Use the techniques described here when joining wires in electrical boxes, receptacles, and switches.

Never attach more than one wire to a terminal. Codes prohibit it, and it's unsafe because terminal screws are made to hold only one wire. An easier way to join many wires to a terminal is to cut a short piece of wire (about 4 inches), strip both ends, and splice it to the other wires as shown to form a pigtail.

As an alternative to using wire nuts, twist wires together so that one extends 1 inch beyond the splice. Solder the twist and loop the extended wire. Tape the soldered splice before screwing the wire to the terminal. If you are planning to take this route, be sure local codes permit soldering.

How you ground receptacles and switches depends on the type of wire you're using as well as the type of box. With flexible armored cable (BX), Greenfield, or rigid conduit, the metal of the wiring casing and the metal of the box substitutes for the grounding wire. Simply by attaching the device firmly to the box, you have grounded it. Some local codes require that you also attach a short grounding wire, as shown. If you're working with nonmetallic sheathed cable (Romex) and metal boxes, connect short grounding wires to the box and to the device. With nonmetallic boxes, the cable's grounding wire connects directly to the device.

Most receptacles and switches have connection holes in the back. To make a connection, strip the wire (a stripping gauge often is provided, showing you how much insulation to remove) and poke it into the correct hole. On a receptacle, the holes are marked for white and black wires. However, most professionals do not use these holes. Wires inserted this way are simply not as secure as those screwed to a terminal.