing that does not allow a visible inspection of the strain relief. This is especially the case with thermal plastic wire in addition to it possibly slipping out of the strain relief if not tensioned enough. Strain reliefs of this type with only two screws in the face and two clamps on the cable while they do not dig as far into the cable also do not clamp the cable sufficiently to hold it.
Materials for use in a strain relief to expand the OD of the cable jacket: Friction tape, the old Union Stage plug stand by for increasing cable diameter, works well in all around applications no matter what plug is used. It's long lasting and an industry standard. Do not use it on strain reliefs coming out of a fixture however because it is flammable. Gaffers tape and electrical tape are also not optimum for this use. Gaffers tape is not designed to be on a electrical connection and also burns in the case of putting it near a fixture. Electrical tape has problems with being permanent and not just gumming up, but coming off. Plus it's too thin for proper use anyway. Depending upon the size of the wire such as on 16/16 SO wire, you can cut up a garden hose, install it on a cable and have it reduce the amount of flex at the strain relief. Garden hose while not UL listed for this purpose is very abrasion resistant. Other better products along this line of inserting a tubing over the jacket would work on other cable types. Tubing is available in various colors, amounts of flexibility and many different inner and outer diameters closely relating to the size of thinner jacketed cable, or fiberglass covered conductors. A good place for it's use would be on moving light thermoplastic cables which is not exactly the most flexible cable in the world once it gets old. Insert a vinyl tube the wire and as needed use WD-40 or denatured alcohol to get it to fit when tight, it will increase the diameter of the cable to one that's better suited to a standard plug's strain relief such as ½" OD. It will also prevent the strain relief from clamping down too tightly on the jacket that cuts into it instead of the cable's jacket giving way under pressure and pinching the cable. Tubing disperses the pressure put on it much similar to how a ferrule works by dispersing the pressure onto it evenly on all the wire and preventing any of it from spreading out too far it's not clamped. For high temperature strain relief applications, use of high temperature fiberglass electrical tape works well to protect the wire – especially fiberglass sleeved individual conductors, as does some higher temperature rated tubing.
Actual installation of the plug on the wire:
Do not use a knife of any sort to strip wire unless you are working with large solid or single conductor wire. It is much too hard to control the depth of cut with a knife, and is dangerous to the tech person to be using. All it takes is for the technician to nick the insulation of a conductor even slightly, and once that cable is stretched, the insulation will continue pulling apart at the cut exposing the inner conductors. Exposed live conductors in the area of that accidental nick in the wire make it possible for the wires to short or come into contact with the strain relief. This is old' man, electrician's style of stripping wire and many people live by it without a need to. Young tech people should not. There are many commercial cable jacket strippers on the market in addition to a much more safe and simple way of stripping the jacket off your wire with a pair of dikes.
The best way of stripping the jacket off your cable is with dikes. You need a sharp, and quality pair of diagonal side cutting pliers. You get what you pay for with tools, I highly recommend the D2000-48 line of Dikes from Klien for this purpose, or it's Journeymen line for an improved handle. The standard Ace Hardware black handled 6" dikes will also work well as long as they are sharp, but unlike the Klien tool, they will get dull and in need of replacement sooner. Most other brands even Channel Loc won't preform well for this purpose. Do not use micro dikes for stripping cable, it's jaws are not large enough to do real work and it's blade is often sharp enough it will cut thru the jacket before it is removed from the inner conductors. You can sharpen dull or kinked dikes if you can re-align the stop block on them, but they become limited in usefulness and life afterwards. Once the dikes are dull, they won't strip the wire as easily. If they did not cut effectively to start with they will rip rather than cut.
