Final answer:
The purpose of three-way switches is to allow control of a lighting fixture from two different locations, using a three-wire system for safety against electrical hazards, enhanced by features like the GFCI.
Step-by-step explanation:
The purpose of installing three-way switches is to control the lighting fixture from two locations. This capability is essential for the convenience of being able to switch lights on or off from different positions in a space, such as from either end of a hallway or stairwell. The three-wire system used in this type of switch setup helps to guard against thermal and shock hazards by utilizing a live/hot wire, a neutral wire, and an earth/ground wire, with the neutral and earth/ground wires ensuring safety by being at zero volts relative to the earth.
This setup allows the neutral wire to serve as a return path to complete the electrical circuit while also providing an alternative path through the earth in case of insulation failure. Additionally, the inclusion of a ground fault circuit interrupter (GFCI) or circuit breakers can further prevent electrical shock by interrupting excessive currents.