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Electricity
Electricity is the flow of electrons through a conductor- copper or aluminum wires in household construction. Electricity
must travel in a loop called a circuit. In most cases, power travels out to a fixture or device through a hot wire – usually
coated with black or red insulation – and back through a neutral wire, white insulation. Newer homes are grounded.
Grounding connects all outlets to the earth and is an essential safety feature. Ground wires are either bare copper or
have a green insulation. Most household fixtures use 120 volts (may be labeled as 110). Large items may require
220/240 volts. Electrical power comes into the neighborhood through overhead (or underground) high voltage wires.
Transformers reduce the amount of voltage to a relatively safe load of 120 volts. Through a service head, these wires
enter a meter, which records how much power a home uses for billing purposes. From the meter, the wires go into a
service panel, which divides the power into branch circuits. Most homes have three wires entering the service panel (2
hot (120 volt wires) and a neutral wire). Underground wires run through a conduit – a pipe that protects the wire.
Service panels have breakers in them which divide the power into circuits. Each circuit carries power from the service
panel via hot – black or red- to various outlets and then back to the sercive panel via a neutral – usually white- wire.
Wiring a switch to a light with the power starting at the switch:
Yellow wire is ground wire
Yellow and green caps are called wire nuts
There are three yellow wires in the switch box. This is called a pigtail…see Mr. Capps
Wagner, Willis H., and Howard Bud Smith. Modern Carpentry: Essential Skills for the Building Trades. Tinley Park, IL:
Goodheart-Willcox, 2008. Print.