Here I’ll show stripping insulation because it is often done at the rough wiring stage. Splicing and joining wires are operations that happen during the finish wiring stage after drywall has been installed. Like PVC pipe, NM cable (also called Romex) is easy to work with,
but you still need to take care when stripping and joining. In particular, be sure not to nick the wire insulation when you strip the sheathing; bare wires could touch each other and cause a short.
This work is often done with a knife, but it pays to buy and use good tools, especially if you are a beginner. A number of good tools are on the market, but a pair of cable and wire strippers like the one shown on this page may be the best option.
It will make quick and easy work of stripping without nicking wires. It has slots for stripping 12/2 and 14/2 cable, as well as holes for stripping 14- or 12-gauge wire. If you need to strip other sizes of cable or wire, go ahead and buy a tool for those sizes.
For clarity, I show these stripping operations being performed prior to running the cable through framing to the box. However, it is often easier to run an unstripped cable to the box location and then do the stripping just prior to inserting into the box.
- Measure to cut off a bit more than 6 in. of sheathing. To do this quickly, note where 6 in. comes on your tool, so you don’t have to repeatedly use a tape measure.
- Slip the cable into the slot for its size (here, 14/2), squeeze the handles together, and give it a twist as you squeeze. Then slide the sheathing off.
- Pull any paper or plastic strips off the wires, and cut them near the cut end of the sheathing. Or, it may be easier to simply tear off the paper. If you will strip the wires as well at this point (you may decide to do this later), measure 3⁄4 in. or so.
- Slip the wire into the correct-size stripper hole, squeeze, twist, and pull the insulation off.
- If you feel skilled and want to try doing it the way many pros do, you can practice until you get good at stripping both cable and wire ends using a pair of lineman’s pliers.
Once you are used to working this way, you can squeeze with just the right pressure so you quickly strip without nicking wires.
Some people splice solid wires together simply by poking them into a wire nut and twisting, but you’ll get a firmer connection by twisting them together first and then adding a wire nut.
- After stripping about 3⁄4 in. of insulation from two or more wires, hold them tightly side by side with their ends aligned.
- Grab the wire ends with the tip of a pair of lineman’s pliers and twist clockwise several times, to get a neat-looking, tight joint.
- Pull on the wires to be sure the connection is tight; you should not be able to easily untwist. Snip the tip of the splice at an angle with the lineman’s pliers or diagonal cutters.
- Insert the wires deep into a wire nut and twist clockwise to tighten.
When joining a fixture’s stranded “lead” wire to one or more solid wires, wrap the lead clockwise around the wire(s) so the lead extends about 1⁄8 in. past the solid wire. Insert the wires deep into a wire nut and twist clockwise until you achieve a firm connection.
Wrapping With Tape
Wrapping the bottom of a wire nut and the wires with professional quality electrical tape is not usually considered necessary, but doing this is a good idea. At the very least, make sure that no bare wire is exposed after the wire nut is attached.
Connecting Wires To Terminals
Many switches and receptacles have side-mounted terminals with screws. (They may have poke-in options as well, but most electricians don’t trust them to make reliable connections.) To connect wires,
- strip off a full 1 in. instead of the 3⁄4 in. used for splicing. Use the tip of a pair of wire strippers (as shown) or longnose pliers to twist the stripped wire into a question-mark shape.
- Loosen the terminal—brass for the hot wire and silver for the neutral—and slip the stripped end under the screw head. Squeeze the wire to tighten it around the terminal.
- Tighten the screw firmly.
- Also, tighten any other terminal screws that are loose. Wrap the device with electrical tape, so all the bare wires and terminals are covered. Some high-quality devices have push-in terminals that get tightened after inserting the wire end. These make for reliable connections.