High-quality connection of conductive wires is the foundation of safe operation of any electrical network. Copper wire terminals for crimping wires They are a key element that provides reliable contact and protection against overheating. Unlike soldering or twisting, mechanical clamping using a specialized tool creates a monolithic structure that is resistant to vibration and oxidation.
Automotive wiring and stationary power supply systems are subject to constant dynamic loads. That is why the application TM-heads or tubular clamps becomes not just a recommendation, but a technical requirement. Incorrectly selected section or violation of installation technology can lead to a voltage drop and even fire.
In this article we will analyze in detail the types of copper connectors, the features of their marking and the critical nuances of working with them. You will learn how to choose the right tool and avoid the common mistakes that even experienced electricians make when forming contact groups.
Advantages of scaling before rationing and twisting
Wire coiling, despite its popularity in the past, is now recognized as an unreliable method of connection. Over time, copper under the influence of oxygen is coated with an oxide film, which increases the transient resistance. Pressure eliminates this risk, as the metal deforms under high pressure, eliminating the air gaps between the terminal and the residential.
Salting, in turn, requires an open fire or a powerful heating element, which is not always convenient, especially in the conditions of a close engine compartment of the car. In addition, solder has a higher resistance than pure copper, and at high currents can "swim". Use of the crimp-head It allows you to maintain the natural electrical conductivity of the material.
⚠️ Note: Vibration is the main enemy of electrical contact. Solder joints in the cold become fragile and can crack, while properly compressed copper terminal works as a unit with the wire.
The mechanical strength of the connection depends on the quality of the tool and compliance with the technology. Modern. clipper provide sufficient force to create metal diffusion at the molecular level. This ensures the stability of the chain parameters throughout the life of the product.
Classification of copper connecting elements
The market of electrical products offers a wide range of products for switching. The main division occurs by type of design and purpose. Tubular tips (often called sleeves) are designed to connect the ends of wires together or create a loop under the bolt. They are made of a solid-stretched copper pipe and often have a tinted coating to protect against corrosion.
To connect to the terminals or tires are used hub-head (NSHVI) Their design involves installation on a multiwire vein, preventing its dissipation when tightened by a screw. This is especially true for automotive acoustics and alarm systems, where contact density is important.
A separate category is made up of insulated terminals, where the copper part is covered with PVC or a nylon shell. The color of the insulation usually corresponds to the wire cross section, which simplifies visual control. However, for power chains under the hood of the car, it is preferable to use copper-element with subsequent shrinkage, since the plastic may not withstand the temperature regime of the engine.
- 🔌 Ring terminals have a closed hole that prevents the wire from slipping when the bolt is weakened.
- 🔌 Fork (carob) terminals - allow you to establish a connection without full twisting of the fastening bolt, convenient for maintenance.
- 🔌 Prickheads - are used to connect to flat contacts of relays and fuses.
Marking and selection of cross-section according to GOST
Choosing the right size of the terminal is the key to success. The main parameter is the cross-section of the wire for which the tip is intended. On products of domestic production and quality imports there is always a marking. For example, a designation TM 50-8-10 It stands for: copper tube tip for a wire 50 mm2, with a hole under the bolt 8 mm, a blade width of 10 mm.
Ignoring the correspondence of the section leads to deplorable results. If you take a smaller terminal, the conductor may not enter completely or deform, which will reduce its throughput. Too large a sleeve will not provide the necessary pressure, and the contact will warm up.
Table of correspondence of insulation colors and cross-sections
For sleeve tips (NSHVI) adopted standard color coding: white – 0.5 mm2, gray – 0.75 mm2, red – 1.0 mm2, blue – 1.5 mm2, yellow – 2.5 mm2, black – 6.0 mm2. Knowledge of these colors allows you to quickly identify the size without using a barbell.
When working with multiwire veins, it is important to take into account the total cross section of all hairs. Stuff density It should be maximum. If the wire dangles inside the sleeve before pressing, the connection will not be sealed and durable.
| Marking | Wire cross-section (mm2) | Hole diameter (mm) | Color of insulation (if any) |
|---|---|---|---|
| NSHVI 1.5-8 | 1,5 | 8 (length of shell case) | Blue |
| NSHVI 2.5-8 | 2,5 | 8 (length of shell case) | Yellow |
| TM 16-6 | 16 | 6 | No (copper/serling) |
| TM 25-8 | 25 | 8 | No (copper/serling) |
Tool for professional installation
The quality of the connection depends on the tool used by 80%. Conventional pliers or passages are not able to provide uniform compression from all sides. For copper terminals Specialized crimperes (crushing ticks) should be used. They have profile sponges that form the correct bending of the metal.
