The source neutral wire on the receptacle is removed and spliced to the white running to the switch, and to a pigtail back to the receptacle neutral. At the switch, the neutral wire is needed to power some dimmer switches and is now required in most switch boxes.
A doorbell circuit for two or more doors will have a separate contact on the chimes for each button included. At the chimes, one wire from each button is spliced to the output wire on the transformer. The second wire is connected to one of the contact screws on the chimes.
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.
This drawing shows the wiring for adding a new light fixture using an always-hot receptacle outlet as the source. New cable is run from the receptacle to the new fixture location and a switch loop cable is run from there to the new switch location.
This is a wiring diagram for an antique floor lamp with 4 bulbs, one main bulb and 3 peripheral, and usually smaller bulbs. The main bulb threads into a standard socket with an integrated switch and the three peripheral bulbs are wired to a single switch. The secondary switch may have wires colored black, blue and red or, if it’s an old switch, other colors or texturing may be used to distinguish them.
This diagram shows the wiring for a switch to control multiple receptacles. The source for the circuit is at the switch and the receptacles are wired using pigtail splices to make the connections.
Here 3-wire cable serves a split receptacle. The bottom half of the receptacle is controlled by a switch and the top half is always-hot.
A hardwired doorbell includes a small transformer that converts the household alternating current (AC), to direct current (DC) for the doorbell chimes. A small, 16 awg wire runs from the door button to the chimes. When pressed, the button will send the transformer output through the chimes, sounding the bell until it is released.