How to permanently repair wire

Heat Shrink and Solder Method
Materials needed:
-Heat shrink of correct gauge to fit over wire.
-1 soldering iron (cordless or plug-in type acceptable.)
-1 length of rosin core solder, (six to eight inches will suffice.)
-1 tube, bin, or bucket of wire or pipe flux.
-1 pair diagonal wire cutters.
-1 razor blade or sharp knife.
-1 moist sponge
-1 small paintbrush
-1 bottle isopropyl alcohol. Rubbing alcohol may be substituted. Grain alcohol may not be used.

How to do:

1. Preparation and location of broken wiring.
   a. Plug in soldering iron. Place in an area that it will not cause either fire or injury during the following work.
   b. Ensure that sufficient slack in the wire exists to remove all damaged portions and still rejoin ends without undue stress. (If a wire is damaged in several places around a break all of the affected areas will need to be removed. In the event that this is what you require, repeat this procedure as necessary or completely replace the wire in question. As a general rule, more than five repairs in a one-foot section will require splicing in a new piece of wire as a replacement for the damaged area.)
   c. Mark approximately ¼ to ½ inch past cut mark.
   d. Using razor blade or sharp knife, lightly score outside coating of wire until a visible groove can be seen all the way around the wire. This can be done either by slowly rocking the blade back and forth in a rotary motion or by rotating the blade around the wire until this is achieved. Be careful not to cut into the conductor or nick any of the strands in the process.
   e. Flex the wire back and forth at a forty-five-degree angle until the center conductor is visible inside the score mark made on the wiring. The outer shielding should separate if cut deep enough. If this does not occur easily, repeat step c. as necessary.
   

2. Repair
   a. Cut sufficient heat shrink, (of appropriate diameter,) to cover both sides of prepared wire. 1.5 to 2 inches should be more than necessary. Slide over one of the two halves of the wire about to be joined. (Note: Ensure heat shrink is on wire and out of the way before soldering. From personal experience I can attest to the feeling of foolishness resulting from looking for a piece of heat shrink that is sitting quite innocently off to the side after soldering two bits of wire together.)
   b. Dip both halves of wire into flux. Care should be taken not to use too much flux or to cover the wire shielding in flux, only the conductor needs a light coat.
   c. Tin soldering iron by taking a small piece of solder and melting it against the end of the iron. This should be done approximately ½ to ¼ inch from the end of the iron. Lightly rotate the end of the iron on the moist sponge two to three times. There should now be an even, almost mirror sheen of solder all the way around the end of the iron. (Note: This may require some practice beforehand.)
   d. Gently mesh the conductor of both halves of the wire. It may be required to loosen the wire slightly by twisting in the opposite direction the wire was spun by the manufacturer. (If you are attempting to solder solid conductor wire simply touch the two halves together and proceed to the next step.) Smooth down the joined halves so that no strands poke out in random directions. Neatness counts.
   e. Take the soldering iron and place it on one side of the wire. Leave there until flux boils away and a small curl of smoke appears. (CAUTION: DO NOT INHALE SMOKE, VAPORS FROM SOLDERING WORK CONTAINS LEAD.)
   f. On the side of the wire opposite the iron place the end of an individual strand of solder. A small amount of solder will melt and then coat the wire.
   g. Immediately remove the iron and the solder. You should now have a shiny, silver in color bond between the two wires. Cold solder joints, (insufficient heat,) can be identified by a gray, waxy color or by spots or inconsistency in the thickness of the solder on the wire. If a cold solder joint is the result you will need to repeat the process until correct. It is more than probable that on your first attempt that this will be the result.
   h. Clean area after allowing it to cool with a small amount of rubbing alcohol and paintbrush. Again, neatness counts here. The object is to remove all of the visible flux from the area of the repair.
   i. Slide heat shrink over repair. Heat shrink should be heated with a commercially available hair drier until both ends of the repaired area are sealed. Test heat shrink before using to make sure that it will shrink to the original diameter of the wire shielding. A good guess as to the correct diameter can be gauged by using material only slightly larger than the wire under repair.
   j. Test repaired wire. (If this involves something carrying household current or significant amounts of electricity, back up three or four feet, wear goggles, do not touch the appliance under test, and have a fire extinguisher ready.)

Environmental Splice Method:
Materials needed:
-1 complete splice set of appropriate gauge. Should include a metal barrel approximately 1 to 1.5 inches in length and a piece of heat shrink (not applicable in some commercial cases.)
-1 pair of crimping pliers.
-1 razor blade or sharp knife.

(Yes, the first section is the close to being the same as the one above. This was done for clarity. I did not want a step reading: 'go to step one and follow that' as step one. See, I told you it was slightly confusing.)

1. Preparation and location of broken wiring.
   a. Ensure that sufficient slack in the wire exists to remove all damaged portions and still rejoin ends without undue stress. (If a wire is damaged in several places around a break all of the affected areas will need to be removed. In the event that this is what you require, repeat this procedure as necessary or completely replace the wire in question. As a general rule, more than five repairs in a one-foot section will require splicing in a new piece of wire as a replacement for the damaged area.)
   b. Mark approximately ¼ to ½ inch past cut mark.
   c. Using razor blade or sharp knife, lightly score outside coating of wire until a visible groove can be seen all the way around the wire. This can be done either by slowly rocking the blade back and forth in a rotary motion or by rotating the blade around the wire until this is achieved. Be careful not to cut into the conductor or nick any of the strands in the process.
   d. Flex the wire back and forth at a forty-five-degree angle until the center conductor is visible inside the score mark made on the wiring. The outer shielding should separate if cut deep enough. If this does not occur easily, repeat step c. as necessary.
   

2. Repair
   a. Insert stripped end of wire into one end of crimp barrel. Proper stripping can be checked by ensuring that the end of the wire is visible in the notch in the center of the barrel and the end of the stripped portion is flush with the end of the barrel. Some trimming may be required to achieve this.
   b. Squeeze end of crimp barrel until torque lockout is engaged on pliers or until metal of barrel surface is thoroughly indented. Do not squeeze so hard as to punch through the crimp barrel or bend it inside the jaws of the pliers. Barrels and pliers are color coded to the appropriate wire gauge, red being smallest, then blue and finally yellow. Crimp barrels are usually color-coded, use the same color notch on the crimping pliers corresponding to the barrel you are using.
   c. Slide heat shrink over other side of wire. (If applicable.)
   d. Repeat steps a. and b. for other half of wire.
   e. Slide heat shrink over repair. Heat shrink should be heated with a commercially available hair drier until both ends of the repaired area are sealed. Test heat shrink before using to make sure that it will shrink to the original diameter of the wire shielding. A good guess as to the correct diameter can be gauged by using material only slightly larger than the wire under repair.
   f. Test repaired wire. (If this involves something carrying household current or significant amounts of electricity, back up three or four feet, wear googles, do not touch the toaster under test, and have a fire department ready.)