Electrical or outlet boxes are made of metal or plastic and used to house wire connections including for devices like switches and receptacles, as well as for junction boxes to protect wire splices. Shapes include, square, round, octagonal and rectangular. Sizes up to 4 inches square are available. Use the largest box possible to provide NEC required space for wires and other conductors.
In this example a new wall receptacle can be installed using an existing receptacle in an adjacent room. This can often be the easiest and most likely solution to access a source for a new receptacle or a switch to a new light fixture. Set the new outlet box in the same wall space as the existing one to simplify running the cable.
If the ends of the wires are too far apart, the nut won’t go on properly. Be sure the ends match up before twisting them together. If necessary, snip off a bit at the tip to get them even before attaching the connector.
Test for continuity, voltage, current and resistance. Both analog and digital meters are available. A digital meter is simple to use, easy to read and inexpensive. Analog meters are not as easy use or read and are becoming obsolete.