NSHVI lugs for crimping wires: dimensions, types, how to crimp, other types of TML, NVI and NKI

The use of tips when connecting wires is an opportunity to improve the quality of the contact, thereby reducing the contact resistance and heating of the section during the flow of currents. In addition, the safety of the cable is ensured when it is connected using a screw clamp.

The question is which product is better to use. Today, the following tips for wires stand out – NShVI, TML, NKI, NVI and others. Consider their features, advantages and rules of application.

Decoding and purpose of NShVI

NShVI – type of tip, which is deciphered as follows:

• “N” is a tip.
• “Ш” is pin.
• “B” – sleeve.
• “I” – isolated.

This type of tip is used when crimping copper wires with a large number of cores for subsequent connection to devices and assembling electrical circuits.

Crimping is carried out using a special tool – tongs for crimping NShVI. In other words, the task of the product is to ensure high-quality contact and integrity of the cores when connected using a screw clamp.

Sleeve NShVI are used for copper wires with a cross section in the range of 0,5-35 square meters. mm. Once the product is installed, solid pins are formed at the ends of multi-core cables, making it easy to connect to a terminal or equipment.

Where are they used and what will happen if end sleeves are not used?

Connecting stranded copper wires without the use of NSHVI leads to damage to the cores, deterioration of the contact connection and subsequent burnout. In addition, damaged cores are subject to oxidative processes and rust faster.

Tips NShVI (KVT) have a wide scope. They are actively used when connecting sockets and switches, installing automatic machines in an electrical panel, connecting RCDs and other equipment.

The popularity of a multi-core cable is easy to explain, because it has a number of advantages – flexibility and the ability to pass more current through itself (when compared with a single-core wire of the same cross section). But it is not suitable for screw connection. It is these clamps that are used today in the same AB, switches and sockets.

If you act without clamping, the strands are displaced by the pressure of the screw and damaged. As a result, the reliability of the connection deteriorates and the quality of the contact decreases.

Previously, soldering stranded wires was used to solve the problem, thanks to which a large number of cores became one.

The downside of this method is that it takes a lot of time. If you need to install a dozen sockets and switches, more than one day will go to work. The use of NSHVI allows you to avoid such problems and speed up the work.

During the installation process, it is worth remembering that the cross section of the wire and sleeve must clearly correspond to each other and be selected taking into account the manufacturer. This is the only way to avoid installation difficulties and damage to the cable. You can be sure that the connection will last for the entire time of operation.

Design and types

The product consists of 2 elements:

• CONDUCTING TUBE. In the process of its manufacture, electrolytic copper with obligatory tinning is used.
• POLYAMIDE FLANGE, INSULATED.

In simple terms, NShVI cable lugs are copper tubes processed by electroplating and having one flared end (for inserting a stranded conductor). The second part of the product is a polyamide cuff that provides reliable insulation and voltage protection.

A special type of copper is used in the manufacturing process, which ensures a reliable connection at the point of contact and avoids damage to the conductor due to screw pressure. Today you can buy a NShVI tip with a cross section of 0,25-150 mm.

According to the design of the device, there are two types:

• Single.
• Double.

The first are designed to crimp one, and the second – two stranded wires at the same time. This is their main advantage. For example, when power is applied to the AB (circuit breaker), it is possible to exclude an additional wire jumper from the circuit. Based on the characteristics of each type, the size of the plastic flange varies.

In addition to the type of product already considered, there are other types:

Design nuances and characteristics

The NShVI tip, as a rule, has the following features:

• In the manufacturing process, copper type M1 is used;
• The upper voltage threshold is 690 V;
• The connector surface is subjected to electrolytic tinning;
• The dimensions of the connectors are designed for connecting one cable (installation is carried out taking into account the cross section);
• Insulation is carried out using polypropylene, which does not contain halogens;
• The insulating element is characterized by high thermal resistance – it can withstand temperatures up to 105 degrees Celsius;
• KBT sleeve connectors are manufactured in one color and have a common DIN standard. This is done in order to eliminate difficulties during the installation process. In addition, the color is selected taking into account the marking DIN 462228, part 4.
• The conductor is crimped on top of the copper sleeve;
• Cuff NShVI has a conical shape, which eliminates problems in the process of inserting a stranded wire into the inner part of the sleeve.

Product specifications are shown below.

