A screw terminal connects conductors using multi-twist fasteners and is used in electrical equipment. It requires crimp-type lugs for bare wire and can be mounted on equipment frames or circuit boards. It provides flexibility and accessibility in modular wiring design, and lock washers are needed for mobile transport. A wire nut is a replacement for the screw terminal.
A screw terminal is a device capable of connecting two or more conductors using multi-twist fasteners. Conductors to be connected via the screw terminal are typically fitted with terminal crimp-type lugs that secure the bare ends of the conductor. The screw terminal can be found where there is electrical service and within domestic, commercial and industrial electrical equipment.
Electrical connectors include various types of plugs and sockets that allow anyone to plug or unplug appliances. The screw terminal is a connector that can be mounted directly on the equipment frame, brackets or circuit boards and is used for special purposes such as internal wiring and maintenance procedures. Screw terminals require the bare wire to be twisted, tinned, or installed with crimp lugs or solder lugs, and as a best practice the copper surface of the bare wire should be coated with a layer of tin-lead alloy for protection from oxidation. The crimp lug terminates the wire with a rigid metal eyelet that can be mounted on a terminal block. Without the lug, the mechanical strength and connect/disconnect duration of the bare wire is not sufficient.
The barrier strip and terminal block are each a set of screw terminals that come in pairs. The terminal block, which may be of the solder or screw type, does not provide a barrier between the terminals. The barrier strip usually has insulating barriers between the terminals to prevent accidental shorts.
In modular wiring design, the screw terminal provides the flexibility and accessibility needed to avoid having to disconnect and reconnect parts of the circuit. For example, several test points are required when testing a motor controlled by a relay controlled by a start/stop switch. Test points are readily available for voltage testing from a digital voltmeter, and the faulty one can easily be isolated.
The screw terminal can also be used in mobile transport. This application requires lock washers which ensure that the screw does not loosen due to vibration. The luster terminal is also suitable for both fixed and mobile installations due to its compactness and covered conductive portions. Set screws are used in the polished terminal where the screw presses into the bare or tinned wire.
A replacement for the screw terminal is the wire nut, which is a piece of insulator with a conductive clamp inside. It is used as a cap for wires that have been twisted together side by side. The exposed conductor is inserted into the wire nut, which is turned clockwise to secure the wire until there is no exposed conductor. Temporarily removing the wire nut allows for maintenance measurements and troubleshooting.
Protect your devices with Threat Protection by NordVPN
