Kinds of Wire Splicing & Joints

Wire Nuts

• Most home electrical wiring requires the use of wire nuts for joining two or more wires. Wire nuts can join solid wires to solid wires, stranded wires to solid wires, or stranded wires to other stranded wires.

  Two or more solid wires join together by twisting the wires together, then a wire nut screws onto the bare copper ends. For solid-to-stranded or stranded-to-stranded wire splices, the two ends are held together, and a wire nut is placed over the ends and screwed onto them.

Pigtail

• A pigtail splice uses wire nuts to connect one wire to several shorter wires that supply receptacles or switches in the same box. This splice is very similar to a standard splice, except the wires don't leave the wiring box.

  For example: Two switches in a box each require a hot wire. The electrician pigtails the incoming hot wire to two or more 8-inch long wires. Each wire then connects to a different switch.

Crimping Barrels

• All of the ground wires in a wiring box must connect to the grounding electrode. When a box has more than two or three ground wires in it, using a wire nut to connect them becomes cumbersome and difficult. A different kind of splice is made for these types of ground connections using a crimping barrel. The bare ground wires are twisted together, and a metal barrel is placed over the twisted portion and crimped into place.

Terminal Joints

• The joint where a wire connects to a device such as a switch or receptacle is called a terminal. A wire wraps clockwise around a terminal screw; the screw is then tightened. Another type of terminal places the wire between two plates, and a screw presses the plates together to make contact with the wire end. On a terminal buss, the end of the screw holds the wire against the buss bar. Push-in terminals hold the wire in place with a brass spring clip.