Working methods

When using NShVI tips, the following should be considered:

COLOR “SKIRTS”. The product shows the section of the connector. As a rule, we apply the KBT standard, which is characterized by the following:

• Black – 1,5 sq. mm;
• Blue – 2,5 sq. mm;
• Gray – 4 sq. mm;
• Yellow – 6 sq. mm;
• Red – 10 sq. mm.

It is worth noting that goods from stores deviate from the standard. At the same time, the size of the product and the color do not correspond to the CBT. Minus – in low quality and rapid destruction. That is why, when choosing, you should pay attention to the color of the “skirt” and its compliance with the section.

PACKAGE. As a rule, NSHVI for pressure testing come in packs of one hundred products, which are packed in five pieces in a larger package. It is not possible to purchase such a product by the piece.

If you need to connect two cables, you should not “reinvent the wheel”. NShVI-2 connectors of the same type of installation are on sale. For example, if you buy a product for four square meters. mm, it easily accepts two wires per 4 sq. mm.

Crimping tools and their disadvantages

There are two types of tools used for crimping:

Popular crimping tool

The following tool is used to install KBT tips:

• WS-04A – the best pliers for beginners. With their help, it is possible to solve the main set of tasks in the process of installing various electrical circuits and assembling shields. Its functions include the ability to bite off and strip wires (cables) having a cross section of up to 10-16 square meters. mm. In addition, it provides recesses for NShVI tips up to 6 sq. mm. (if desired, a cable up to 10 “square” is included) or up to 10 square meters. mm. (includes up to 16″ square). On sale you can find WS-04A tongs, which provide dies for crimping NShVI. Their minus is that the matrices can only cope with products of standard sizes up to 6 “square”. If you use wires with an underestimated cross section (fake), the connection quality will be poor.
• PKVk-10 – a universal tool that is used to crimp conductors of 0,5-10 sq. mm. But this is in theory, because in practice the situation is different. For example, a large force is required to crimp a cable from 6 “square” and higher, and if the crimping force is reduced, the quality of contact when crimping connectors with a small cross section deteriorates. The advantage of PKVk-10 is its compactness and the ability to crawl even into a hard-to-reach place for installation (if necessary). The tool is best used for crimping conductors up to 4 “square”.
• STK-03 – powerful pliers that are suitable for large sections (from 10 to 25 “square”).
• PC-16. Such tongs are useful for crimping TML from 6 to 10 square meters. mm. The manufacturer sets an upper limit of 16 square meters. mm., but in practice, crimping such a cable requires a strong hand and a lot of effort. In general, the tool is not very good, but it has an affordable price. On sale there is a version of the PK-16u – a reinforced version, which is more durable. The tool is suitable for cases where crimping is rarely carried out.
• PGRs-70 – hydraulic press, which is used for TML and sleeves. Many consider the tool as an alternative to the PC-16. The peculiarity of the press is the availability of interchangeable dies with different cross-sections in the range of 4-70 sq. mm. With the help of such equipment it is convenient to crimp classic cables – by six, ten or sixteen square millimeters. It does not require a large load and excessive effort.
• PKVsh-6 – used for crimping NShVI and NShV from 0,25 to 6 sq. mm., as well as a double tip NShVI-2 with a cross section from 0,5 to 4,0 sq. mm.

As for the Wiedmuller or Knipex pliers, their disadvantage is the large divergence of the handles. As a result, it is difficult to crimp the NShVI with one hand (the length of the fingers is not enough).

To avoid discomfort when performing work, it is worth choosing a tool from the position of ease of use, and not focusing on the brand.

How to crimp NShVI end sleeves?

Before crimping, the wire is stripped using a stripper, a special knife or a stripper. The first option is the most convenient and allows you to quickly get rid of the top insulation without damaging the cores. Stripping is carried out clearly along the length of the sleeve into which the conductor is installed.

As soon as the preparatory work is completed, a sleeve is put on the insulated part. Pre-select a pin sleeve lug (NShVI) of the required length.

When crimping, special tongs are used, which were mentioned above. In the process of doing the work, it is important to know how to use the press tongs. If you violate the technology, the quality of fixation leaves much to be desired.

To avoid errors, the sequence should be like this:

• Introduction of the cleaned edge into the sleeve;
• Installing the tip in the groove of the tool. It is important to ensure that the insulated part is pressed tightly against the body of the pliers;
• Clamping the handle with sufficient force to ensure a secure fit of the connector.

