Terminal Blocks

Terminal blocks are insulated, modular blocks that secure two or more wires together. They are the perfect solution for complicated control circuits that require secure, well-organized and semi-permanent wire connections that can easily be switched out for repair or inspection in the field. Within a control board, terminal blocks are snapped firmly into place on a mounting or DIN rail. When modifications to the circuit are performed, they can easily be added or removed from the rail without interfering with other wire connections.

There are three common terminal block types: feed-through, PCB mount and barrier strip. Feed-through terminal blocks contain one input and one output contact where two separate wires are inserted into opposite sides of the housing to connect the two wires together. PCB mount terminal blocks are made for mounting on printed circuit boards (PCBs). Some types clamp bare wires into the housing, which is then soldered to a PCB, while others can be plugged into a pin strip that is mounted to the board. Barrier strip terminal blocks feature a screw down terminal that attaches a bare wire or a ring or spade terminated wire. The wire is placed onto the screw and tightened into the housing for a secure connection. Barrier strips often have more than one termination point for multiple wires and provide small barriers between the individual terminals.

Three common wire-securing methods for terminal blocks are: screw-type, push-fit and insulation displacement connector (IDC). Screw-type terminal blocks utilize a screw that tightens a clamp to secure the wire into place. Push-fit terminal blocks use spring-loaded levers that allow wires to enter the terminal block in one direction, but do not allow them to be pulled back out. Insulation displacement connectors (IDC) allow the unstripped wire to be inserted into the terminal block, which then uses two metal blades to cut through the insulation, making the proper contact with the conductor.