In the process of organizing the electric line, modern and outdated cable connection methods are used. Twisting the wires is the easiest way to fix, but it is prohibited by the PUE. However, if you have knowledge of the correct operation, you can safely make a branch or additional fasteners. Such a connection will not lead to a short circuit in the future.
The danger of twisting
In paragraph 21 of Ch. 2.1. PUE twisting is not prescribed among the ways of connecting wires. The rules allow the use of welding, soldering, clamps. The danger of twisting electrical wires lies in the following points:
- increasing the transition resistance of the contacts with a weak tightening of the cores;
- weakening of the twisted portion, leading to heating;
- increase in current with weak contact;
- reflow of the insulating conductor protection;
- risks of short circuits, fires, electric shock.
Despite the regulatory prohibition, most masters resort to the method of twisting. This option is suitable for testing the operation of the line, performing a short-term network, for the repair period.
Use special terminal blocks to twist the wires.
Advantages and disadvantages
The plexus of conductors is not designed to connect powerful devices - kettles, washing machines, heaters, refrigerators, computers. Despite this, twisting has several advantages:
- quick organization process;
- when properly executed - durability;
- lack of need for special tools;
- creating alarm contacts;
- additional gain when using soldering technology;
- minimum expenses for consumables;
- the possibility of re-execution.
Among the disadvantages are:
- mandatory isolation of the twisted section;
- normal operation of the line only when connecting low-power consumers;
- inconvenience of performance;
- risks of fire wiring in case of violations of the algorithm;
- constant voltage drops and overload of the twisted section.
Plexus is advisable when operating equipment with weak power - fixtures, power adapters.
Varieties of twists
Correctly twisting the wires, you can get a reliable and dense area. Masters resort to various types of connections - safe and durable:
- Bandage - an additional is applied to two segments and braids around them. This creates additional reinforcement of the site.
- Groove - with parallel technology, one core remains stationary, and the second wraps around it. This type involves making 3-4 turns around the second with one cable. Then the first lays tightly parallel to the second and again 3-4 turns are made;
- parallel connection. Two conductors with insulation removed at the same level are stacked side by side. The tips intersect tightly and twist in any direction.
All types of twists can be used as temporary fasteners.
Wire twisting according to PUE
The rules of the installation of electrical installations say that for twisting you can use a segment of 3-6 cm. The standards allow the connection of multicore and single-core cables with stripping of ends by 4-8 cm. The multicore conductor must be laid on a single-core and screwed by 4 cm.
PUEs set the type of wire for the home line.The aluminum cable should be with a cross section of 2.5-4 mm2, copper - 1.5-2 mm2. The power cord VVG and PV is used only with a PVC sheath. A wire of ШВЛ and ШТБ type with a cross section of 0.5-0.75 mm2 - with insulation made of rubber or PVC.
The process of preparing veins for twisting
To twist the electrical wires, you will need to disconnect the network by turning off the input circuit breaker. Next you will need:
- choose a tool with insulated handles and gloves made of dielectric material;
- remove the insulation coating from the cores so that the metal part remains intact;
- to wet a napkin in any degreaser (white spirit, acetone, nail polish remover) and wipe the bare parts;
- With sandpaper, clean the area of the core so that it acquires a characteristic metallic luster.
Twisting can only begin after preparation.
Options for twisting stranded wires
A stranded wire is a metal core in the form of thin veins. Elements are intertwined, forming a lay with external insulation. Manufacturers can cover wiring with polyurethane, add nylon threads to improve strength. Protection complicates the process of removing the insulating layer.
Twisting insulated stranded wires is performed in several ways.
Parallel connection
The simplest option is when two stripped cores are laid cross-on-cross one on one. Twisting is allowed only section without insulation. Parallel twisting ensures reliable contacts, but is not protected against breaks with effort.
The technology is suitable for copper conductors - one monolithic and one stranded. Aluminum conductors with different cross sections are also allowed to be connected in parallel. In the case of a monolithic wire, it will be necessary to remove more insulation than from a multicore.
After twisting, a segment should remain, from which an additional bend is created in the direction of fixation. This technique enhances the strength of the connection.
In a parallel way, you can fix more than 2 wires.
Sequential Seam Type
You need to fasten the wires together so that each of them overlays the other:
- veins are cleared of an insulating covering;
- stripped elements are stacked on top of each other;
- twisting starts from the center so that one wire wraps around the second;
- the second contact is twisted in a similar manner.
Due to its minimum reliability, the connection is suitable for two cables.
Bandage twisting
The best way to mount a stranded wire:
- two types of wire are selected - hard for fixing and soft for winding;
- insulation is removed from the cores so that the length of the exposed sections is the same;
- conductors are laid in parallel;
- To fix the cores between themselves, a third stripped wire is used.
As twisted products, you need to choose more than 2 rigid cables. The winding is organized using a flexible soft wire.
