PPE twisting: insulation of electrical wires with caps, design features of twists

During operation, any wires are exposed to stress and heat. Therefore, for a high-quality supply of an enterprise or a private house with current, a tight contact between the wires is necessary. This can be achieved by twisting PPE or connecting insulating clamps. They are called caps for short because of their appearance.

Ways to align wires

To assemble an electrical circuit, you need to ensure reliable contact between the cable cores. For this, several options are used:

• Simple or isolated stranding.
• Application of welding or soldering iron.
• Using screws and nuts.
• Through terminal blocks or strips.
• Self-clamping elements of the Wago type.
• Insulating caps.

Plain twist and weld are the most popular of these. However, these methods are not without their drawbacks. The first of them does not imply a rigid fixation of the wires, as a result of which the contact can weaken, there is a possibility of oxidation and destruction of the ligament. To make a connection in the second way, it is necessary to use special equipment, which may not be at the installation site or its use will be inconvenient.

In addition, according to the Rules for the Installation of Electrical Installations (PUE), it is prohibited to connect wires using twists. In emergency situations, there may not be enough time to prepare the welding or soldering equipment. Therefore, it is necessary to provide for alternative options that meet the rules and regulations.

Using the caps

This method does not require special skills from the employee and the use of additional devices. In addition, the speed of creating a connection of cores using this method is quite high to perform prompt installation work. PUE allows the use of electrical PPE in various installations.

Appointment of the device

Such clamps are of the spring type and are designed to mate two or more conductors providing the necessary contact and reliable insulation. Despite the fact that the Rules do not clearly regulate the operation of such devices, GOST 50043.1-92 establishes their compliance with safety requirements.

Some electricians talk about cases from practice where PPE caps did not perform well. However, there are explanations for this:

• Insufficient qualifications of the installer himself.
• The use of low-quality products of dubious origin.
• Incorrect calculation of the wire cross-section relative to the load on the power grid.

If all work is carried out according to the instructions using quality materials of appropriate sizes, then when protecting the line with circuit breakers, such connections will last a long time without additional service.

The use of such clamps is possible not only in residential premises, but also in production. However, in places with a chemically active environment, high humidity, it is necessary to place the structure in branch boxes of the appropriate degree of protection.

Do not use electrical PPE when connecting conductors made of dissimilar metals. Copper and aluminum conductors should be emphasized. During heating, galvanic processes occur between them., destroying the contact density. In this case, it is advisable to adopt steel transition terminals with conductive treatment.

Constructive execution

These connectors are reusable. They are made very simply. Any PPE insulating cap for twisting wires consists of a body and a spring. The first is made of flame retardant plastic. It can be nylon, PVC, polypropylene. For the convenience of handling the clamp, its surface is ribbed or with special notches. The sheath has a protective and insulating function.

The core is a metal crimp spring. It has a conical shape. When the cap is screwed onto the twist, it is pulled together, providing reliable contact.

The dimensions of the spiral deserve special attention. In order to choose the correct cap, you need to know the cross-section of the wires to be connected and the smallest base of the cone in which their contact will be created. If the wire is thinner, then it will not be possible to squeeze it, and the thick one simply will not fit into the cap.

To put the crimp on the twist, you need to press it harder to push the spring coils apart. The body must be rotated clockwise. By performing these simple manipulations, you can create a tight connection of cables.

Product classification

Many caps for soldering conductors of various manufacturers are sold on the Russian market. Domestic standards provide for the following standard sizes similar electrical products:

• Gray for double-strand twisting. The cross section of each core is 1.5 sq. mm. It is labeled as SIZ-1.
• SIZ-2 connects three wires of the same size and is colored blue.
• For 2.5 mm conductors in the amount of 2 pieces, there is an orange PPE-3.
• Four of these wires will fit into the yellow PPE-4.
• Eight veins with a size of 2, mm square in diameter will be removed in the red PPE of the fifth number.

It should be noted that such names correspond to products of domestic manufacturers. Imported caps, despite the similarity of designations, have a slightly smaller size. Therefore, when buying, you should carefully read the labels on the packaging.

Method of working with PPE

The main requirement for the manipulation of caps and wires is the correct size. The quality of the contact depends primarily on this. In order to make the right choice, it is necessary to add up the cross-sections of the veins planned for twisting and select the required device according to the table. It is necessary to focus not on the extreme values ​​of the indicators, but on the averaged ones. In this case, the most tight contact is ensured.

Further, all the work can be performed in two ways:

• Align the wires and place them in the cap without preliminary twisting. Then press firmly into the housing and turn clockwise until the spring engages. If there is a lack of hand force, you can use pliers or a screwdriver, for which a special attachment is sold that does not damage the clamp shell.
• The veins can first be cleaned and twisted together, cut off the tip and screwed on with PPE.

The choice of method depends on the thickness of the wire. Thin ones, for example, in half a square, will not be difficult to connect, but more powerful, 2.5 square millimeters, exert a high load on the spring and often break it.

Twist length

Manufacturers recommend stripping equal to the depth of the cap or slightly less. This will be approximately 10-12 millimeters. Longer tips do not seem to affect the quality of the pairing, but this should be done with a large number of wires being connected. If the size of the exposed part is small, then it will not be possible to create the desired area of ​​contact for all participants in the twist.

If the bare part of the wires peeks out from under the clamp body, then it should be wrapped with electrical tape. And although the very name of PPE in this case will not be entirely correct, the reliability of the pairing is provided precisely by the cap, the wires will not weaken when heated under load.

Advantages and disadvantages

Insulating devices have a major positive feature in their application. It consists in the fact that due to the plastic case, they perform three functions at once:

• Electrical insulation.
• Fire protection.
• Resistance to mechanical damage.

It is important that, unlike sleeves and tips, PPE can be easily turned counterclockwise and reused. There is a possibility of correcting an erroneous connection without changing the wire length. This quality is widely used when arranging temporary huts or connecting portable electrical equipment.

Many complaints from firefighters are caused by twists in the distribution boxes on the power lines. The caps solve this problem. It is enough just to open the branch point, remove the old insulation and screw on the cap. Such a connection will not elicit the comments of the checking inspector.

One of the main disadvantages of such products is the impossibility of using them with stranded wires. This installation method is prohibited. It is also not recommended to splice aluminum conductors. Some manufacturers explicitly indicate on the packaging that the scope of their products is copper cables.

Causes criticism and tightness of such a twist. In high humidity conditions, the spring rusts and becomes unusable, destroying the contact between the veins. This problem can be partially solved with electrical tape.

Another inconvenience is associated with the size of the product. If there are a lot of wires, not every junction box can accommodate several caps. However, due to the convenience and ease of installation, the economy and durability of the connection method, many go to replace the distributor.

Clamp analogs

The main competitors of such devices are terminal blocks. In this case, the two wires are tightened with a screw. However, this method has several disadvantages, among which the weakening of the contact is distinguished, which requires constant monitoring and periodic tightening. If the device is in an inconvenient place or their number is large, then this is very costly, both in terms of effort and time.

Another weak point of these connectors is the pad material. There are many Chinese cheap polyethylene products on the market. It cannot withstand even light heat and melts or ignites, which can lead to a fire. Therefore, the use of PPE caps is quite justified both at home and at the factory.