Rubber wire stretches and moves, why not take advantage of this when cutting the wire by pulling the cutting edges away from the inner conductors. Stretch and pull, than cut is the technique. Grab a 3/8 to 1/4" section of the wire with the dikes, pull it back rotating on one jaw to remove the outer jacket away from the inner conductors, and cut. Repeat this technique 4 to 6 times around the circumference of a standard cable. Than give the section to be removed a pull, and in most cases, it will come right off. If it is still attached to the main jacket, than simply flex the cable at that area so the outer jacket stretches and breaks what's left of the bridge on it's own, or simply placing the edge of the dikes against the stretched rubber in most cases will cut it without harming inner conductors. If there is a large non-stretching section of insulation left, grab the strands of rubber with the dikes and lift and cut them as needed. With practice in pulling, twisting than cutting, there is little to no chance of harming the inner conductors and it goes really fast. Also since you already have the dikes in your hand, you are already set up for cutting the jute or fiber filler inside the wire. You can tell dull or bad dikes because especially with fiberglass and soft plastic fillers, they won't cut well. You can also tell because the entire operation will be much more difficult with dull dikes.PVC and many thermoplastic outer jackets won't stretch allowing you to cut just the jacket. You can however much more safely control how deep a cut you are making in it with dikes than with a knife. All it takes is for you to score the jacket some with the dikes. Lightly pinch and cut around the surface, than bend the wire and it in almost all instances come apart at your seam. If not, try cutting/pinching a bit deeper into the wire.Examine your stripped outer jacket no matter how you remove it. Flex the wire at the seam to look at the area hidden by the jacket to ensure you did not nick inner conductors. If you have done so, cut the wire and try again. For most cable you want to strip off 3/4 to 1.1/2" to properly fit it into a plug. If you need to strip more than that, or make a line splice, and the jacket is not coming off with a tug, if at the end, try a smaller stripped section or two for removal. Otherwise, cut into the jacket parallel to the wire, grab the jacket with pliers and pull. The jacket should rip along your cut area. Otherwise, if not use of the above Special Products cable slitter properly allows you to remove the jacket without also cutting into the inner wires. It's a cut/rolling technique. The blade hooks up and rides along the surface of the inner conductors on a rounded edge without cutting into them. This takes practice but is much safer than use of any knife. Mechanical cable jacket removing, and automatic cable stripping tools work or don't work depending upon their settings and what type of cable you are slitting. Often they will just rip away at the insulation or slide along it's surface. For the most part, unless always working with the same cable in a factory setting such tools are not worth the money. Again look at the instructions for your plug. It's going to tell you how far back to slit the jacket. If you cut too little, your conductors won't fit completely into their clamps. If you slit too much, there is a very good chance that it will be so long you are clamping the strain relief directly down onto the conductors, or when tugged they will pull out of the working space of a plug and into the strain relief. Here are some general guidelines: For SJ cable, strip 3/4" to 7/8", for SO cable, strip 7/8" to 1" on Edison type plugs. More than that and there is not enough room in the plug to put the wire and have the strain relief installed properly. This is especially the case with standard Eagle brand metal shelled plugs where the strain relief is really close to the terminals. On Stage pin connectors, it depends upon the brand as to how much room there is in the plug. On Union connectors, there is no extra room, you need to strip the wire at 3/4", cut the white to ½", and the ground to 1/4". On Bates plugs, you should cut it at 1.1/2", cut back the neutral 1/4", and the ground by ½". This will allow for the wires to bend around fixed things such as the plastic of the plug mounting hole, but still allow enough slack in the wire to fit without bunching up inside the plug. In the case of the ground wire, cutting it shorter will take away much of the un-used wire from bending and bunching up.
