Terminal blocks are a necessary attribute in the field of electrification. Due to their diversity, it is possible to flexibly configure electrical circuits, closing the windings, due to their uselessness, and disconnecting unnecessary circuits.
Terminal blocks are made of a dielectric housing and several mounting screws. In some cases, small metal lamellas are used (they allow you to conveniently fix the wire in hard-to-reach places).
Terminal blocks are an integral part of the supply during electrical installation and commissioning. On one side of the terminal block (in accordance with the rules of the PUE) it is allowed to "plant" no more than two wires of the same diameter. Otherwise, the contact will be bad, and the wires simply will not shrink.
Terminal blocks are often referred to as screw clamps, terminal clamps, terminal clamps, terminal blocks, or terminal blocks. All these are the names of the same attribute, and the specific name is formed based on the location of the terminal block.
The product allows the connection of single-core wires with multicore. In this case, both wires must be attached on different sides of the box, on different screws. As a rule, terminal blocks are carbolite, however, this dielectric is quite fragile, so carbolite has been replaced by more reliable analogs made of plastic. The products are mainly used for the installation of lighting equipment, household outlets, for connecting circuits of the terminal for protecting power lines.
Today, several types of terminal blocks are distinguished:
- mounted;
- designed for installation in a junction box ;
- designed for mounting a circuit breaker.
In addition, terminal blocks come with screw and spring clamps.
Materials for creating the product are also used different. Pads come in polyethylene and are used quite widely. Their peculiarity is considered to be low cost and separation of live parts with the help of physical impact (for example, with a knife). In the block body there is a special hole for hard mounting. Most often, in polyethylene pads, all live parts are made of brass, as this is a pretty good and inexpensive conductor.
Basically, this product is used to connect wires when installing lighting devices and installing junction boxes. In addition, terminal blocks made of polyethylene are applicable for wiring outlets for household appliances.
Modern terminal blocks are often made of polyamide. This material is used in professional equipment, for example, in branded protection terminals or important control boxes for controlling high voltage equipment.
Polyamide is used consciously in such circuits, because these terminal blocks are quite expensive, but of high quality. They are resistant to external influences, as well as resilient and are characterized by high electrical resistance. Which, unfortunately, does not have polyethylene analogues.
Polyamide is characterized by a
high breakdown
voltage , a huge resistance to stray surface current, a markedly expanded temperature range at which the material can be used. In addition, self-extinguishing is characteristic of polyamide terminal blocks, since the material is practically non-combustible, and there are no halogen impurities in the composition.
Typically, polyamide blocks are made with live parts made of brass, which are coated with a galvanic film.