The situation where you need to combine three wires into a single electrical circuit is one of the most common tasks in electrical installation. This may be required when installing a new outlet, connecting a chandelier or repairing the wiring in the car. The quality of the connection directly affects the safety of the entire system.
Incorrectly executed docking of the currenters of the veins often causes overheating of contacts, melting of insulation and even a fire. Electric current, passing through the contact point, meets resistance, and if the connection is made carelessly, this resistance increases, causing local heating. That is why it is important to choose the right method and strictly follow the technology of work.
In this article, we will discuss in detail the main ways of connection, from classical twisting to modern spring-plate. You will learn what tools will be required for the job, why you can not just twist copper with aluminum and how to protect the joint from moisture and oxidation. Competent approach to installation will ensure the durability of wiring and peace of mind for the result.
Choosing the connection method and preparing tools
Before proceeding to twisting or soldering, it is necessary to decide on the method of fixation. The choice depends on the material of the veins (copper or aluminum), the cross-section of the wires and operating conditions. For household networks, copper cables with a cross section of 1.5 or 2.5 mm2 are most often used, for which almost all methods are suitable. However, when it comes to connecting three wires of different cross-sections or materials, the requirements for the method become stricter.
The most important stage is the preparation of the veins. The insulation shall be removed to a length which allows for reliable contact, but shall not leave bare areas outside the connector. It is best to use a specialized stripperwhich does not damage the vein itself. If there is no stripper, you can use a bokores or a knife, but you need to act extremely carefully so as not to make notches on metal.
For quality work, you will need a set of tools that should be at hand for every home craftsman. The lack of necessary equipment often leads to "kolkhoz" execution, which is unacceptable in electricians. The core set includes:
- 🔧 Passenger or pliers for twisting the veins and fixing the elements.
- ✂️ Scorchers for cutting the extra length of the wire and insulation.
- 🔥 Construction hair dryer or a heat shrink lighter (if no tape is used).
- 🧤 Dielectric gloves Protect your hands when accidentally touching the live parts.
Special attention should be paid to insulation materials. Depending on the chosen method of connection, you may need high-quality polyvinyl chloride insulation or shrink tubes. Using cheap materials can cause the insulation to dry out or slide after a short time, leaving the connection vulnerable.
⚠️ Attention! Before starting any work with electrical wiring, be sure to disconnect the network. Turn off the automatic switch in the shield and check for no voltage with an indicator screwdriver or multimeter.
The method of twisting: when it is permissible and how to improve it
Wire coiling is the oldest and most controversial method of connection. It provides excellent electrical contact if done correctly. On the other hand, modern rules of PPE (Rules of the Device of Electrical Installations) prohibit the use of twisting in its pure form as a final. This is because over time, the metal can “flow”, the contact weakens, and oxidation increases.
However, twisting remains an indispensable preparatory step for other methods, such as soldering or welding. To perform high-quality twisting of three wires, it is necessary to fold them in parallel and tightly twist the passages. It is important that the turns lie flat, without gaps. If the twist is loose, it will warm up even at the nominal load.
Additional treatment is often used to improve contact and protect against oxidation. After twisting, the connection can be soldered or pressed. In cars where vibration is a constant factor, a simple twist will quickly disperse, so there its use without additional fixation is strongly discouraged.
There are several twisting techniques that provide different reliability. For the connection of three wires, the method of "bandage" is optimally suited, when an additional wire is wound over the main connection, or serial twisting. The main rule is to ensure the maximum contact area lived.
Why is copper and aluminum rolling dangerous?
A galvanic pair of copper-aluminum in the presence of moisture forms a weak current that destroys the connection. Aluminum oxidizes faster, contact deteriorates, heat and sparking begin.
Salting and welding: creating an inseparable connection
If maximum reliability is required, especially in conditions of high humidity or vibration, soldering is the best choice. This method turns three separate conductors into a single monolithic element. For brazing copper solder POS-60 or similar alloys, as well as flux (canifole or soldering acid).
The soldering process requires preliminary cleaning of lived to shine and their serpent. The stain is a thin layer of stained steel. Only then can you tie three wires together. The heated soldering iron should evenly warm the connection so that the solder runs into all the voids between the veins. If the solder just lies on top of the lump, there will be no quality connection.
Wire welding is an even more reliable, but complex method that requires special equipment. At the point of contact, a high temperature is created, and the ends of the wires are melted, forming a characteristic ball. This method is often used in industrial electrical installation. At home for one-time work, a welding machine for wires is unprofitable to buy, it is easier to use soldering or terminals.
☑️ Algorithm of quality soldering
After soldering is completed, flux residues must be carefully removed, as the active acids can break down the insulation or cause metal corrosion over time. The cooled connection must be stationary. Any attempt to bend the soldered wire at the joint immediately after cooling can lead to microcracks.
Climax pads and spring clamps
Modern electrical engineering offers many solutions that eliminate the need to twist and solder wires. Clutch connections are the fastest and most convenient way to connect three wires. They are divided into screw and spring. Screws require periodic lifts, as the screw may weaken from vibration or temperature expansions.
Spring terminals, such as firm products WagoIt is considered one of the most convenient solutions for home installation. Inside such a clamping is a special paste that protects the contact from oxidation, and a spring that provides constant pressure on the vein. To connect three wires, it is enough to clean them for the specified length and insert them into the holes to the end.