There are many types of wire strippers on the market, the best kinds are not found on most multi-tool stripper/crimpers unless they are similar to the Klien #1010 series where the stripping jaws surround the wire completely and don't just form a semi-circle at best around the wire that will not in many cases fully cut the insulation. On multi-tools with the strippers located behind the pivot, this requires a long thin handle that is easy to come out of alignment with it's matching jaw. This will not cut the insulation very well or neatly. These the better strippers also have the stripping tool in front of the pivot point for easier use and a less amount you need to open the tool to get the wire in. With use of a pinkie inside the handle, you can operate such strippers easily with one hand. Many companies such as GB make a similar tool to this Klien multi-purpose wire stripper. Better still would be getting a spring activated stripping tool that only strips wire and does nothing else as a primary goal. This spring activated stripper is not a automatic stripper, but the return spring makes it easier to cut down on the insulation than slightly loosen up on the cut so you can slide the insulation off without scraping the inner wires by having the stripper blade touching and abrading the wires as it slides along it's length. Even Radio Shack makes a decent spring activated stripping tool that is superior to a multi tool with it's cutting/stripping edge on the same side of the pivot as the handle. Another benefit of not having the stripper near the handle comes in especially when using the bolt/screw cutter. Frequently the palm of the hand will suddenly get cut in the cutter/stripper area when cutting large screws. These cuts can be very deep and large, thus such tools should be avoided. The only good use of a multi-purpose stripping tool is in the screw cutting holes not available with other tools. To use them however, your tool needs to have a tight fitting between the two cutting surfaces or your screw will not be cut well. The most comfortable wire strippers on the market are the Klien insulated #11045-INS wire strippers. Second to this, a standard pair of Klien #11045 wire strippers are inexpensive and work well. There are similar strippers to this style available from other companies. In tool design, there is a lot of copying of successful designs if not having one company make another brand of tools only with a different product branding on it and sometimes lesser materials making up the cheaper tool.
Pre-shape your wire as it's going to fit into the plug before you strip your wire. Fold out the wires going into an Edison plug into a tri-pod shape with the wire taking a 90 degree angle out and away from the cable after it leaves the jacket, than 1/4" out from there bend it again parallel with the cord where it's going to go into the terminal. This will allow you once the wire is stripped to in most instances insert all three conductors directlyinto the plug at once. Twisting individual conductors might be needed to make them fit nicely into the terminal. Follow the strip gauge or instructions as to how much copper to expose. If you strip too much, the insulation is not serving it's purpose. If not enough, when the wire is shoved into the clamp, the clamp will clamp down on the insulation instead of the copper which will make for a high resistance connection. Most plugs need 3/8" to ½" of material stripped back and there is a large difference between the two strip sizes.
For Bates type Slip plugs, fold the wire out into the form of a fork with the differing length tips at the same height. Strip back 1/4" of material and install a ferrule on the wire. Push that ferrule into the insulation by about 1/16" and use the flat part of your strippers or needle nosed pliers to indent and hold the ferrule in place. You can only do this with rubber insulation over the wire, strip the other types to 5/16". Cut the extra amount of wire extending outside the ferrule. Since you have bent the conductors into a fork, the conductors will be differing lengths anyway, stripping it slightly longer allows the wire in the ferrule to be evenly dispersed and fill up the entire ferrule rather than the wires tapering to a point and possibly not having all the wires clamped by the screw terminal.
Use of a ferrule with bates stage/slip plugs is mandatory because of the amount of area for the wires to fit within the terminal verses the small area of the #8-32 screw clamping down on it. A ferrule keeps the wire together and prevents some strands from getting a lot of compression and some without any. This high/low resistance termination on a wire can cause sparking and shorting between individual strands as the current travels along the skin of the wire than has to branch off into many different strands with differing amounts of resistance to the pin. The screw is also more likely to cut thru a ferrule if there is little behind the wall to support it so you want the wire to fill up the ferrule. Think about a closed can of Coke and how much more stable and crush resistance it is than an open or empty can when held or compressed. If the screw cuts thru the ferrule as it frequently will with small wires in too large a ferrule, you now have a sharp edge cutting into the wire at the terminal.
