This diagram illustrates wiring for a circuit breaker with a built-in ground fault circuit interrupter. This 20 amp ground fault interrupter breaker is a form of gfci that can be installed at the circuit source. This kind of circuit is used for dishwashers, whirlpool spas and other locations where water contact is likely.
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 diagram is similar to the one above, but the switch comes before the new light in the circuit. New cable is run from the receptacle to the new switch location and from there to the light location. The switch may also be added in the the same box with the receptacle as in the diagrams at this link, where the two are installed in a double-gang electrical box.
This drawing illustrates the wiring for a split receptacle controlled by a switch. The tab connecting the hot terminals on the receptacle is removed and the source hot is connected to the bottom half. The source neutral is connected to one of the neutral terminals on the receptacle.
This is an updated diagram for the same circuit. Here the source neutral, known as a grounded neutral, is run through to the switch box where it can be used to power switches that require a neutral connection. A neutral connection like this is now required in most new switch boxes as of the code changes in 2011.
Above is a wiring diagram for a standard, 3-way lamp switch. This socket is used with a three way bulb containing 2 separate elements that are energized separately and then together as the switch knob is turned, for varying degrees of light.
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.
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.