PPE caps: is it worth using. Connecting insulating clamps PPE (KBT) PPE electrician that

Purpose

Cap connecting electrical clamps (PPE) of spring type are designed to connect two or more cables / wires with copper conductors with a cross section of 0.5 to 10.0 mm 2 and insulate the connection. For each size of PPE, the manufacturer indicates the range (minimum and maximum) of the total cross section of the connected wires. This type of clips can be used repeatedly. Some manufacturers make clamp selection easier. different color- depending on the size.

Clamp design

PPE consists of a body and a core. The clamp body is made of flame retardant plastic (PVC, nylon, polypropylene). To facilitate the screwing of 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 strands, the spring compresses them, providing electrical contact.

Application area

These connecting clamps are used in the installation of electrical wiring in residential, public and industrial buildings and structures. It is not allowed to use PPE in explosive, chemically active and humid environments without junction (branch) boxes of the appropriate degree of protection.

PPE installation steps

The connection is ready to use.

Advantages and disadvantages

The main advantage of PPE of the “cap” type is the speed and ease of installation, since:

No application required additional tool and fixtures.
Additional isolation of the junction is not required, since the PPE body acts as an insulator.

Disadvantages of cap PPE:

It is necessary to choose the correct size of the clamp, otherwise the cap may fall off after installation.
Only copper conductors of wires and cables can be connected. It should be noted that there are also clip-caps of a special design (their distinguishing feature in that the case is filled with antioxidant paste) for connecting aluminum conductors, but they are rare.
They have an IP-20 degree of protection, so they cannot be used for outdoor outdoor installation.

For Assembly electrical circuits there is always a need for durable wires and cables between each other.

There are the following ways of connecting cables:

ordinary 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 with caps

The most popular of these methods are the usual twisting and soldering of cables. However, they have their drawbacks. Normal twisting does not allow you to securely fix the wires 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 prohibit the use of simple twisting, the wires must be welded or soldered to each other, and the use of a welding machine or a blowtorch can take a lot of time.

One of the best alternatives for connecting cables today are PPE caps.

PPE stands for connecting insulating clamps. The outer part of these caps is made of insulated cone-shaped heat-resistant plastic, which is able to withstand both high temperatures(for example, when the cable overheats), and low (very convenient for installation electrical wiring in conditions hard frost). Inside the cap is a metal spring-clip. When the wires are inserted inside, the spring expands a little and wraps around the cable, thus fixing it securely inside the cap. The outer part at the same time 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 optimal length protective (insulating) layer. Finding out this length is easy - you just need to insert one wire into the cap and mark the place of the cut. You can remove the insulation from the wire with an ordinary knife under obtuse angle. This must be done very carefully, since the slightest scratch will reduce the electrical conductivity, and a large cut can even lead to failure of the entire wiring. It is highly not recommended to remove the insulation with wire cutters or pliers, as they deform the wire;
pre-twist the ends in a screw order;
insert the wires into the insulating cap;
turn the cap a couple of times clockwise.

The cap must be screwed in clockwise

Thus, the wires will be firmly and securely fixed inside the cap.

It is strongly recommended to test the caps before working use. To do this, it is necessary to connect two cables using PPE and test them with a load device for about half an hour at rated current. After that, it is necessary to analyze the level of heating of the contact, then increase the current level and identify possible problem areas.

It must be remembered that the twisting of aluminum wires must be carried out very carefully and accurately, since the metal itself has quite low temperature melting, so it can be deformed very easily.

Do not connect aluminum and copper wires together - the aluminum wire will quickly oxidize and the galvanic couple formed in this way 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;
PPE-2 - designed for three cores section 1.5 mm, color blue;
SIZ-3 - designed for two wires with a cross section of 2.5 mm, orange color;
SIZ-4 - designed for four cores with a cross section of 2.5 mm, yellow;
SIZ-5 - designed for eight wires with a cross section of 2.5 mm, red color.

