There are four terminals in an intermediate switch. These change the flow of current from one circuit to another circuit. In some cases, there is straight connection between the terminals, and in others, there are crossed-over connections.
An intermediate switch is a switch with four terminals that controls a device from more than two locations. An intermediate switch is similar in structure to a Double Pole Double Throw, and it allows three switches to control one light. For example: a common use for an intermediate switch is in a multi-story building or on a landing where there is one switch is at the bottom of the stairs, one at the top of the stairs, and one at the end of a landing. The middle switch is an intermediate switch.
The use of two two-way switches and one intermediate switch allows control of a light from three different locations. Similarly, the use of two two-way switches and four intermediate switches allows control of a light from six different locations. Intermediate switches have two sets of terminals. The two wires coming from one direction connect to one set of terminals and two other wires connect to the two other terminals and then move forward to the next switch of the series.