Lamp cords are usually one color, making the standard black-hot, white-neutral guidelines useless for determining polarity. Other methods are therefore used to determine the polarity on a lamp cord. Check the insulation on the cord wires closely and you will find either a textured bead or a thin colored line running along one wire, this is the neutral.
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.
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 page contains wiring diagrams for adding a new light fixture using an existing receptacle as the source. Diagrams include adding a light from a switched receptacle and tapping an always-hot outlet. Different wiring arrangements are included to allow for either the light or the switch to come first in the circuit.
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.
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.
This type of switch will be referred to as a 2 circuit lamp switch when shopping at home stores. Don’t mistake this for a three way switch (pictured below), the two do not function in the same way.
If, however, you’re putting in a new hardwired doorbell or you need to repair an existing one, the diagrams on this page illustrate the most common installations you will find. Included are wiring for a typical hardwired doorbell, a two-button doorbell, an old house doorbell powered by a battery, and an alternate power source using an ac adapter.