If it is carried out by twisting, it is necessary to make reliable and strong contact of the surfaces of the conductors for better electrical contact. This can be achieved due to the force applied during twisting, however this type connections lose their strength over time due to metal fatigue, as well as as a result of thermal expansion and contraction. But according to clause 2.1.21, it is prohibited to use twisting. This method is only possible in conjunction with special connecting insulating clamps (PPE). In this article we will look at how to use PPE caps, what sizes the products come in and what are the advantages of these connectors.
Cap design
The design of the device includes the following components: a cap and a steel spring. The PPE cap is made of plastic, which has electrical insulating properties. This plastic is non-flammable and resistant to high temperatures, and can also withstand a voltage of 600 Volts. These indicators are usually written on the packaging.
As for the spring, it is made of steel in the form of a cone and, with the help of coils, compresses the wire more strongly. The steel spring is additionally treated with electrochemical protective layer. The dimensions of the spring should be equal to the area of the smallest part of the body where the wire will have maximum contact with another conductor. Therefore, it is extremely important to choose exact dimensions so that the connection is as correct and reliable as possible.
It is worth noting that PPE caps come in two types - with ears and without ears. There are no special differences, but caps with ears are easier to screw onto the wire, while caps without ears take up less space in the junction box.
Rules of application
There are two methods of twisting using PPE caps: without preliminary twisting of the cores and with it. If it is necessary to connect two conductors, then they can be conveniently inserted into the spring, applying a certain force, and using rotational movements(clockwise) twisting is carried out. If there are three or more conductors, then you must first twist them together using pliers. After this, bite off the uneven ends and, using force and rotating movements, install them into the PPE, as shown in the photo:
It is important to remember that for full contact contact, winding should be done clockwise, not vice versa. And do not forget about using force so that the coils of the spring move apart easily and then squeeze the wire well.
The plastic housing insulates the place where the connection was made and thereby mechanically protects the conductors. The insulation from the conductor should be removed taking into account that the exposed part does not extend beyond the cap, but at the same time extends as far as possible under the spring. If everything is done correctly, then additional insulation is not needed.
When the PPE is twisted, the spring expands and compresses the wire. This connection will work correctly if the correct cap is selected that matches its rating. If you choose the wrong device or install it ineptly, this can lead to bad consequences. Therefore, it is extremely important to choose the right category.
The video below clearly shows how to use the connecting insulating clamps:
Connector markings
How to choose a cap? After all, their sizes and twist sections are different and are classified according to the total cross-sectional area of the cores. This area is indicated by the connector number, which can be from one to five. The higher the number, the more wires the cap can connect.
But you need to be careful with such numbers, since there are two types of devices: domestic and European. The designation for both standards is the same - numbers, only European denominations are much smaller than domestic ones. Therefore, when buying PPE, it is better to pay attention to the total cross-section than to its number. All this is written on the packaging.
Product marking is carried out as follows: first, the abbreviation PPE is written down, then the type of body is marked (with or without protrusions). The protrusion is necessary for better fixation of the clamp with your fingers. After the housing type, the total cross-section of the wires that are connected in the clamp is written down. The cross section ranges from 0.5 to 10 mm2. As a rule, depending on the type and size of the product, their bodies are painted in specific color to make it convenient to use the caps. The table below indicates color scheme depending on the type of case, which will make it clearer to you how to choose PPE for twisting:
It should also be remembered that caps can only be used when two identical wires are connected. If required, then it is no longer possible to do this using PPE. In this case, you can use a metal clamp (nut) or a bolt.
Advantages and disadvantages
This connector is convenient and practical, therefore it has the following advantages:
- Affordable price.
- There is no possibility. This is explained by the fact that non-flammable material is used for the manufacture of PPE and where the twisting has been done, spontaneous combustion is impossible.
- Fast and easy installation products.
But PPE also has some disadvantages:
- there is no possibility to connect aluminum and copper;
- insufficiently strong fixation and insulation.
To summarize and weigh the pros and cons, I would like to note that it is rational to use PPE connecting insulating clamps when connecting current-carrying conductors in distribution box, as well as when connecting lamps (for example, chandeliers on the ceiling). Finally, we recommend watching this useful video
During assembly electrical diagrams wires need to be connected to each other. An electrical contact is created at the connection point, which has a certain electrical resistance.
The task of any installer comes down to ensuring a strong connection of the wiring with minimal transient resistance and reliable electrical insulation.
For these purposes the following are used:
- twists;
- twists with welding;
- rations;
- screw connections;
- assemblies on terminal blocks and screw blocks;
- self-clamping express terminals from WAGO or REXANT;
- insulating caps for twisting.
In this article we will talk about how to connect wires using caps.
Typically, two main methods are used to properly connect two wires: twisting followed by soldering and regular twisting (without soldering).
But it is worth noting that despite the advantages traditional methods they are also endowed with some disadvantages: soldering being high-quality connection when disassembling, it requires complete removal (“biting off” the soldered part of the wires), which is not always possible due to the supply of wires; twisting increases the chance of oxidation and does not guarantee a reliable connection.