Features of twisting single-core wires
To twist single-core wires tightly and correctly, a parallel connection is suitable. When performing work it is necessary:
- remove insulation at an angle less than 90 degrees;
- act carefully if the cable material is aluminum;
- strip the insulation for a joint equal to 3-4 cm;
- lay two cables on top of each other 1.5-2 cm above a bare place at an angle of 45 degrees;
- holding the area above the cut with your left hand, begin to twist the veins;
- work so that at first there is a twist with insulation, and then a bare length;
- finish the twisting process with pliers for extra density.
Ready twisting can not immediately be covered with insulation. The line should work for 2-3 hours. After that, you need to turn off the machine at the input and check the temperature of the unit. Heating indicates the unreliability of the mount - it will need to be redone.In the absence of heating, the conductors can be insulated.
Wire Twisting Tools
To properly twist the wires together, you will need:
- stationery or kitchen knife;
- nippers or side cutters;
- stripper;
- hydraulic or manual type crimper;
- soldering iron - to remove insulation;
- heat shrink tube;
- building hair dryer;
- screwdriver.
Instead of a soldering iron, you can use an electric burner.
Operating procedure
A phased twisting algorithm can be considered on the example of a plexus of a multi-core and single-core cord. In this case, it is better to work in the branch technique:
- Stripping the area from the end of the conductors - 3-4 cm long with a stripper or clerical knife.
- Placement of heat shrink on one of the cables.
- Degreasing segments without insulation with a special tool.
- 180 degree bending of the single-core end to further tighten the twist.
- Wrapping a multi-core cord over a single-core. It will take 5-6 turns clockwise.
- Clamping the bent single-core tip with pliers and pressing it to the connection.
- Placement of heat shrinkage at the place of twisting and fixing it with a building hair dryer.
Shrinkage should tightly fix the twist.
Compound insulation
Insulate the resulting node must be of high quality. Three technologies are used for this purpose.
Insulation tape
The tape with a sticky base is made of polyester and epoxy film, fiberglass and mica, acetate material and paper. For insulation of the household power supply, a tape with class P PVC film and rubber adhesive side is suitable. The material has good adhesion, elasticity and density. Closing the twist with electrical tape is carried out step by step:
- Winding starts 2-3 cm above the exposed area, on top of the wire insulation.
- The tape is wound at a slight angle towards the end of the twist.
- In place of the tip, the material bends around it and wraps in the opposite direction.
- After the place of winding, the tape is cut with a clerical knife or scissors.
Two-layer coating with insulating tape will ensure reliability and maximum tightness of the contact joint.
The electrical tape is suitable for twisting electric cords located in a dry room.
Heat Shrink Tube
The thermotube is made from special polymers, which are compressed and expanded under conditions of blowing with hot air or from exposure to warm water. Heat-shrinkable material can be placed on top of objects with complex terrain. When working with strand cores, products provide high-quality insulation and protect against tearing.
The isolation process is carried out as follows:
- A piece is cut from the tube, 1 cm more than the exposed area.
- A piece is put on 1 wire before the seam begins.
- The cable is twisted.
- After twisting the cores, the thermotube is pulled to the twisting site.
- A tube is heated by a building hairdryer or lighter at a distance of 1-2 cm. Under the heat stream, it will decrease and will be pressed tightly to the site.
Conductors insulated with thermotube, according to GOST, can be laid in the bathroom, immersed in soil or water.
Building Insulation Clamp
When organizing home or apartment wiring, it is advisable to use special PPE caps. Products are put on a place for isolation after twisting. The tip of the cap is cut off, and the PPE itself is put on the wire with effort. Special springs on the surface open and tightly wrap around the joint. For added strength, you can turn the cap clockwise.
When using PPE, the twisted section can not be soldered.
Professionals Recommendations
Experienced electricians give some tips on how to apply twisting and consider all the risks of such a connection.
PUE permits
Standards cannot completely ban twisting. It can be used in combination with technologies:
- welding: twisted wires are additionally soldered to ensure continuity of contact;
- soldering: solders cannot give the joint mechanical strength. For this reason, the cores are twisted, soldered, insulated and placed in a distribution box.
For extra density of twisted cores, use screw terminal blocks.
Connection of conductors from different materials
It is forbidden to combine copper and aluminum in one twist. Between them there is a galvanic couple, which is subjected to electrolysis under the influence of moisture and chemical processes. The resistance of the broken contacts increases, and then disappears. As a result, the seam heats up and burns.
The difference in the thermal expansion coefficients of the material will lead to weakening of the seam after cooling. Resistance begins to increase more intensively.
The appearance of oxide film
Aluminum is a material on the surface of which an oxide film always appears. It enhances cable protection, but also increases contact resistance. To exclude it, the veins are covered with quartz-vasilin paste or they acquire special terminal blocks with this filler.
Twisting, as a type of connection of conductive conductors, is allowed to be used only as a temporary measure. In conditions of constant operation, the seam can lead to a fire in the wiring, fire hazard situations.