Should it be necessary to force more than one wire into a terminal, use of a insulated double wire ferrule such as those listed in Allied Electric's catalog is necessary to ensure proper attachment. http://www.alliedelec.com/ This say double wire #12 ferrule will need to be shortened slightly, but will enclose both wires into the space of about a #10 ferrule providing proper clamping on each. It is tricky but will work on stranded wire. It's easier to use with cable stranding than with MTW or THHN stranded wire with less and larger strands, but should work with either sufficiently inside a Bates Plug.
In the case of using smaller conductors in a standard #12ga ferrule, there are other sizes of ferrule on the market that can be used. Otherwise, every time you double up a wire upon itself, it equals 3 wire sizes larger. If I wanted to install a #16AWG wire into a #12 ferrule, I would fold it in half and it's outer dia. is not 13AWG. A much closer fit than that of a 16ga wire just put in the ferrule. This is important because especially on smaller wires, they are easily cut by applying too much tension on them by the screw and inside a large ferrule they will fan out allowing the above shorting and over-clamping of the wire in areas where it's bunched up while little to no clamping on other areas. Double your strip length of the conductors and add 1/4" to the overall length of jacket removed. In the instance of folding over the wire especially in this 16ga size with tinned heat wire, it will be difficult to make the fold in the wire tight enough it will fit inside the ferrule. In this case, it might be necessary to divide your wire in half and cut 1/4" off the top on ½ the strands. This than will allow for a tighter fold especially when closed tighter with pliers, and does not effect the current carrying resistance of the wire because it is only acting as a filler inside the ferrule. Another method for clamping a larger ferrule down on it's conductors is to use a jawed crimp tool – see below, to insert a fold into the ferrule. Than use a pair of pliers to crush that fold down compressing the ferrule onto the wire in a solid plate that will go into the screw. This will ensure the best and most dispersed pressure on all conductors inside an overly large ferrule.
Never use a power tool to tighten the brass screws on a plug. If the tool does not have a clutch setting and is sufficient in power to drive a 3" drywall screw, it is also sufficient to break the screw off preventing the screw from being removed or tightened further. Also over-torqueing the screw does not make for a better connection. Instead it causes resistance in the wire and can make it fail. If your tool does have a clutch, it is safe to use with the proper setting only as long as you finish tightening and checking the screw by hand. This means if your cordless screw driver has a blade lock feature, give the screw a turn to check the torque which should be 1/4 turn past finger tight. Otherwise, you need to get a screw driver out and check torque. This is necessary because depending upon what angle the tip of the driver is put at, it will cause differing amounts of force to be applied to the screw and can set off a clutch setting before the screw is actually at that intended torque. Depending upon the amount of the charge left in the drivers battery, the clutch setting can also be set off without providing sufficient torque on the screw. Also if the screw has a ding in it, your drill could stop driving it before the connection is tight. Your hand can tell the difference between friction, but your drill cannot. Use of power tools without verifying the torque is the most common reason for failure in a plug in addition to over tightening or under tightening it by hand.
The proper tip by the way is a #2 Philips tip screw driver on a Philips screw. Use of a #1 tip on a brass screw will not only strip it but be harder to tighten the screw with it. A 1/4" blade or #8-10 flat head tip on a slotted screw is also the proper size. Use of a 3/16" to 1/8" bladed screw driver will destroy the tool and possibly strip the screw. Match the blade of the screw driver to the size of the head on the screw. Power tools especially cordless screwdrivers can speed up assembly of plugs exponentially, but when using them you must verify they are doing the job intended. For cordless tools I recommend either a Milwaukee or Panasonic 3.6v folding handle cordless screw driver Panasonic #EY-6225 this company makes the Milwaukee tool. It is also very light weight and has removable batteries so you don't run out of charge. DeWalt also makes a small cordless screw driver/drill cross over that might be of use if a bit heavy to use all day long on plugs. These three tools are not cheap but good in power and features over most other cordless screw driver brands. For regular screw drivers, much less power tools in weight and comfort, consider when you buy them holding it all day long. As with all tools, do you want a hard plastic handle or one with sharp angles to it, or one that's comfortable to the grip and large enough to fit in your hand? I recommend either the new Ergonamic Klien "Grip it" line of screw drivers, or at least tools similar to the Klien #603-4B screw driver with comfort grips. http://www.kleintools.com/index.html This style of handle is the standard for the industry and available from any number of vendors from Ace hardware to Ideal. Ideal offers an innovative screw driver with a recess in the tip of it's handle that allows you to tighten wire nuts with it. You can use such a comfort grip or ergonomic screw driver all day long as opposed to a Stanley black and yellow handled screw driver that's going to bite into your hand and cause blisters in a few hours when using it in a normal way or on tight screws.