However, it must be remembered that there are also European-made PPE. 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 the number of wires that are indicated on the package.

If you use a cap for twisting the wrong size and diameter, there is a high probability that it simply cannot be put on the wires, and when using PPE too big size it is possible that the cap will fly off and the entire electrical wiring will fail.

Comparison with analogues

The main analogue of PPE caps are screw terminal blocks. In this case, two wires are connected together with a screw. However, this method has several disadvantages:

the connecting screw must be tightened periodically, as 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 Chinese-made terminal blocks made of polyethylene sheath, which, if used, may cause a fire.

In contact with

When assembling electrical circuits, it is required to connect the wires to each other. An electrical contact is created at the connection point, which has a certain electrical resistance.

The task of any installer is to ensure a strong bonding of wiring with a minimum contact resistance and reliable electrical insulation.

For these purposes are used:

twists;
twists with welding;
soldering;
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.

Usually, two main methods are used for high-quality connection of two wires: twisting followed by soldering and ordinary twisting (without soldering).

But it is worth noting that despite the advantages traditional methods they are also endowed with some disadvantages: soldering, being a high-quality connection during disassembly, requires complete removal (“biting off” the soldered part of the wires), which is not always possible due to the stock of the wire, twisting increases the chance of oxidation and does not guarantee a reliable connection.

To date, there is another solution to such problems - these are connecting.

PPE caps for twisting wires

PPE caps- these are connecting insulating clips, which are made of non-combustible plastic compound. Inside these caps is a conical metal spring.

When they are twisted with little effort, the spring expands 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, inside of which there is a thread. 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 disassembled without the slightest problem.

Connecting caps are produced different sizes for wires from 0.5 to 1.6 mm in diameter.

As a rule, the color of the cap corresponds to a certain 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 characterized cross section total twisted wires. This section is expressed by the PPE number from 1 to 5. This figure characterizes the section and the number of strands twisted.

brand	Quantity and section of cores, mm²	Colour
PPE-1	2×1.5	grey
PPE-2	3×1.5	blue
PPE-3	2×2.5	Orange
PPE-4	4×2.5	yellow
PPE-5	8×2.5	red

Accordingly, the larger the number of the PPE cap, the larger the cross section and the number of wires it is intended for.

All wire connections assembled on self-clamping terminals or insulating caps have high efficiency are gaining popularity.

Express terminals allow you to quickly create reliable connection, but have more complex structure, somewhat more expensive. They are more often used to connect conductors to new measurement, automation and protection devices operating on microprocessor circuits.

For everyday frequent use, they are better suited with simple device. The connection of the conductors is achieved by screwing their metal ends into a strong spring, made in the form of a cone-shaped spiral.

It is not required to isolate the junction, 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 PPE wires

Installing the cap on the prepared wires is quick, does not require special tool. The created connection is compact. Caps are convenient to use. However, you need to know the rules for their application, develop the necessary skills. Inept handling can lead to sad 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 notation. Therefore, it is better to navigate overall dimensions for connecting wires, not the manufacturer's markings.

Use of PPE caps - practical application

Special care must be taken when handling aluminum conductors. Soft metal is easily deformed, quickly loses strength.

At cap twisting aluminum is reliably crimped by a conical spring and works well for a long time. Due to the occurrence of electrochemical processes, cannot be twisted together aluminum wires with copper.

It is important to remove the optimal length of the insulating layer from the conductor to ensure maximum area contact between metal parts. It's easy to define. It is enough to insert one wire inside the cap and visually mark the place of the insulation cut. Remove the insulation and repeat the control installation of the wire. Bare metal must not extend beyond the insulating part of the cap.

When removing insulation, use different ways. Many older fitters work with a fitter's knife with an insulated handle and a short, sharp blade made of strong steel. Often used wedge or razor sharpening, which removes insulation well, but in inexperienced hands can cause harm.