There are mechanical and hydraulic tools. For automotive work and home electricians, high-quality mechanical mites with a rattling mechanism are usually enough. A rattle does not allow to unclog the sponges until the completion of a full compression cycle, which excludes the human factor and is ineffective.
☑️ Checking the readiness for pressurization
For power cables of large cross-section (from 35 mm2 and above), hydraulic presses are used. They create a force of several tons, necessary for plastic deformation of thick copper. In the garage for such work often use removable matrices installed in a hydraulic jack or a special hand pump.
It is important to monitor the condition of the tool sponges. Dulled edges can "cut" the wire or leave burrs, which in the future will become foci of corrosion or breakdown of insulation.
The technology of correct pressing
The installation process requires compliance with the sequence of actions. First, the insulation is removed from the wire. The length of the stripping shall correspond exactly to the length of the tubular part of the terminal. If you clean too much, the bare part will protrude, creating the risk of short circuit. If not enough, the contact will be poor quality.
The cleaned copper vein must be treated. For multiwire wires, it is recommended to twist them slightly with your fingers to give a round shape, but not overdo it so as not to damage the thin hairs. Then the wire is inserted into copper-sleeved All the way.
⚠️ Warning: Never use a hammer or a manual to clench. Such a “grandfather” method deforms the veins, violates their structure and does not guarantee the tightness of the connection, which is unacceptable in the car due to vibrations.
The instrument shall be mounted on the terminal perpendicular to the axis of the wire. Compression is made smoothly, until the mechanism is triggered (if there is a rattle) or before the sponges close. For long tubular tips, two or three overlapping clamps are often made along the entire length, moving from edge to center.
Use a heat shrink tube with a glue layer over the finished connection. This will protect copper from moisture and oxidation, and will also add mechanical strength to the joint site.
Common Errors and How to Resolve Them
One of the most common mistakes is the use of aluminum tips for copper wires and vice versa. galvanic pair Aluminum copper is rapidly oxidized, resistance is growing, heating begins. If you need to connect different metals, use bimetallic adapters or special lubricants.
Another problem is "unaffordable." Visually, the connection may seem strong, but an air cushion remains inside. You can check this by trying to turn the terminal on the wire with your hands. Luft is unacceptable. It is also dangerous to clamping, when the walls of the sleeve collapse completely, snacking part of the veins.
- ❌ Use is not in size (too large shell).
- ❌ Only one point instead of two or three.
- ❌ Attempt to squeeze the wire together with the insulation (for uninsulated terminals).
To eliminate the marriage, the connection must be remade. Cut the old terminal, clean the wire again (removing the damaged area) and install a new one tip. Saving on consumables in the electrician means risking safety.
High-quality pressing turns a set of wires and terminals into a single monolithic system capable of withstanding current loads specified in the specification without overheating.
Frequently Asked Questions (FAQ)
Can you squeeze a copper terminal with ordinary pliers?
Technically, you can compress metal, but such a connection will not be reliable. Flatheads do not provide uniform pressure on all sides (square or hexagonal crimping), which is necessary for close contact. Vibration quickly shakes such a design.
Do I need to squirt the wire before inserting it into the crimping terminal?
No, you can't lick the wire before the pressing. The solder under the pressure of ticks "float", the contact will weaken, and there will be a void at the connection site. The crimping is performed only on pure copper. The already finished connection is subjected to grazing, if it is required by the specifics of operation, but it is better to use tin terminals.
How to choose the color of an isolated terminal?
Color depends on the cross-section of the wire. Red - for 0.5-1.5 mm2, blue - for 1.5-2.5 mm2, yellow - for 4.0-6.0 mm2. Always check the labeling on the packaging, as the standards may vary slightly from one manufacturer to another.
What to do if the wire is multiwire and thin?
For thin multiwire veins, sleeve tips (NSHVI) are ideally suited. They assemble the beam into a monolithic cylinder, which is then easily and reliably clamped in a terminal pad or screw joint.