You get what you pay for. Just about all tool companies have full warrantees on their tools such as Craftsman, Klien, Ideal, Stakon, Ace, Huskey, S&K amongst many others not including Tool Shop or Stanley. This makes some tools worth a few extra dollars in addition to comfort in using them and quality in construction. With the better brands such as Ideal or Klien, your tool will be made out of better materials and not need replacement as frequently. An Ace Hardware screw driver might look almost exactly the same as a Klien one, but the Klien tool will last years longer and thus continue being able to take abuse due to harder steel used in it's tip. Should you break a Klien tool, much less any tool that has a warranty, all you need to do is take it back to a vendor that sells that tool for replacement. Sears is not the only company that replaces their tools. If a company sells a quality or at least decent tool, they usually take it back. Look at the warranty before you buy the tool and inquire about the return policy. In the case of Klien tools, if you buy a screw driver at Home Depot, you can take it back to Ace or even Sears for replacement without a problem even if you don't have a receipt. That's more flexible than buying a chain store's line of tools because there are many more places offering the standard tools. Plus it's better quality in general and fact. Note: the individual sales person might not be familiar with his company's return policy, so calling the manager or taking your business elsewhere might be needed. In the case of my 3/8" blade flat head square shank screw driver, I had someone take it back to Sears. Sears only offers the Cabinet tip version but still exchanged it. This is one of the main differences in screw driver types. Square shank screw drivers allow you to use a Crescent wrench on it to un-stuck tight bolts but won't fit into as tight of spaces. After that, it's primarily a personal choice. Some screw drivers have a metal peg sticking out of the handle. This is for bending solid wire to fit in a receptacle's terminal. Nice but not necessary for use in a theater tech person's tool.
Unless you are up on a ladder 20' in the air and need to make a quick modification to a plug, the use of Leathermen multi tool type knives with their fancy Philips screw driver and other tools is a waste of time. The metal on a knife is going to be much more brittle than on a screw driver and often will sheer or break when over twisted. This could cause you to fall off a ladder and get seriously hurt – think about that when loosening a frozen screw. Warrantees on knives don't work like normal tools, you need to pay to send it back to the manufacturer. Use the proper tool for the job. You do not look cool sitting back stage with a Leathermen multi-tool assembling cable, you look like a lazy idiot. Such tools are not ergonomically designed to be easy or comfortable to use, and since your pressure is off center, it's not very efficient to use them even with a screwdriver adaptor/fitting for the end of the tool that otherwise just makes a hole in your pocket when not in use. Why bother, get the right tools that are much better designed for driving screws. Even a 10 in 1 screw driver while limited in places the overly large shank can get in will preform much better than a glorified Swiss Army Knife. You can also buy at least 5 of these screw drivers for the price of a multi-tool. Multi-tools have their uses, but not for servicing equipment as a primary tool.