Today there is another solution to such problems - these are connecting ones.
PPE caps for twisting wires
PPE caps- these are connecting insulating clips that are made of non-flammable plastic. Inside these caps there is a conical metal spring.
When they are twisted with a little effort, the spring moves apart and compresses the wires, and the plastic sheath provides reliable electrical insulation, as well as mechanical and fire protection.
PPE caps are conical parts with metal bushings, which have threads inside. By inserting two wires into this part and turning it a couple of times, the wires will be securely connected. If necessary, this connection can be made without the slightest problem disassemble.
Connecting caps are produced different sizes for wires from 0.5 to 1.6 millimeters in diameter.
As a rule, the color of the cap corresponds to the specific diameter and size of the connected wires for which it is intended. Thanks to the use of connecting caps, a reliable connection of wires is achieved without the use of additional tools.
PPE caps are characterized cross section total twisted wires. This cross-section is expressed by the PPE number from 1 to 5. This figure characterizes the cross-section and number of twisted wires.
| Brand | Number and cross-section of cores, mm² | Color |
| SIZ-1 | 2×1.5 | grey |
| SIZ-2 | 3×1.5 | blue |
| SIZ-3 | 2×2.5 | orange |
| SIZ-4 | 4×2.5 | yellow |
| SIZ-5 | 8×2.5 | red |
Accordingly, the larger the number of the PPE cap, the larger the cross-section and number of wires it is intended for.
All wire connections assembled on self-clamping terminals or insulating caps are highly efficient and are gaining popularity.
Express terminals allow you to quickly create reliable connection, but have more complex design, somewhat more expensive. They are more often used to connect conductors to new measuring, automation and protection devices operating on microprocessor circuits.
For everyday frequent use, they are best suited with simple device. The connection of the conductors is achieved by screwing their metal ends into a strong spring made in the shape of a cone-shaped spiral.
There is no need to insulate the connection point; the spiral is placed in an insulated cap. The material of its body does not support combustion, is resistant to aggressive environments, and provides good electrical insulating properties.
Twisting of PPE wires
Installing the cap on prepared wires is quick and does not require special tool. The created connection is compact. The caps are convenient to use. However, you need to know the rules for their use and develop the necessary skills. Inept handling can lead to dire consequences.
Insulating caps are suitable for connecting several wires of a certain diameter, which is indicated in the documentation. Manufacturers from different countries use their own designations. Therefore, it is better to navigate overall dimensions for connecting wires, and not with the manufacturer's markings.
Using PPE caps - practical application
Particular care is required when handling aluminum conductors. Soft metal is easily deformed and quickly loses strength.
At twisted cap aluminum is reliably compressed by a conical spring and works well long time. Due to the occurrence of electrochemical processes, aluminum wires cannot be twisted together with copper wires.
It is important to remove from the conductor optimal length insulating layer to ensure maximum contact area metal parts. It's easy to define. It is enough to insert one wire inside the cap and visually mark the place where the insulation is cut. Remove the insulation and repeat the test installation of the wire. Exposed metal should not extend beyond the insulating portion of the cap.
When removing insulation, use different ways. Many older installers work with a lineman's knife, which has an insulated handle and a short, sharp blade made of durable steel. Wedge or razor sharpening, which removes insulation well, but in inexperienced hands can cause harm.
A knife, especially when directed perpendicular to the conductor, can damage the outer surface of the metal. Any scratch, even a barely noticeable one, will increase in size when twisted, reducing the cross-section of the conductor, reducing it electrical characteristics. The metal will begin to heat up and burn out, especially under heavy loads. A deep cut in the conductor will cause the wire to break when twisted.
You need to remove the insulation with a knife when its blade is positioned at an obtuse angle to the conductor relative to the direction of the cut, using light movements without damaging the metal.
A certain part of electricians use pliers or wire cutters to remove insulation; they deform the metal at the point where the conductor is crimped, which is not acceptable. Insulation can be removed efficiently special pliers, produced for such work.
The method of twisting wires with pliers and then putting on the cap does not ensure reliable contact and its insulation. The caps just fall out over time. But some installers don't understand this.
Taking advantage insulating caps, force must be applied when twisting. It will ensure tight contact between the metals of the conductors and the spring.
To evaluate the effectiveness of using caps before their mass use, it is necessary to connect wires with them and pass a rated current through it with a load device for about half an hour. Analyze the heating of the connection. Then exceed the current and identify problem areas.
These electrical tests help professionals find out weak spots electrical circuits they create, improve their skills, and perform quality work.
To assemble electrical circuits, there is always a need for strong wires and cables between each other.
The following methods of connecting cables are distinguished:
- regular twist;
- twisting using insulating tape;
- twisting using welding;
- connection using blowtorch;
- connection using self-clamping terminals;
- screw connection;
- twisting using terminal blocks and screw blocks;
- insulating caps for twisting wires.
