It is often desirable in designing an electric wiring system to be able to control a singl...

It is often desirable in designing an electric wiring system to be able to control a single appliance from two or more locations, for example, to control a lighting fixture from both the top and bottom of a stairwell. In home wiring systems, this type of control is implemented with three-way and four-way switches. A three-way switch is a three-terminal, two-position switch, and a four-way switch is a four-terminal, two-position switch.The switches are shown schematically in Figure (a), which illustrates a three-way switch, and Figure (b). which illustrates a four-way switch.

a) Show how two three-way switches can be con nected between a and b in the circuit in Figure (c) so that the lamp I can be turned onor offfrom two locations.

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b) If the lamp (appliance) is to be controlled from more than two locations, four-way switches arc used in conjunction with two three-way switches. One four-way switch is required for each location in excess of two. Show how one four-way switch plus two three-way switches can be connected between a and b in Figure (c) to control the lamp from three locations.

Figure (a)

Figure (b)

Figure (c)