With a knife, especially when it is perpendicular to the conductor, it is possible to break the outer surface of the metal. Any, even an inconspicuous scratch, when twisted, will increase in size, reduce the cross section of the conductor, reduce it electrical characteristics. The metal will begin to warm up and burn out, especially under heavy loads. A deep cut in the conductor will cause the wire to break when twisted.

It is necessary to remove the insulation with a knife when its blade is located at an obtuse angle to the conductor relative to the direction of the cut with light movements without damaging the metal.

A certain part of electricians use pliers or wire cutters to remove insulation, deform the metal at the conductor crimp, which is not acceptable. You can qualitatively remove the insulation with special pliers produced for such work.

The method of twisting the wires with pliers and then putting on the cap does not provide reliable contact and its isolation. Caps just fall out over time. But some installers don't get it.

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 assess the effectiveness of the use of caps before their mass use, it is required to connect the wires with them and pass the load device through it with a current of a nominal value for about half an hour. Analyze connection heating. Then exceed the current and identify problem areas.

Such electrical tests help professionals to recognize the weak points of the electrical circuits they create, improve their skills, and perform quality work.

Currently, in many premises, and, regardless of whether it is an apartment, office or public building, there are many electrical work. For example, electrical wiring is being laid, some kind of lighting or technique. All of this work requires a constant connection of many different wires.

When connecting wires, many different reliable and safe ways e.g. with bolts or special terminals. But one of the most simple ways can be considered use to perform similar work, simply referred to as PPE. It is due to the ease and simplicity of its use as a connecting element that caps have become widespread and popular. PPE.

In addition, the reason for the extraordinary popularity PPE caps one more of their great advantages can be called - the safety of use during electrical work. In fact, the material from which they are made has excellent insulating properties and does not support combustion processes at all.

Inside PPE cap there is a spring, with the help of which the connection is made electrical wires. The cap itself is made of special plastic, which not only perfectly protects the junction from any mechanical influences on it and serves as an excellent insulator, but also prevents the spread of fire in case of fire hazardous situations.

On the modern market of electrical goods there is a huge range of connecting insulating caps. They differ from each other not only in size, shape, type or color, but also in denomination. It is indicated on the body of the PPE cap and is designed to give information about what wires with which cross-sectional area can be connected using this particular cap.

By purchasing PPE caps their denomination should be taken into account exactly and only used exactly following the indicated value. Therefore, only individual caps selected for them can be used to connect each specific wire. This is not surprising, because in the event that the PPE cap turns out to be of a lower value than required, then the connection simply cannot be made, the wires will not fit into the cap. Otherwise, if the cap is larger, then it will simply be useless when connecting electrical wires.

By purchasing connecting insulating caps it should be remembered that the nominal value of products manufactured in European countries is slightly lower than the corresponding indicator of their counterparts manufactured in our country. By the way, you should never forget that with the help of PPE caps should never be combined copper wire with aluminium.

When it comes to color PPE caps, which can be seen on sale, it can be noted that it means absolutely nothing. They are available in different colors just for the convenience of the consumer. Using when connecting electrical wires multi-colored PPE caps, with further operation of these compounds it will be easier to navigate in them.

Thus, having an idea of what the connecting insulating caps are intended for and always having them at hand, you can simply, quickly and efficiently make a safe connection of electrical wires.

From the point of view of current regulations, wire strands can be roughly divided into two types:

correct
not correct

The correct ones include those twists that are somehow fixed. The following can act as a fixer:

Wires that are simply twisted without fixation are considered not the correct connection element. At the same time, it doesn’t matter how many turns you have turned, how beautifully you connected the cores - all this is outside the rules and is prohibited.

Soldered and welded cores are considered the best connection, however, for the majority they are simply not suitable, due to the banal lack necessary tools or skills.

If you yourself decide to repair the wiring, assemble the junction box and at the same time save on installation, without violating the current rules, then PPE caps are ideal.

First, you do not need to buy any special tools. For example expensive welders or press tongs.

