Follett 01017508

SCREW TERMINAL BLOCK 6 CIRC X

A screw is a type of fastener, in some ways similar to a bolt typically made of metal, and characterized by a helical ridge, known as a male thread (external thread). Screws are used to fasten materials by digging in and wedging into a material when turned, while the thread cuts grooves in the fastened material that may help pull fastened materials together and prevent pull-out.

A screw drive is a system used to turn a screw. At a minimum, it is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. Usually, it also involves a mating tool, such as a screwdriver, that is used to turn it. Other examples include Phillips head screws and screwdrivers, and Allen hex screws and wrenches.

A terminal is an electrical connector acting as the reusable interface to a conductor and creating a point where external circuits can be connected. A terminal may simply be the end of a wire or it may be fitted with a connector or fastener. Most electrical connectors have a plug that connects to a socket. The connection may be removable, require a tool for assembly and removal, or serve as a permanent electrical joint between two points. An terminal adapter can be used to join dissimilar connectors.

A screw terminal is a type of electrical connector where a wire is held by the tightening of a screw.  The wire may be wrapped directly under the head of a screw, may be held by a metal plate forced against the wire by a screw, or may be held by what is, in effect, a set screw in the side of a metal tube. The wire may be directly stripped of insulation and inserted under the head of a screw or into the terminal. Otherwise, it may be either inserted first into a ferrule, which is then inserted into the terminal, or else attached to a connecting lug. which is then fixed under the screw head. The terminals easily can be re-used in the field, allowing for the replacement of wires or equipment, generally with standard hand tools. Screw terminals usually avoid the requirement for a specialized mating connector to be applied to the ends of wires.