Finally, when installing the barrel/strain relief/rear section of the plug on the wire for a normal "Edison" plug, consider installing the strain relief on first, than tightening the face into the plug. Check to verify that the green ground wire is where it is supposed to be especially, as with the other wires black to gold and white to silver, but especially the ground is where it should be. On Euro wire, blue is neutral/silver terminal and brown is hot. You will note that if one side of the cable has the conductors in a clockwise direction having the conductors going Green, Black, White, the opposite side of the cord will have it going Green, White, Black. In installing plugs on a cable, you want to put the proper alignment of the wire on the proper plug because there usually is not room to be crossing wires over to make it work. Should you need to do this however, cross the ground between the other two wires. This way should something go wrong, it's a short to ground and not a arcing inside the plug.
If you move the barrel/strain relief area towards the face part of the plug and set it into it's alignment slot, than keep the back half back from the front by 1/8", this will allow you to suck up a little more wire into the plug without the conductors compromised by the strain relief when tightening it first. Clamp down the strain relief first once the rear half of the connector is aligned into it's slot. This will allow you to clamp the wire jacket 1/16" to 1/8" in from it's end allowing you to hold the cable without it biting into conductors. Not much you can do about wire that's stripped just a bit too long or too close to the strain relief if you install the face on first. Look at the wire being clamped before it's tightened, you don't want to tighten down on the un-jacketed conductors. You want at least 1/16" of jacket on the inside of the connector past the strain relief. Once the cable is clamped, you can screw in the face of the plug and pick up a bit of slack above what would normally be available.
In tightening a strain relief, you do and should not always tighten it down all the way. It all depends upon thickness and area available inside the strain relief. Tightening down a Commercial grade Hubble plug onto a 12/3 SOOW wire will absolutely sever something important inside it. Clamping down all the way when a insert is used on a Leviton commercial grade plug on 12/3 SJOOW wire, will cut into the jacket. This is a problem because the natural tendency is to tighten down the strain relief all the way or fix it when seen not to be tight. In this case, it is by far better to remove the insert on the Leviton plug and leave the cable slightly loose in it's strain relief with this specific grade of wire than clamping down fully on the wire by mistake. The plug, like many is not designed well for 12/3 SJ wire, thus the possible use for tubing or friction tape to bring it up to at least the outer diameter of a 14/3 SO cable which will fit nicely into the strain relief without it's insert.
In the case of Union Stage/Slip connectors, you need to use friction tape to make the limited strain relief function properly. Just about all cable when new especially grade SOOW will shrink and at least once, enough that it's jacket will shrink out of the plug and need repair if there is insufficient pressure on the cord. Friction tape even on SOOW will help prevent this to some degree. The proper tension is key for use with this line of lugs.
Tension and friction is the key to this style of plug. Much of that tension is picked up in the crimped terminals used with it. You should never wrap a bare stranded wire around a screw. If you must use wire directly to the terminal, it should be tinned to prevent it from coming apart over time and making a loose connection. There are special wire washers that are hard to find, but can be used that will act as a ferrule, otherwise the tinning will prevent loose strands from falling outside the screw head and arcing. Always twist the wire in the same direction as it's tightened in the screw. Never divide the wire in half, insert a screw in the gap, than twist the wire to keep it tight. In tightening the screw onto the pin, you are either clamping down on the larger twisted part only and causing it to fall apart or tightening down on the side that wraps the clockwise sucked into the screw in tightening screw causing the other half of your divided wire to be pushed away from the screw and becoming a high resistance and not well tensioned connection to the wire. This will can also cause a bunching up of wire or kink that can short between conductors.. Tinning the wire is also problematic because often the amperage of a short circuit is high enough to re-liquefy the solder and cause the clamping pressure on the wire to be much less. This causes even higher resistance and a possible fire or melting away at this point.