Secondly, you do not need to acquire any additional skills, as is the case with soldering or welding wires.

PPE caps - 8 types

PPE - stands for connecting insulating clamp. This type caps came to us from the West. In America, it is this connection and the method of insulating wires that is considered the most common.

Moreover, the choice of foreign consumers is much richer than ours.

Our manufacturers actually produce only two types of PPE:

In the West, as they say, you can pick up for all occasions. It is not clear why the Chinese have not yet made a fuss and have not begun to produce the same thing for our market.

Here are the main 8 types of PPE caps that you can find there (taken from here).

This is the classic and reinforced (with wings) PPE that we are all familiar with:

PPE with an improved cap shape that provides more comfortable work when twisting:

PPE cap with low profile design for working in confined spaces or small junction boxes:

Low profile design with winglets for increased torque:

The next cap is a very controversial decision in my opinion, but it is also produced. PPE for connecting aluminum conductors with copper. The cap is filled with a special antioxidant that prevents oxidation:

Moisture-proof clamps that can be installed on wires in electrical cabinets on the facade of the house, or wet rooms, and even directly in the ground in the garden:

They contain 100% silicone sealant which protects against moisture and corrosion.

There is no need for heat shrinkage or hermetic insulation of the joints.

PPE with a hole in the top of the cap.

This is not a defect at all, as it might seem at first glance, but a clamp specially designed for twisting grounding conductors. One of them is just brought out through the hole and connected to the body of the shield or equipment.

There are also similar clamps, where the wire is pressed not with a spring, but with a screw connection.

There is also a device - a connector filled with silicone.
Any PPE cap with wires is placed inside it.

After that, this twist can be safely considered waterproof and placed underground - in the garden, near watering cans, when entering the house, etc.

Sizes and selection of PPE caps

Domestic and Chinese manufacturers produce PPE caps in 5 sizes from PPE-1 to PPE-5. The largest of them is designed for a total cross-section of wires up to 32mm2.

By the way, be more careful when choosing caps based on the sections. Some Chinese PPE can put you in a stupor. On the cap itself, it can be written that it is designed for up to 20mm2.

And on the package from it - only up to 15mm2. What to believe is not clear.

Quality can be checked even by touch. Low-quality PPE is characterized by poor plastic, which can burst during use. You can tell it apart by simply squeezing it with your fingers.

More expensive and normal clamps, with difficulty, but are compressed under the force of two fingers. Not quality options coarser, and it is much more difficult to compress them.

Some, when twisting PPE, help themselves with pliers. Again, with cheap Chinese caps, with such work, a break may occur, or the spring may simply fall out.

A good PPE clip can easily withstand the operating temperature range from -40 to +105 degrees.

Here are the markings and types of PPE caps with all the characteristics that domestic manufacturer KWT:

The company also produces a reinforced version of the cap with ears or wings:

Caps with ears are, of course, much more convenient than simple ones, but here you need to proceed from the conditions free space in a distribution box. Since such ears can occupy up to 20% of the total area of the cap.

More PPE, as well as sleeve and fork tips can be distinguished by color. Each color corresponds to a specific wire section.

With the help of PPE, it is possible to connect 4,5,6 wires, the main thing is that the total cross-section of the twist corresponds to the calculated purpose of the PPE.

In this case, you can safely twist wires of different sections. When crimping wires with sleeves, this causes real problems and difficulties.

You can pick up and order sets of PPE caps for yourself.

How to properly twist PPE caps

Consider the process of twisting when using PPE. First of all, you need to accurately select the desired clamp according to the cross section of the wires. The quality of the connection will depend on this.

To do this, add up the total cross section of the conductors that will be twisted inside the cap.
Let's say it's 3 wires of 1.5mm2. This means that the total cross section of the twist is 4.5 mm2. Find the desired cap in the table.

