Electricity and Electrical (3-Way & 4-Way Switch Installation)

Standard electrical switches are designed to turn lights or other electrical devices "ON" and "OFF" from one location.   In many instances in a home, having the ability to turn lights or other electrical devices "ON" and "OFF" from more than one location is desirable and provides added safety and security. Stairways are one of the most common areas in a home to utilize switches that provide "ON" and "OFF" capability from more than one location.  A switch is placed at both the top and bottom of the stairwell providing added safety. Rooms that have multiple entry and exit points are another common area for multiple switches as are long hallways; thereby, allowing individuals to turn on lights upon entering the hallway at one end and turning the lights off upon exiting the hallway at the other end.
 
3-Way switches are designed to turn lights or other electrical devices "ON" and "OFF" from two locations and depending on the circuit configuration one or two 3-Way switches may be used in a circuit that turns lights or other electrical devices "ON" and "OFF" from more than two locations.
4-Way switches are designed to turn lights or other electrical devices "ON" and "OFF" from three or more locations.  In theory there is no limit to the amount of switches that can be installed on any one circuit. Providing the wires and connections to make multiple switch circuits work can be confusing as the wire locations are subject to whether the live feed into the circuit is at a light fixture, electrical device or at one of the switch locations and how many devices are actually being controlled in the switching circuit. It should be noted that the circuit can control more than one light fixture. Additional light fixtures are run in parallel to the first fixture.The possible wiring diagrams for the installation of 4-way switches are almost unlimited. It is possible that the light fixture resides in the middle of the wiring with switches before and after the light fixture.  Figures 6 and 7 provide wiring diagrams where the light fixture resides in the middle of the circuit. In theory, there is no limit to the number of switches that you can have in any specific circuit.  Additional switches in the circuit are 4-way switches and are installed between two 3-way switches, as shown in Figure 8. If your application requires multiple light fixtures controlled by the same 3-way switches the additional light fixtures should be wired in parallel to the first fixture.  The circuit should be connected to the point where the first light fixtures wires are connected to the power - after the switches.
 
The preceding home improvement article was contributed by Renovation Headquarters, owned and operated by Bill Prudehome. With more than 25 years in senior positions in the construction industry, Bill has been providing home renovation, home remodel and repair services to individuals and small business throughout North America.