Melted cases of junction boxes, burnt wires, violation of the integrity of the cores are the consequences of neglecting such a procedure as cable termination. Without creating reliable contact with the device, you cannot be sure of the safety of the wiring. With the help of termination, it is possible to reduce the contact resistance, which causes melting of the contacts, to increase the reliability of the connection and to increase its operating time. Wiring termination methods are different, each of which has its own positive and negative sides.
Why is the absence of termination dangerous?
Termination is understood as the process of processing and shaping the core to create a strong connection with the device. When choosing methods for terminating wires and cables, it is important to understand how this or that material will behave and what needs to be done to make the contact strong. The most important condition for the safety of the electrical network is the creation of reliable and high-quality contact between the conductor and the device to which it is connected. If the connection is poor, a short circuit or fire may result. Loose contact results in high contact resistance. It is essentially a resistor that generates heat. The increased heat causes the wire to burn and melt.
It is necessary to get rid of the transient resistance. But this is a rather difficult task, which is interfered with by an oxide film, a small contact area, weak compression at the terminals of the switching device. You can only reduce the PS - in this case, the termination of the wire cores helps.
Termination methods
There are electrical installation rules (PUE), which regulate the work with electromechanical equipment. For these requirements, the master must know the following:
- Termination can be done by crimping, soldering, welding, special ferrules and fittings for wires, sleeves.
- The best method for terminating aluminum with a cross-sectional area of 2.5 mm2 to 10 mm2 is to bend the end of the conductor into a ring.
- Aluminum conductors with a large cross-section are terminated with crimped or welded lugs (for a cross-section from 240 sq. Mm.).
- The aluminum wire must be lubricated with a special grease at the termination point so that there is no contact with air. Otherwise, oxidation will form, leading to destruction of the conductor and contact.
- Copper wires up to 10 sq. Mm. bend into a ring, but first you need to solder them. Looping the wires will help create good contact and keep the wires from catching fire.
The most popular way to create endings is with a variety of tips. They are of different types, differ in material, purpose, size, characteristics, class.
Wire preparation technology
Termination can be done independently with a special tool. The technology is simple - just take the tip, put it all the way on the conductor and squeeze it. The number of clamps can be different - crimping of a matrix with a point contact is carried out in two or more places, and one crimp is enough for sleeves. Several pressings are necessary for a more reliable contact, a decrease in contact resistance and an increase in mechanical strength.
Crimping by professional craftsmen is carried out using an expensive special tool. It is not profitable for a home specialist to buy such a device, so they choose other options. Alternatively, a stripper with a press or a crimper (special crimp) can be used. All devices can be purchased at a regular hardware or electrical store.
There are solder tips. Then the termination is carried out in two stages - the stripped core is placed in the tip and solder is poured into the hole. This is a more reliable and high-quality method that is often used in electrical wiring.
Types of handpieces
You can quickly terminate a cable or wire using special ferrules. Their assortment is diverse - there are lugs for aluminum and copper wiring, for solid and stranded conductors. Each product has its own GOST marking, by which one can understand the purpose and characteristics of the electrical device, as well as the climatic conditions of operation.
Tips for copper wires TTM and TML
Stranded copper conductors can be terminated with special lugs made of copper pipe drilled for a bolt. There are two modifications of such devices - uncoated and tinned. They are also marked as TM (TML), after which the cross-section of the wire under the clamp is put in millimeters and the diameter of the tip hole in mm. The fastening of such clamps is carried out by crimping using special pliers. It is not recommended to use ordinary pliers or a hammer, otherwise the mechanism may be damaged. The number of crimps should be two or more for reliable installation.
Such lugs can also be used for single-wire conductors. It is only important to choose the right size, since otherwise the vein may break off. Before installation, the ends are cleaned from the insulating layer and oxide to a characteristic metallic luster.
The scope of such products is wide enough. They can be found in the connection of cable risers at the distribution input device at the entrance, in the grounding of metal junction boxes, in the connection of electric stoves, in the branch. They are also actively used in industry.
Suitable for termination are wires and cords with a cross section from 2.5 sq. Mm to 240 sq. Mm.
TML tips are best used in joints that must have high corrosion resistance.
TML (o)
A less used modification of TML ferrules is a crimping device with an inspection window that allows the technician to see the process of placing the conductor in place.
Such products are also mounted by soldering. Application area - industry. In everyday life, they are practically not used, therefore many home electricians and specialists in the field of housing and communal services do not even have an idea about the existence of such devices.
THERE
TAM aluminum and copper lugs for cables are used in connecting aluminum wiring to copper busbars on input and distribution devices. The product is a tip made of two metals, in which the shank is made of aluminum, and the body itself is made of copper. There is no transient resistance due to frictional diffusion. Installation method - crimping.
TA
Used for aluminum wires. Outwardly they are similar to products of the TM brand, but made of a different material. They have a minimum size of 16 sq. Mm.
The connection and termination of the conductors of wires and cables made of aluminum can be done only with the use of quartz-vaseline grease, which prevents the formation of oxide on the surface. Thanks to it, contact with air is reduced.
Other types of handpieces
Copper wires in household appliances are often terminated with copper lugs for soldering. The devices have special "ears" that allow you to securely fix the conductor.These products include the PM brand, in which the "ears" are brought together in production. They are used for wires with a cross section of 2.5 sq. Mm.
Reducing the size of switching devices, protective equipment led to a change in the size of the clamps. For this reason, pin-type NSHP wire terminator is increasingly used.
In the industry, cable bolted and mechanical lugs NB are actively used. With their help, power cables with a cross-section from 25 sq. Mm to 240 sq. Mm are terminated. They are made of aluminum alloy and have good corrosion resistance. To create tightness, a heat shrink tube is included in the kit.
The range of tips is very diverse, you can always find a device for this type of conductor, but many use homemade ones. Such products have an important advantage - the ability to create a tip for any size. They can be made quite simply - you need a tube made of the right material, flattened at one end, and then a hole is drilled into it. Self-made devices are used in grounding devices.
In the case of a self-made product, the current load is unknown. For this reason, it is not recommended to use them in industry and at high capacities.