Proper crimp terminals flag and ring terminals are readily available from plug manufacturers, electronic suppliers even McMaster Carr http://www.mcmaster.com/ cheaply and in bulk. If you can not afford a few bucks for the proper crimp terminals, you should not be using this style of plug. The crimp terminal on this brand of plug picks up some tension from pulling on the cord. If it is not crimped properly, it will allow the wire to pull out of the terminal and provide a unsafe connection. In my high school the instructor demonstrated proper tension by screwing a crimped wire to the wall and hanging on it. This is the proper tension because three 12awg wires when crimped properly will support your weight as long as not on a shock loading. Pulling on crimped terminals after crimping them will at least tell you what's a good crimp. Compress the crimpers all the way, they are pre-set to not over tighten your crimp for the wire inside of it. If you cannot tighten the crimp all the way, you should not be crimping things. In fairness, your crimp tool is crucial in providing a good crimp. If it's crimp jaw is not opposite the pivot point from your hand, your leverage is limited. If your crimp tool is not using a real tooth on a rounded anvil section to crimp your terminal even if insulted, as opposed to two semi-circles or a lame mound of a jaw into the terminal, you won't be able to apply enough pressure on the crimp to make it hold without seriously deforming the crimp terminal. In general, insert crimp terminals with the seam of the crimp on the rounded anvil part of the tool and not the jaw into the seam. Look at that even on butt splices. On flag terminals such as used for the hot and neutral wires, on a Union Plug, use the rounded part of the tool towards the seam. You want to find a crimp tool that will crimp the ferrule part of the terminal without cutting into the flag part of the terminal or being prevented from crimping all the way down. There is only one tool that when store bought will properly crimp a flag terminal, that's a Vatco/Klien #1900 multi purpose crimp tool. It's crimp jaws are at the front of the tool and close to the edge so they won't damage the flag terminal. It's jaws while slight in thickness of the metal making up the crimp are also real jaws as opposed to just mounds. Application of two crimps on a flag terminal with this type of tool is needed, otherwise the best tools are available from Klien such as in models #1005 and #1006 with the exact same tool available from Stakon, Ideal, http://www.idealindustries.com/ and many other brands like Thomas Betts.
http://www.tnb.com/ All you have to do is cut and grind off the cutting tool part of the crimper at it's tip. Once the tool is only a crimper and not also a cutter, it is the optimum crimp tool for flag or other terminals. In the case of the Vatco tool, grinding off the stripper/cutter part of the handle is a good idea out of safety. This Vatco tool like with most multi-purpose tools has problems with it's pivot point loosening up. On the above #1010 multi-purpose tool, you can re-tighten a bolt, but the crimping die is useless. On other multi-purpose tools including the Vatco one that use a rivet for the pivot, once the tool loosens up, it won't strip wire, cut screws or crimp things well. That is short of smashing the rivet with a hammer and anvil for a temporary fix of the problem. Since neither tool preforms all of it's design features well you are probably better off getting better quality tools that only try to preform one function.
Since sources such as McMaster Carr sell all forms of un-insulated flag type #8 stud ring terminals, there is not much reason to be using other than the proper sized ring terminal for the wire attached to it. Flag terminals are available in sizes from 22AWG to 10AWG. Otherwise, folding the wire to fit inside the #12 terminal as above with ferrules can be a key factor in getting a proper holding crimp on the wire. In the case of a Union Plug, the center grounding ring terminal carries more of the load applied to a cable, probably than the strain relief and other wires combined will have on them in tension. You need to use the proper un-insulated terminal for the ground, and it must be installed as close to where the outer jacket of the cable ends as possible to ensure the strain relief works properly and is clamping down on outer jacket and not conductors. Do not use insulated ring terminals, even if you pull off the insulation. They are longer in length than non-insulated terminals and will thus force there to be un-jacketed wires inside the strain relief. Because this wire can break and otherwise not effect how a light will work with it, testing slip cable with Union brand plugs a few times a year at least should be required. Union plugs also frequently come with external tooth lock washers to prevent the screw from coming loose. Since you can not use thread locker on the terminals of a plug, the use of this lock washer is the next best thing to do. It will also prevent to some degree the amount of twisting crimped terminals will want to do when tightened under a screw. This lock washer makes this type of plug much more likely not to come loose over time.