- Twisting wires
- Soldering wires
- Terminal connections, wiring options
- Insulation of electrical connections
The article discusses the issue of making a reliable connection of two or more conductors using twisting, soldering and terminal connections. Variants of using these techniques are proposed for the reliable connection of two or more wires to various electrical appliances.
The simplest way to connect two or more conductors is the so-called twisting. This connection is performed using various techniques, of which simple twisting is intuitive..
Connecting two flexible, stranded wires in a simple parallel twist provides reliable contact between the two wires, but the twist does not tolerate vibration and tensile stress.
With the help of parallel twisting, it is possible to connect solid and stranded copper wire, due to the additional bending of the solid wire, this connection is more reliable than when connecting two stranded wires.
A similar method is used to connect aluminum wires of various cross-sections..
The use of parallel twisting makes it possible to provide electrical contact between two or more wires simultaneously.
With a simple twist, the additional wire can be electrically connected to the main wiring line without breaking it. To do this, in the right place, the insulation is removed from it, after which, using a simple twist, an additional conductor is connected.
This same connection method can be used to connect a monolithic wire outlet with a flexible or solid main wire together..
To connect two wires together, they can be twisted sequentially, for which each wire to be connected is “wound” onto the other.
This method of connecting wires allows for optimal contact and reliability of the connection, but only for two wires.
The connection of rigid wires to each other can be performed using bandage twisting. To do this, the wires to be connected are applied parallel to each other, after which they are fixed in this position using a softer wire that fits tightly on the bare surface of the wires.
The tighter the twisting or winding is done, the better the electrical contact between the conductors will be..
With the help of a band, you can make a connection of two or more conductors or organize branches.
To improve fixation, you can perform additional bending of the monolithic wire, thereby fixing the bandage.
During installation, it is necessary to ensure that the twisted parts of the conductors are completely cleaned of insulation, the copper or aluminum surface of the conductors must be clean and free of oxidation traces. If necessary, the surface of the wires to be connected must be cleaned with a knife or emery paper before twisting. To increase the twisting density, and, as a consequence, the electrical contact between the conductors, twisting is allowed using pliers. It is important to remember the main rule of installation – you cannot make a direct connection of copper and aluminum wiring.
With the help of special solder and an electric soldering iron, it is possible to provide a more reliable connection between all types of copper wiring. Coating the copper wire with a thin layer of lead-tin solder (tinning) protects it from oxidation under the influence of high humidity.
Depending on the composition and melting point, the following main types of solder are distinguished:
- POS 15 – 280 ° C.
- POS 25 – 260 ° C.
- POS 33 – 247 ° C.
- POS 40 – 235 ° C.
- POS 60 – 191 ° C.
- POS 61 – 183 ° C
- POS 90 – 220 ° C.
To connect, each conductor is tinned with rosin (flux) and solder:
- The conductor is stripped of insulation and possible oxidation.
- With a heated soldering iron, the wire is heated to the melting point of the rosin and dipped into it.
- Solder melt is collected on the tip of the soldering iron.
- With smooth movements along the conductor, the solder is transferred to the copper conductor.
After tinning, the conductors are connected to each other by means of one of the previously described twists. Before pulling the conductors into a twist, non-evaporated flux residues are removed from their surface with a knife. Since the stiffness of the tinned wire is much higher in comparison with the untreated one, the twist is “tightened up” with pliers. For a reliable electrical and mechanical connection of wires, the subsequent heating of the twist with a soldering iron is performed to the fusion temperature of the tinned surface of the conductors. For a reliable connection, additional application of solder may be required in the place of twisting of tinned wires.
Since copper conducts heat well from the soldering iron, severe overheating of the conductor can cause the wire insulation to melt; to minimize this negative factor, the most optimal solder melting temperature is selected and the conductor heating time is reduced.
Terminal connections, wiring options
Today, a large number of various terminal connections have been developed, allowing you to securely fix the wires and ensure high-quality electrical contact. The conductive surface of the terminal blocks is made of brass or other materials that do not interact with either copper or aluminum, so they can be used to organize a copper-aluminum transition.
Most terminal blocks can be divided into two types.
1. Presser. In this terminal block, the wire is fixed using a built-in spring.
2. Screw. Here, the wire is fixed with a screw.
In our case, to increase the contact area of wires with a conductive surface made of brass, copper and aluminum wires are additionally bent.
When using screw terminal blocks, it is important to remember that copper and aluminum are very soft materials, and excessive force when tightening the terminal connection can lead to both “breaking” the thread and squeezing the wire.
For thin flexible wires, special ferrules are recommended.
If necessary, the terminal block can be replaced with a metal bolt with a small number of washers and a nut.
To securely connect a stranded or solid copper wire to aluminum wires, a steel or brass washer is placed between each conductor. The wires are pre-stripped and bent with a “ring”. The wires are laid on the bolt so that when the nut is tightened, the “ring” does not unbend. The bolt used for wiring must be clean, not rusty, galvanized and stainless steel bolts work best.
To connect more than one wire to the terminal at the same time, it is recommended to first connect them using the previously discussed types of parallel twisting.
Such installation will optimize the electrical contact and eliminate the possibility of poor pressing of the wires..
Insulation of electrical connections
All parts of the wiring must be insulated to prevent accidental contact of parts of conductive elements with each other and with the human body. The choice of insulating materials depends on the operating conditions of the electrical circuit. For most applications, heat shrink tubing or vinyl tubing insulation and special insulating tape are sufficient..
If the junction can be exposed to high temperatures, then varnish cloth and fabric insulating tape are used for insulation, which can withstand prolonged exposure to temperatures up to 100 ° C.
The operation of electrical wiring depends on many factors, among which not the least is the correct electrical installation. Reliable connection of wires and correct connection of elements of the electrical network allow you to avoid the occurrence of places with poor contact and, as a result, local overheating and breaks in electrical wiring.
The wire connection method used depends largely on the maximum load and operating conditions of the wiring. In damp rooms and outdoors, copper wiring with soldered connections should be preferred, as it is less sensitive to oxidation.