Pushbutton switches make or break electrical connections as part of a system that controls a process, such as a manufacturing line. Indicator lights with labels or color-coded caps are used to display the current state of a process, such as "completed. " The pushbutton unit is composed of a pushbutton actuator for making or breaking electrical connections, a holder for securing the actuator to a control panel and for housing a light, and one or more contact blocks for connection to electrical wiring. Contacts within a contact block can be normally open (NO) or normally closed (NC), so that pressing the button starts or stops a process. Holders accommodate a range of control panel thicknesses and may include lamps to illuminate the button. Pushbutton actuator head types include mushroom, flat-surface, raised-surface, and key-operated, and may be illuminated, color-coded, and labeled. According to the requirements of an application, actuators may operate only as long as the button is held or they may lock into position when pushed and unlock when pulled or twisted. Pushbuttons and indicator lights are used in applications such as manufacturing process controls and as emergency shutoffs in industrial workplaces.
