How to connect a 6 square cable to each other: professional methods

A high-quality connection of an electrical cable with a cross-section of 6 mm² is a critical step when installing power lines, whether it is entering the house, connecting an electric stove or a powerful machine in the garage. It is in this section of the circuit that problems most often arise if inappropriate switching methods are used or the technology is broken. Simple twisting is categorically unacceptable here, since the currents passing through a conductor of such thickness can melt the insulation in a matter of minutes if the contact is poor.

You need to understand that copper is a ductile metal, but under load it tends to “flow”, weakening the contact in threaded connections. Therefore, for the section 6 squares There are strictly regulated methods for creating permanent or serviceable connections. The correct choice of method depends on the core material (copper or aluminum), operating conditions and available equipment.

Errors in switching power lines lead not just to a power outage, but to local overheating, which can cause a fire. In this article we will analyze time-tested and PUE standards methods that guarantee the safety of your wiring for many years. We will look at the nuances of working with copper and aluminum conductors, since the physics of their connection is radically different.

Selection of materials and tools for quality installation

Before starting work, it is necessary to prepare a specialized tool, since an ordinary household knife or pliers may not be able to cope with a rigid conductor cross-section of 6 mm². For high-quality stripping of insulation, it is best to use a stripper with an adjustable blade or a sharp mounting knife, which must be used with extreme caution so as not to damage the core itself. Damage to even one wire in a multi-core cable reduces its throughput and creates a local heating point.

To create a reliable contact, you will need special consumables that match the wire cross-section. Using elements designed for a lower current will lead to their burnout. The main materials are tinned copper sleeves, terminal blocks with a pressure plate or special lugs for crimping.

⚠️ Attention! Never use ordinary plastic terminal blocks with screw terminals (“chandeliers”) intended for lighting to connect 6 mm² cables. Under high load, the screw will turn or the plastic will melt.

The key tool for professional installation is the crimper. If you plan to make a connection by crimping, then ordinary pliers will not provide the necessary force to deform the metal of the sleeve. There are manual models for home use and hydraulic ones for large volumes of work.

• 🛠️ Stripper or knife for removing insulation without damaging the core.
• 🔧 Press pliers (crimper) of the appropriate matrix size.
• ⚡ GML sleeves or NShV/NSHVI tips (for multicore).
• 🌡️ Hairdryer or burner for shrinking heat shrink tube.

Crimping method: the most reliable connection method

Sleeve crimping is considered one of the most reliable connection methods, which provides mechanical strength and excellent electrical contact. The essence of the method is to place the stripped ends of the cable inside a metal tube (sleeve) and severely deform it with a special tool. For a 6 mm² cable, GML sleeves (tinned copper sleeve) are ideal, which prevent oxidation of copper.

The process begins with a thorough stripping of the insulation. The length of the area to be stripped must exactly match the length of the sleeve or be slightly shorter so that the insulation does not get inside. If you connect two wires end to end, they are inserted from different sides until they meet in the middle. If it is necessary to extend the cable, a sleeve with a partition or a regular one is used, but with overlapping cores, which is less desirable for high currents.

After inserting the cores into the sleeve, crimping is performed. It is important to use the matrix strictly to the size of 6 mm². Insufficient crimping will not give the desired contact, and excessive crimping can damage the conductors or the sleeve itself. For a cross-section of 6 squares, double crimping is often required: first closer to the center, then at the edge to prevent the wire from coming out.

The finished connection must be insulated. The best solution is heat-shrink tubing with an adhesive layer, which, when heated, tightly fits the connection and seals it. This protects the contact from moisture and oxidation, which is especially important for garages or street panels.

Connection of copper and aluminum wires

The situation when it is necessary to connect a copper cable with an aluminum cable occurs often, especially when upgrading old wiring. Direct contact of these two metals is prohibited, since in the presence of moisture a galvanic couple occurs between them, leading to the rapid destruction of aluminum and heating of the contact. For such cases, there are special transition solutions.

One of the proven methods is the use of bimetallic sleeves GAM (aluminum-copper sleeve). One part of such a sleeve is made of aluminum, the other is made of copper, and they are connected by friction welding inside the product. You simply insert the aluminum wire into the aluminum part, and the copper wire into the copper part, and perform a crimp.

An alternative is bolted connections using washers or special terminal clamps filled with quartz-vaseline paste. The paste blocks the access of oxygen and moisture, preventing oxidation. When using the bolt method, it is important to remember about the locking washer, which compensates for the weakening of the contact over time.

Using Terminal Terminals and Blocks

It is not always possible or desirable to use crimping, especially if the connection needs to be disassembled periodically. In such cases, modern terminal clamps come to the rescue. For a cross section of 6 mm², ordinary “VAG” terminals of the 773 series (for monocore) can be used, but it is better to use more powerful series, for example, Wago 221 (lever) or 222, which have a transparent body for visual inspection.

It is important to distinguish between the types of terminals: some are suitable for monolithic conductors, others are suitable for stranded conductors, or they require preliminary crimping of the stranded wire with an NShVI tip. If you insert a 6 mm² soft stranded wire into a solid wire terminal without a ferrule, some of the thin wires may be crushed or not make contact, resulting in sparking.

For power lines, screw terminal blocks in a carbolite housing are also popular (for example, KBP). They allow you to connect wires of different diameters and materials if you use an intermediate steel plate or washers. When tightening the screws, you must use a torque screwdriver or be very careful not to overtighten the soft copper.

When installing in a distribution box, try to position the terminals so that they are easily accessible for inspection. Connections hidden in the wall, even high-quality ones, may require tightening of contacts over time, especially if screw terminals without spring compensators were used.

Welding and soldering: pros and cons for large sections

Strand welding provides perhaps the most ideal electrical contact, turning the joint into a monolithic piece of metal. However, for a 6mm² cable this method has its own difficulties. A powerful welding inverter (at least 300-400 Amps) and a special carbon electrode are required. The process requires skill: you need to melt the ends of the twist, but not burn the wire itself above the contact zone.

Soldering for such a section is also difficult. It is almost impossible to heat a strand of thick wires with a soldering iron; you need to immerse yourself in a bath of solder or use a gas torch. In addition, the consumption of solder will be high, and the mechanical fracture strength of the soldered joint is inferior to crimping. During vibrations (for example, in a garage or workshop), the soldering area may crack.

⚠️ Attention! When using an open flame (torch) to solder or heat shrink, be extremely careful with the cable insulation. PVC melts and burns, releasing toxic substances.

If you do choose welding, be sure to use a graphite electrode and a copper twist clamp so that the current flows evenly. After cooling, the connection must be carefully insulated, since during welding the insulation often burns out at a considerable distance from the end of the conductors.

Common mistakes and safety precautions

The most common mistake is incomplete insertion of the core into the sleeve or terminal. If the insulation gets inside the contact zone, the resistance increases sharply. Always make a visual inspection: for sleeves with an opaque wall, you can make a mark on the wire with a marker at the required distance from the edge of the insulation.

Another mistake is using steel elements (bolts, washers) to connect copper wires in a damp environment without protection. The steel rusts and contact is broken. All metal parts must be tin-plated or non-ferrous.

Don't forget about the load. A 6 mm² cable can withstand currents of up to 40-50 Amps (depending on installation conditions). All connecting elements must be marked at least this value. Using 10A elements will lead to their immediate failure.

Before applying voltage, be sure to check the assembled circuit with a multimeter for short circuits and circuit integrity. “Ringing” takes seconds, but saves you from expensive repairs and dangerous situations.