In this case, it is not necessary to focus on extreme values so that the twist is not, which is called end-to-end. In this case, the clamp simply will not work, or it will work poorly, and the wires will heat up.

For our version of 4.5mm2, it is better to choose PPE-3, designed for twisting from 1.5 to 6mm2. PPE-2 in this case will not be the best choice.

1 way to twist PPE

First, combine the wires. There is no need to pre-twist or lay them on top of each other. Put them in a PPE cap.

After that, you begin to press inside the PPE, and turn the cap itself clockwise until the spring works. As soon as the spring has captured the cores, you can begin the process of twisting the wires.

If there is not enough hand effort, and the cap is without "ears", you can use pliers or even a screwdriver. The process will speed up at times.

There is even a specially designed screwdriver attachment for quickly twisting wires with PPE. With this method, the cap remains completely undamaged.

You can, of course, adapt an ordinary "shurik" for twisting without any adapters, however, the outer insulating layer of the cap is scratched.

2 way of twisting PPE

The second method involves the preliminary twisting of the stripped cores with pliers or, again, with a screwdriver.

Then you cut the ends for evenness, and only then screw the clamp onto the twisted wires.

Which method to choose depends on the cross section of the connected conductors.

Just try to twist 4 GOST wires with a cross section of at least 2.5 mm2 with your hands and a cap. The load on the cap and the spiral will be such that if you do not carefully move it, you can break it.

But twisting two wires of 0.5 mm2 into PPE is not a big deal.

Stranding length

What should be the length of the twist? According to the manufacturers' recommendations, the twist should be equal to or slightly less than the length of the cap itself (10-12mm).

IEC data sheet for PPE caps -
Data sheet Navigator for PPE caps -

If you make it 3-4 cm long, at first glance this should not affect the quality of the connection and its resistance. However, there is one caveat here. Namely - the dependence on the number of twisted wires.

The more of them, the more desirable to increase the length of the twist.

If you twist five wires at the same time, to the depth of the PPE cap of only 1.5 cm, then you will never be able to create the same contact area of \u200b\u200bthese wires, which is obtained with a twist length twice as long.

So approach the matter thoughtfully. The main thing after that is to securely insulate the remaining bare part of the wire.

True, in this case, the connection is no longer correct to call PPE, since the cap itself no longer insulates the entire bare core.

In any case and at any length, this twist turns out to be quite reliable and, thanks to fixation with an insulated cap, the wires will no longer loosen during operation.

After that, it can again be safely used on other equipment or object.

Another common use of PPE is the legalization of twists in old junction boxes following the instructions of fire inspectors.

The caps themselves are made of PVC compound, which does not spread combustion. And this is one of the conditions fire safety requirements to the electrics.
You open the box, remove the electrical tape from the old twist and wind a new cap over the cores. True, counterclockwise twists can come across, so be careful.

The disadvantages of insulated PPE caps include that they are not suitable for stranded wires and are applicable only for monofilaments.

Also, manufacturers do not recommend twisting aluminum wires with them, indicating that this is primarily a clamp for copper.
Separate firms, as mentioned above, produce universal PPE clips designed for aluminum too. However, for the most part, their use for this particular metal is prohibited.

And sometimes it can lead to the following consequences:

Domestic PPE also does not provide a tight connection. In a damp room, moisture can accumulate inside the cap, which gradually leads to rust and a violation of the compressive force of the spring.

To avoid this, you can insulate both the wires and the PPE cap itself with electrical tape.

Another inconvenience of such clamps is their dimensions. If there are a lot of wires in the junction box, then the PPE will take up a lot of free space inside. Sometimes this can even force you to replace the box with another, larger one.

In general, insulated PPE caps are chosen primarily for their cost-effectiveness and ease of installation. If you need a more reliable and durable connection, then invite professional electricians with all the necessary equipment.

And here is a curious test of the PPE cap for mechanical stress. The guy collected the wires in PPE and hung a punching bag for him, thereby checking how mechanically reliable this contact can be: