Recently, the most popular are connecting insulating clamps (PPE), designed to connect wires. The use of such caps does not require special skills, knowledge, materials and tools, which greatly facilitates and accelerates the workflow. Despite the convenient and quick installation, the clamps have their drawbacks and limitations of use. The presented review of connecting insulating clamps describes the features of caps, their design, purpose and varieties.
Appointment
Insulating caps (PPE) are used to connect two or more conductors and ensure reliable contact isolation. There are several standard sizes of clamps with the corresponding range of the total cross-section of the switched conductors. On the package or in the passport the range of maximum and minimum values of the section is indicated.
The advantage of insulating caps is the possibility of their repeated use.
Design Features
Connecting insulating clamps consist of a metal core and a housing:
- For the manufacture of the body non-combustible materials are used - polyvinyl chloride, polypropylene or nylon. On the housing of the PPE there are special ribs and protrusions that facilitate the twisting process during installation.
- The core is a cone-shaped crimp spring that crimps the twist and provides reliable contact. It is made of steel coated with a protective electrochemical layer. The largest spring corresponds to the area of the smaller part of the housing, in which the wires are in maximum contact with each other. For this reason, it is important to choose the correct cap sizes according to the cross-section of the wiring.
Caps are used for twisting cables in the process of wiring in public and residential premises. PPE can be used in industrial buildings, however, in a wet, explosive or chemically active environment, the connecting electrical unit must be located in a box with an appropriate level of protection.
Features
The main advantages of connecting insulating clamps are the quick and easy installation work without the need for additional tools and materials.
The cap not only insulates the connection, but also protects it from mechanical defects.
The clamp performs an insulating function with proper installation, which eliminates the need for other insulating materials.
The connection created using SIZ-3 is convenient in operation and has compact dimensions. In addition, it is possible to parse the connection: if necessary, the cap is unscrewed, wires are pulled out of it and twisted again.
Benefits
A practical and convenient clamp has additional advantages:
- Affordable cost.
- Zeroing the probability of fire wiring. This property is ensured by special non-combustible materials used to create clamp caps and providing perfect insulation with their use.
- Simple and quick clamp mounting.
- A wide range of color caps, which allows you to mark wires that are not marked by color. As a rule, phase and zero are marked with standard shades.
disadvantages
Along with the advantages, PPE caps have certain disadvantages:
- The cap may fly off the twist after installation, if its size is not selected correctly.
- Connecting insulating clamps must not be used when installing street electrical wiring.
- The caps are designed for switching only cables and copper wires. It is extremely rare to find special clamps for aluminum wires, characterized by the presence of antioxidant paste inside the case.
- Caps do not provide a sufficiently tight connection of wires.
How to choose caps
The number of combined conductors and the total cross-section affect the size of the connecting insulating clamps. The manufacturer often publishes special tables, according to which the sizes are selected. In such documents, two parameters are indicated - the maximum and minimum total cross-section of all the wires to be combined:
- From 1 to 3 mm 2 for SIZ-1.
- From 1 to 4.5 mm 2 for SIZ-2.
- From 1.5 to 6 mm 2 for SIZ-3.
- From 1.5 to 9.5 mm 2 for SIZ-4.
- From 4 to 13.5 mm 2 for SIZ-5.
In the product passport, the clamp size is necessarily indicated. When choosing a cap, the total cross-section of multicore cables connected using PPE is necessarily calculated. The total value should be in the middle of the range of a particular product.
Wiring Preparation
Before connecting multicore cables with the help of caps, the cores must be cleaned from the insulating layer. This is done with a construction knife, but very carefully, since there is a high probability of damage to the conductive core. The knife should not be located at right angles to the conductor, otherwise it can lead to deformation of the core and its breakage.
You can remove the insulation with a stripper - a tool popular among electricians with a large number of functions. The device is equipped with holes with a cutting edge calibrated for conductors of any section.
For the wires to be connected, the insulation layer is removed to the same length. The exposed conductors should not protrude from under the cap body after it has been installed, and therefore it is necessary to accurately measure the length by which the wires are stripped. To do this, just put a clip on the cable and mark the place of the cut - it should be slightly less than the length of the cap body itself. Many manufacturers in the passport or on the product indicate a specific cut length - from 10 to 12 millimeters.
How to use insulating connection clamps
The connection of wires using caps can be carried out in two ways: with or without preliminary twisting.
The twist option involves twisting the stripped wires from the place where the insulation layer begins, and then clockwise. Manual twisting can be done on small wires. When connecting two or more cables of large cross-section, it is best to use pliers. The tip of the finished twist is cut at an acute angle.
When using the method without twisting, it is enough to fold the connected wires parallel to each other so that their end forms an acute angle. This tip is made due to the fact that the spring inside the cap is made in the shape of a cone.
The cap of the connecting insulating clip is put on top of the folded cables and scrolled clockwise until it locks. While screwing the cap, the spring tightly compresses the wires and twists them.
If the stripped insulating layer is longer than the clamp body, and the bare veins protrude from it, then they are insulated with varnish, insulating tape or adhesive tape, creating an additional winding.
Usage Tips
- Correctly selected caps corresponding to the twist section will not fall from insulated wires.
- Electricians and specialists advise, after installing the clamp, to check the insulation of the electrical connection unit. For thirty minutes, the maximum load is applied to the circuit, after which the temperature of the insulating cap is measured. If the element does not heat up, it means that the installation was carried out correctly and the wiring is functioning correctly. As the temperature rises, the insulating connection clamp is disassembled for diagnostic purposes.
- Clips cannot insulate aluminum and copper contacts. For this purpose, other elements are used - terminal blocks, self-clamping terminal blocks and special adapters equipped with metal plates.
- The PPE cap is wound on twisted wires with a little effort, which allows you to create the necessary contact density. Excessive pressure and force should not be applied, since there is a risk of breaking the crimp spring.
- Caps of insulating clamps are not classified by color, moreover, the shade is not specified, in connection with which multi-colored products are used for aesthetic purposes and for the convenience of an electrician. Many masters, for example, equip phase wires with a brown cap, zero wires with blue, earth wires with yellow or green.
- The insulation from the conductors must not be removed for a long length - it must necessarily be identical to the length of the cap.
It is rational to use connecting insulating clamps when connecting live cables in a junction box or when installing lighting fixtures.