Electrical 101

See the following electrical outlet wiring diagrams using NM cable and four outlets. Also included are diagrams of a 240 volt dryer outlet and an outlet grounding diagram.

In the diagram below, a 2-wire NM cable supplies line voltage from the electrical panel to the first outlet box. The black wire (line) and white (neutral) connect to the outlet terminals and another 2 wire NM that travels to the next outlet. This repeats until the end of the chain.

Diagrams shown on this page are simplified for clarity. Electrical outlet boxes can have numerous NM cables going in and out. See Actual Switch Box Wiring Diagram.

Typical NM Ground Wire Connections Diagram is shown below.

Typical Ground Wire Connections for Outlets

All ground wires and device terminals are connected together in each outlet box.

In each electrical box, all ground wires are connected together. Ground is also connected to the ground terminal of a device (switch, outlet, light fixture, etc).

NM Cable Ground Wire Connections Diagram for Outlets

Typical NM Ground Wire Connections Diagram for Receptacles

Dryer Outlet Wiring

Below, a 3-wire 10 AWG NM cable supplies 240 volts from the electrical panel to the dryer outlet box. The black wire (line “A” phase) and the red wire (line “B” phase) supply the 240 volts. The white wire supplies neutral to the dryer outlet.

The ground connection is shown in this diagram.