On how strong and reliable the electrical connection is, its safety and durability depend. Good contact between the wires gives a stable and even voltage without short circuits and surges. But if sometimes you can do with the usual twisting, then in most cases this approach is unacceptable, and you must use the terminal blocks to connect the wires. "Why?" - you ask. Let's figure it out.
Why is the terminal block better than twisting?
Many electricians, among whom are very qualified and experienced specialists, say that ordinary twisting is better than any comb. This statement is true, but only partially. The fact is that a lot depends on what equipment we are dealing with, what material the connected wires are made of, and also on other factors. This may seem like a trifle at first glance, but in reality everything is somewhat different.
We mention one interesting fact. The rules for electrical work state that twisting in any joints is prohibited. For this simple reason, any tragedy that occurs due to the fact that you used a forbidden connection will happen through your fault. In addition, the rules for the installation of electrical installations (PUE) allow only 4 types of connections, some of which we will discuss in this article.
What is a terminal block?
The terminal block is a special device that is a screw clamp or block. It is used to securely connect wires. There are a huge number of sizes of modern combs. But it is worth noting that the terminal blocks for connecting wires are used to conveniently fix the cable without causing damage to it.
There are several methods for fixing the wire, the most popular one is fixing under the screw head. Forced pulling through screw connection plates is also used. As a result, a very reliable contact can be obtained without causing mechanical damage to the wire.
In some cases, terminal blocks for connecting wires have special terminals. A cable is inserted into them, which is then connected to an electrical cabinet or any other equipment. Such combs are called bushing.
Screw terminal block and its description
You can talk about the scope of screw combs indefinitely. In fact, these are the most popular terminal blocks, the design of which is reliable and at the same time simple. This kind of device is used not only for breeding wiring, but also in outlets. They are also used as a clamp for battery terminals , connecting groups of fixtures and much more.
As for the manufacturing material, screw terminal blocks for connecting wires are most often made of polypropylene and polycarbonate, but sometimes they are made of polyamide and polyethylene. You must understand that this kind of device is not suitable for working with aluminum wires. This is due to the extreme fragility of the latter, so when secured, you can damage them. But for copper and other wires, this is just what you need. Often, a screw terminal block is made grounding. In this case, it has a green screw as a designation, as well as special teeth for efficient grip of the wire.
Clamp connection
The screw terminal blocks that we reviewed are one of three types of wire connection devices. According to the PUE, it is also advisable to use self-clamping terminal blocks. They are used for fixing and connecting wires with a cross-section of no more than 2.5 mm at a current of 24 A. Such a comb can withstand a load of about 5 kW. If the equipment is more energy intensive and powerful, then another method will be required.
It is interesting that it is possible to connect terminal blocks of this type to 8 wires, for which there is an appropriate number of sockets. This decision contributed to the fact that it turned out to significantly accelerate the wiring.
The above method has one drawback. It concerns the occupied space in the junction box (and that is only in comparison with twisting). The level of safety and reliability of the contact in this case is much higher if you do not exceed the permissible load. Otherwise, connection by terminal blocks of this type can be ineffective and even dangerous.
Insulating terminal blocks for electrical wiring
The connecting insulating clamps (PPE) are similar in appearance to a plastic cap. They are made of non-combustible polymer, which eliminates spontaneous combustion due to temperature increase. We can say that their main purpose is protection against fire. Nevertheless, PPE have a positive effect on the quality of the connection by providing reliable mechanical contact. To do this, they must be twisted in a twist in the direction of twisting the wires in the cable. As a result, a spring located inside the housing compresses the wires of the wire, thereby improving contact. Processing twisting with a special paste will avoid oxidation.
If terminal blocks are used for wiring of this type, then it becomes possible to reliably connect wires of various diameters. You can also create contact between the copper and aluminum wires. In addition, the spring has a constant effect on the fixed wires, so there is no need for periodic inspection, as is the case with screw connections.
It should be noted several significant advantages of PPE, which consist in obtaining a quick and reliable connection that can be made even by a novice.
Briefly about power terminals
We can say that the power terminal block has a more complex and cumbersome design than the above options. This is due to the fact that such a device allows you to connect wires of large cross section and power (usually we are talking about a wire from 35 to 300 mm square). They are installed on a special circuit board or din rail, so they are often sold in several versions at once. The contact plate is copper, coated with tin alloy. The clamp has conical washers, which completely prevents contact loosening. Sometimes the power terminal block allows you to install a couple of additional jumpers on adjacent terminals, which is very convenient.
Barrier and universal terminal blocks
A distinctive feature of the barrier terminals is that they have small metal strips in their construction. The latter are separated by an insulating layer. It will be a good distribution terminal block, since it completely excludes contacting of neighboring wires. High quality also determines that each wall has a pair of screws. They are needed for reliable fastening of contacts.
It is precisely the terminal blocks that are installed in the junction boxes, as they are very convenient and reliable. Universal combs are a distribution block with a metal tube, each of which is equipped with a pair of screws for securing the wires. This is very convenient when it is necessary to branch the wiring.
Conclusion
Now you know what terminal blocks are for connecting wires and what types they are. It should be understood that such devices can make the connection not only durable, but also, more importantly, reliable. Currently, there are a huge number of terminal blocks on sale. Some are suitable for small wires, others for large wires. There is a screw, screwless or screw terminal block. Everyone has their own strengths and weaknesses. For this simple reason, the choice should be justified, only then can we hope for a positive result.