Answer: It is often desirable in designing an electric wiring system to be able to

Chapter 2, Problem 2.33

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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 fourterminal, two-position switch. The switches are shown schematically in Fig. P2.33(a), which illustrates a three-way switch, and P2.33(b), which illustrates a four-way switch. a) Show how two three-way switches can be connected between a and b in the circuit in Fig. P2.33(c) so that the lamp / can be turned ON or OFF from two locations. b) If the lamp (appliance) is to be controlled from more than two locations, four-way switches are 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 Fig. P2.33(c) to control the lamp from three locations. (Hint: The four-way switch is placed between the three-way switches.) Figure P2.33 Position 1 Position 2 (a) 3 4 Position 1 Position 2 (b)