Connecting wires using caps
The most popular of these methods are conventional twisting and soldering of cables. However, they have their drawbacks. Regular twisting does not allow the wires to be securely fixed and increases the chances of their oxidation. It is impossible to solder cables without removing a certain part of the cable, which is not always convenient. There is also such a thing as PUE (electrical installation rules). These rules clearly indicate the ban on the use of simple twisting; wires must be welded or soldered together, and the use welding machine or a blowtorch can take quite a long time.
One of best alternatives Today, PPE caps are used for connecting cables.
PPE stands for connecting insulating clips. The outer part of such caps is made of insulated heat-resistant cone-shaped plastic, which can withstand both high temperatures(for example, when the cable overheats) and low (very convenient during installation electrical wiring in conditions severe frost). Inside the cap there is a metal spring-clamp. When the wires are inserted inside, the spring expands slightly and wraps around the cable, thus securely fixing it inside the cap. The outer part reliably protects the twist from moisture and any mechanical impact.
Inside the caps there is a spiral that compresses the connected wires
Usage
To make a connection using PPE, you must perform the following procedure:
- strip the ends of both wires. Here it is necessary to remove the optimal length of the protective (insulating) layer. It’s easy to find out this length - you just need to insert one wire into the cap and mark the cut location. You can remove the insulation from the wire with a regular knife at an obtuse angle. This must be done very carefully, since the slightest scratch will reduce electrical conductivity, and a large cut can even lead to failure of the entire wiring. Removing insulation using wire cutters or pliers is highly not recommended, as they deform the wire;
- pre-twist the ends in a screw pattern;
- insert the wires into the insulating cap;
- turn the cap a couple of times clockwise.
The cap must be screwed clockwise
Thus, the wires will be firmly and securely fixed inside the cap.
It is strongly recommended to test the caps before using them for operational use. To do this, you need to connect two cables using PPE and test them using a load device for about half an hour at rated current. After this, you need to analyze the heating level of the contact, then increase the current level and identify possible problem areas.
It must be remembered that twisting aluminum wires must be carried out very carefully and carefully, since the metal itself has a fairly low melting point, so it can deform very easily.
Do not join together aluminum and copper wires- the aluminum wire will quickly oxidize and the resulting galvanic couple will destroy the connection.
Classification
PPE caps have the following classification:
- SIZ-1 - designed for two wires with a cross-section of 1.5 mm, gray color;
- SIZ-2 - designed for three wires with a cross-section of 1.5 mm, color blue;
- SIZ-3 - designed for two cores with a cross-section of 2.5 mm, orange color;
- SIZ-4 - designed for four wires with a cross-section of 2.5 mm, color yellow;
- SIZ-5 - designed for eight cores with a cross-section of 2.5 mm, red color.
However, it must be remembered that there are also PPE made in Europe. Such caps are also marked by numbers, but their diameter is much smaller. Therefore, it is necessary to pay attention to the cross-section and number of wires indicated on the packaging.
If you use a twist cap of the wrong size and diameter, there is a high probability that it simply will not be able to fit onto the wires, and if you use too much personal protective equipment big size the cap may fly off and all electrical wiring may fail.
Comparison with analogues
The main analogue of PPE caps are screw terminal blocks. IN in this case The two wires are connected together using a screw. However, this method has several disadvantages:
- The connecting screw must be tightened periodically, since it becomes loose over time and the contact between the cables weakens. This is especially inconvenient if the terminal block is used on an industrial scale or is located in a hard-to-reach place;
- exists on the market a large number of terminal blocks made in China are made of polyethylene shell, which when used can lead to a fire.
In contact with
Purpose
Spring-type cap-type electrical connection clamps (CPE) are designed for connecting two or more cables/wires with copper conductors with a cross-section from 0.5 to 10.0 mm 2 and insulating the connection. For each standard size of PPE, the manufacturer indicates the range (minimum and maximum) of the total cross-section of the connected wires. This type The clamps can be reused multiple times. To make it easier to select a clamp, some manufacturers make them different color– depending on the standard size.
Clamp design
PPE consists of a body and a core. The clamp body is made of plastic (PVC, nylon, polypropylene) that does not support combustion. To make it easier to screw the cap during installation, the body has special ribs or protrusions.
The core of the cap is a cone-shaped metal spring. When the cap is screwed onto the wires, a spring compresses them, making electrical contact.
Application area
These connecting clamps are used when installing electrical wiring for residential, public and industrial buildings and structures. The use of PPE in explosive, chemically active and humid environments without connection (branch) boxes of the appropriate degree of protection is not allowed.
Stages of PPE installation
The connection is ready for use.
Advantages and disadvantages
The main advantage of PPE of the “cap” type is the speed and ease of installation because:
- No application required additional tool and devices.
- No additional insulation of the connection point is required, since the PPE body acts as an insulator.
Disadvantages of cap-type PPE:
- It is necessary to select the correct clamp size, otherwise the cap may fall off after installation.
- Only copper wires and cables can be connected. It should be noted that there are also clamp-caps of a special design (their distinctive feature in that the housing is filled with anti-oxidation paste) for connecting aluminum conductors, but they are rare.
- They have a degree of protection IP-20, so they cannot be used for open street installation.