If everything is done correctly, a reliable connection is obtained, and the structure itself is monolithic and strong. The principle of crimping using NShVI-2 is similar. The main thing is to accurately select the cable section. It’s easy to do. The first digits show the section, and the subsequent ones (indicated with a hyphen) show the length of the working part.

WS-04A, which was mentioned earlier, is considered the optimal crimping tool in terms of price-quality ratio. Its peculiarity lies in the presence of lower teeth, which ensure reliable crimping of the product. Thanks to the groove, the connector is tightly compressed and cannot be removed.

During the installation of NShVI, consider one nuance – use the section one step below. What does it mean?

For example, if for a cross-module the allowable cross-section of a stranded wire is indicated, equal to 16 sq. mm., after crimping a 16-mm analog with the help of NShVI, the design will not fit into the connector. Here it is worth using a cable of 10 square meters. mm.

The PKVk-10 tool is considered no less convenient, but it is used for smaller sections. After crimping, the connector has a rectangular, and not trapezoidal (as in the previous case) shape.

The advantages of the tool are reliability and ease of use, but even with it there are “punctures” in the form of poor-quality crimping (this nuance should be controlled when doing work).

Clamping wires of different sections into a common lug

The most difficult task during installation (especially for beginners) is to combine conductors of various sections in one connector. To avoid problems, you should adhere to the following rules:

• Wire of larger and smaller cross section are diverted from each other. This can be done due to the different insulation of the conductors, as well as the diameter margin of the tip skirt. A thinner product is stripped a greater distance, after which it is shifted forward so that it is the first to end up in the tip.
• At the second stage, the main wire is inserted into the ferrule until it stops and crimping is performed.

By a similar principle, it is worth acting in the case of double NShVI – first a thin conductor is started, and then the main wires are inserted. It is recommended to use STK-03 pliers for crimping. In the process of work, make sure that the tool does not snap into place. To do this, hold the ratchet lever while crimping.

What to do if there is no crimper on hand?

The situation is more complicated when there is no special tool for crimping NShVI. Here you have to look for alternative crimping methods so as not to disrupt the workflow. One option is tinning with a soldering iron, rosin and tin.

This option is good, but not suitable in all cases. In addition, the work takes time, and with large amounts of work, running with a soldering iron from one place to another is inconvenient.

Some “masters” use ordinary pliers for crimping. The essence of the technique is to press on the tip in several places for reliable fixation. The convenience of the method is undeniable, but when using it, there is a risk of damaging the cores. If earlier this method of installation was acceptable, today it is better to forget about it.

If there is not enough money for an expensive crimper, you can buy a more affordable tool. There are many mites on sale that have decent performance in the price-quality ratio. In addition, it is better to take universal tools that can perform several functions at once.

Double insulated tips (NShVI-2)

To crimp two stranded conductors, a special connector is used – NShVI-2. Its advantage lies in the ability to connect two wires at once, included in one socket of an electrical device.

In addition, if you need to install several conductors of the same section (for example, 4 by 1,5 sq. Mm.), It is also better to use NShVI-2.

It is useful in cases where it is necessary to separate the lines in the shield to different terminals or, for example, to connect a neutral wire with an RCD or AB to several terminals at once. Using a jumper in this case will not work.

Popular products in Russia

There are many factories producing NShVI tips in Russia. The leading position in this market segment is occupied by the KBT plant, which produces electrical installation tools and cable fittings, which are of high quality and affordable prices.

Today, the plant’s product range includes more than four thousand items, which allows you to choose the right tool and accessories.

The plant produces the following products:

• Cable lugs and sleeves designed for crimping wires and cables.
• Bolt lugs and connectors – for easy installation of cable cores. The peculiarity lies in the versatility and reliability of the contact, which allows the product to be used as component materials for heat-shrinkable cable sleeves.
• Insulated tips, sleeves and connectors.
• Insulated clips and terminals.
• Couplings cable KBT.
• Elements of cable joints and other items of equipment designed to work with wiring.

At the end of

The use of NShVI and other types of lugs is mandatory if a multi-core cable is used to connect electrical appliances and equipment.

Ignoring this requirement and installing the cable under the screw clamp without a sleeve leads to a deterioration in the quality of the connection, heating of the contact point and burnout of the conductor.

In the absence of special pliers, tinning of the stranded wire with a soldering iron is used; alternative crimping methods are not justified.