Additional start and stop push buttons may be needed on a system that is very large. For example, if the system is installed over a large area, such as for a long conveyor system that may be over several hundred feet long, it would be inconvenient and unsafe to have one start and stop button at only one end of the system. To make the system more safe and to make it more convenient to start and stop the system, push-button switches can be installed every 40 feet. Each additional start button should be connected in parallel with the first start button, and all additional stop buttons should be connected in series with the original stop button. Figure 1 shows examples of the additional start and stop push buttons in a three- wire circuit.
Right: Fig. 1 The wiring diagram for a three-wire
control circuit with additional start and stop push buttons added to the
circuit is shown at the top of this figure, and the ladder diagram of just
the control circuit is shown at the bottom.
