Four-way switches can be used with how many three-way switches?

A four-way switch is specifically designed to work in conjunction with two three-way switches to control the same light or set of lights from multiple locations. In a typical configuration, you would have one three-way switch at each end of a hallway and a four-way switch in between them. This allows the lights to be turned on or off from either end of the hallway and from the point where the four-way switch is located.

This configuration provides flexibility in lighting control and is commonly used in larger spaces where multiple points of control are beneficial. The presence of two three-way switches means that you can achieve complete control over the circuit, allowing you to turn the lights on and off from different locations seamlessly.

In contrast, options suggesting one three-way switch or any other number do not provide a complete solution for controlling lights from multiple locations in the way that a four-way switch is intended to do. Thus, the correct understanding aligns with the mechanics and functionality of the four-way switch system, confirming that the answer is indeed two three-way switches.