Measures to prevent fire when installing electrical wires

The following fire safety measures must be observed during electrical work:

• Pipes must be plastered with a continuous layer 10 mm thick.

• A continuous layer of non-combustible material around the pipe (box) can be a layer of plaster, alabaster, cement mortar or concrete with a thickness of at least 10 mm.

• The connection, branching and termination of the wires is carried out by welding, soldering, pressing or special clamps (screw, bolt, wedge, etc.)

As practical experience has shown, the easiest, cheapest and most reliable way to connect or connect aluminum and copper wires is crimping (cold soldering).

Connection and crimping of multi-core and single-core aluminum and copper wires with a cross section of 16-240 mm. Connect wires to aluminum wires with GA-type ferrules using crimps MGP-12, RMP-7M, etc. End fittings and connecting sleeves are selected in accordance with the requirements of GOST.Electrical connections of wires with wires with a cross section of 2.5-10 mm2 in the lines of intra-apartment networks should also be carried out, as a rule, by crimping, using aluminum sleeves of the GAO type crimping pliers PK-1M, PK-2M or portable hydraulic tongs of the GKM type.

Case selection is determined by the total cross-section of the wires to be connected; if necessary, additional (ballast) wires can be installed to fill the volume of the sleeve. Connecting and branching wires using GAO bushings can be done with one-sided or two-sided entry of the wires into the bushing. When two-sided introduction of wires into the sleeve, the length of the latter is doubled, and crimping is carried out through two recesses.

In preparation for crimping the terminals (or ferrules) and wire ends to the length determined by the tip size, the insulation is removed from the wire and the exposed area and inner surface of the tip (ferrule) is cleaned. Aluminum parts are cleaned with metal brushes and covered with protective grease (contacts). Currently, conductive adhesives, paints, enamels are widely used, where synthetic resins are used as a binder, and metal powders (silver, nickel, zinc, etc.) are used as conductive components. The most available are the KN-1, KN-2, KN-3 contacts, which are characterized by high stability in the contacts of aluminum wires.

Connections with twisted wires must be completely excluded from the practice of electrical work.

Termination of solid copper wires, wires with a cross section of 1-10 mm2 and multi-wire with a cross section of 1-2.5 mm2, as well as aluminum wires with a cross section of 2.5-10 mm2, when connected to devices and devices, is carried out by bending on the end of the wire in a ring. The ring must be twisted in the direction of screwing, otherwise the ring will loosen when screwing. Aluminum wire requires special attention. As you know, aluminum «flows». Therefore, without maintaining a constant pressure and limiting the extrusion of the wire, the contact will break. When assembling the contact connection, a flat washer is placed under the head of the screw, then a spring washer, behind it a clamp or washer with sides, a wire ring is placed between the sides.

When connecting two wires with a screw, a flat washer is placed between their rings.

The installation of wiring accessories, which is widely used now in apartments, in which they are fixed with remote ears, very often does not guarantee the reliability of the fastening and the safety of the product (switches, sockets). With a high density of wires connected to the wiring product, the forces applied to its body are transmitted to the contact, become loose and can lead to overheating of the contact or short circuit in the network. In order to improve their performance during long-term operation, the necessary contact pressure is provided by spring washers and rigid attachment of wiring accessories.