This page contains diagrams to add a new electrical outlet to an existing circuit. Arrangements are included to use an existing receptacle circuit or lights and switch circuits as the source for a new wall outlet.
This diagram illustrates the wiring for a bedside lamp with two sockets. The top socket A, holds a standard incandescent bulb. The second socket B, typically holds a small, low-wattage bulb similar to a night light bulb. The switch allows for energizing the top bulb only, the night light only, both bulbs at once or for turning both bulbs off.
At the switch, the other end of the black wire is connected to the bottom terminal on the switch and the black wire going to the new light is connected to the top terminal. The white wire from the receptacle is spliced to the white wire going to the light, it doesn’t connect to the switch in this diagram, but a new electronic switch will usually include a neutral wire connection. At the light the black wire connects to the hot terminal on the fixture and the white goes to the neutral terminal.
The white wire on the switch loop is used to carry current from the source to the switch and it is marked with black tape or paint to label it as hot. The black on the switch loop runs from the top switch terminal to the top half of the receptacle. With this arrangement the top half of the duplex is controlled with the switch and the bottom half is always hot.