However, spring terminals have their limitations. They are usually designed for a certain amount of current. If you are connecting a powerful consumer, such as an electric stove or heater, you need to make sure that the terminal will withstand such a load. For power lines, it is better to use screw terminals with a plastic case or brass shells.
| Type of connection | Reliability | Difficulty of installation | Need for maintenance |
|---|---|---|---|
| Scrub (no ration) | Low. | Low. | High (must be pulled) |
| Pike. | Tall. | Medium | Absent. |
| Spring terminals | Medium/High | Very low. | Absent. |
| Sleeve-pressing | Very high. | High (tool needed) | Absent. |
When using terminals, it is important to prevent insulation from entering the clamping inside. Contact should only be between the metal of the wire and the terminal contact platform. If the insulation falls under the screw or spring, the contact resistance will increase, which will lead to heating.
Restraining: Professional approach
Pressing is one of the most reliable ways of connection, which is allowed by the rules of the PPE and is widely used in professional installation. The essence of the method is that the cleaned ends of the three wires are inserted into a special metal tube - a sleeve, which is then squeezed with a special tool - crimper.
The shells are copper, tinted and aluminum. It is important to select the material of the sleeve in accordance with the material of the wires. For the connection of copper wires, GM or GML (lean) sleeves are used. Aluminum GA shells are designed for aluminum. If it is necessary to combine copper and aluminum, use combined shells or shells with a partition.
The process of squeezing requires precision. You can not squeeze the sleeve with ordinary passages, since it is impossible to ensure a uniform force in a circle. An uncrushed sleeve will have poor contact, and a clamped one can damage the veins. Professional mites have profiled sponges that form the correct bending of the metal, ensuring a tight fit.
For pressing three wires, use a sleeve with a margin of internal diameter so that all veins enter freely, but without excessive backlash. After inserting the wires, slightly tap the sleeve on the table so that they lie down tighter.
After pressing, the ends of the sleeve should be insulated with thermal shrinkage or seal, although some types of sleeves already have an insulating layer. This method is ideal for distribution boxes where compact and perpetual connection is required, which does not require maintenance for years.
Connection of wires of different cross-section and material
Often there is a situation when you need to connect three wires that differ in cross-section or material. For example, a thick cable goes from the shield, and from it you need to power several lines with thin wires. In this case, a simple twist is strictly prohibited, since a thin wire may not withstand the current that will freely pass through the thick, or the contact will be unstable due to different stiffness of the veins.
The best solution for such cases is terminal pads or special transition sleeves. In the screw terminal, you can pinch wires of different diameters, the main thing is to make sure that the screw securely presses both conductors. If one wire is significantly thinner, it can be folded in half before inserting into the terminal, but only if the clamp design allows it.
The combination of copper and aluminum is a separate topic that requires special care. As mentioned earlier, direct contact of these metals leads to electrochemical corrosion. The following shall be used to combine them:
- 🔩 Bolt connection The stains are made of steel, and the stains are made of steel.
- 🛡️ Clemmn with a paste that prevents oxidation.
- 🔌 Combined shellswhere one side is for copper and the other for aluminum.
⚠️ Attention! Never twist copper and aluminum wires directly. This is guaranteed to lead to contact oxidation, heating and possible fire after a while.
When working with different sections, it is important to take into account the current load. The connection must withstand the current that consumes the most powerful appliance in the circuit. If you connect a wire of 4 mm2 and two wires of 1.5 mm2, the total current should not exceed the permissible for the thinnest section.
Isolation and final inspection of work
Once the connection is made, it must be qualitatively isolated. Even if you used a terminal with a body, it is better to additionally protect the node in the junction box. For insulation of twists and soldering, a shrink tube is ideal. It tightly fits the connection, creating a sealed cocoon, resistant to moisture and mechanical stress.
If the insulation is used, it should be wound in several layers, starting with the whole insulation of the wire and switching to the connection, with a cover of at least 50%. In automotive wiring, fabric isolating is often used, which is more resistant to high temperatures of the under-hood space than conventional PVC.
The final stage is the test. Before applying the voltage, visually make sure that there are no protruding veins, and the connection looks neat. If possible, "click" the chain multimeter for short circuit. The resistance between phase and zero should be infinite (if the load is turned off), and the resistance of the connection itself should tend to zero.
Quality insulation is as important as the contact itself. Poor insulation can lead to short circuits even when twisted or soldered perfectly.
Power is best turned on under supervision, by controlling the connection (if it is open and safe to observe) or simply by listening to the absence of cod and the smell of burning. In the first minutes of the new chain, it is recommended to periodically check the temperature of the connection site with your hand (carefully) or a thermal imager.
Frequently Asked Questions (FAQ)
Can you connect three wires with a simple twist without soldering?
According to modern rules of PUE, twisting as an independent method of connection is prohibited, since it tends to weaken with time. The cloth must be either soldered, or pressed with a sleeve, or used over it with a terminal. Temporary connection twisting is permissible only for a short period of time.
What if the wires are too short to connect?
If the length of the wires is not enough, they can be increased. To do this, the same method of connection (stem, soldering) is used, but the place of the joint is necessarily hidden in a distribution box or a rosette. Hide the connection simply in the wall under the plaster is prohibited - it must be accessed for maintenance.
Which conductor is best used for grounding in the connection of three wires?
For grounding, be sure to use a wire with yellow-green insulation. Its cross-section shall not be less than the section of the phase wire in the circuit. The connection of ground conductors should be particularly reliable, as the safety of people depends on it. It is best to use a pressing or quality terminals.
Do I need to change the insulation on the entire wire if only the section at the twisting is damaged?
No, you don't have to change the whole wire. It is enough to clean the damaged area, make a connection and qualitatively isolate the joint with a thermal shrinkage or tape. The main thing is to ensure the tightness and mechanical strength of the insulation.