A contact block is an electrical circuit connector that is used to turn on (make) or turn off (break) an electrical circuit. Contact blocks are commonly found connected to switches, relays and circuit breakers, once these devices are active the contact block allows current to flow and complete a circuit.Types of Contact BlockContact blocks are usually designed as an accessory to fit a specific device, therefore matching the correct contact block and device are essential. The contact blocks are available with a wide range of contact configurations that allow the main device to change a circuit in many different ways. Typical contact configurations available are:• 1NO (One normally open contact)• 1NC (One normally closed contact)• 1NO/1NC (One normally open and one normally closed)• 2NO (Two normally open contact)• 2NC (Two normally closed contact)• 2NO/2NC (Two normally open and two normally closed)Light BlocksPush button light blocks are an addon block that mount to the rear of a push button switch alongside the contact blocks to act as an indicator light. The light blocks are turned on when the push button is pressed and illuminate through the button head.Types of Light BlockLight blocks are available in two types:• LED – These light blocks feature a fixed bright LED that is designed to last the lifetime of the push button. LED light blocks are available in a variety of colours to match the button colour.• Incandescent – These light blocks feature a changeable incandescent bulb. The bulbs produce a white light that shines through the button head to produce the required colour.