The electrical panel is the central nodal element of the power electrical network and, in fact, is its heart. The reliability of the network as a whole largely depends on the quality of its assembly.
Any electrical wiring as a system is unique and the use of a completely finished electrical panel in a full factory configuration is impossible in principle. The shield must be assembled on site, taking into account the specific local conditions.
Under these initial conditions, it is necessary:
- use of high-quality element base;
- good elaboration of the project in compliance with all the rules;
- careful installation.
The use of cables in this case is redundant. The wire that is used to connect the individual elements inside the switchboard is a mandatory component and is fully subject to all quality requirements. What should be understood by the definition of "quality"?
Basic requirements for the wire
When forming a shield, you cannot use a wire with aluminum conductors. This is determined by the large number of bends during installation, which are accompanied by an increased risk of core breakage due to the low bending resistance of aluminum.
Wires with copper conductors can be either rigid single-wire or flexible multi-wire.
The main advantage of a single-wire wire is the possibility of direct insertion of the end stripped from the insulation into the screw terminal of the elements. The main disadvantage is low flexibility, especially with a cross section of 6 mm2 and above, which complicates installation in hard-to-reach places.
Features of the use of flexible wires
Wires with stranded conductors are highly flexible, but before inserting them into a screw terminal, they must be terminated with a tip of the NSHVI type or similar (see. Figure 1) or tin-plated.
In circuits with a high current load, the use of tinning is not recommended due to the ultimate risks of heating the contact area and leakage of solder, which is accompanied by a loosening of the clamp. A similar effect in severe cases can even cause a fire.
Wire marks
The above criteria impose fairly mild restrictions on the wires that can be used. In real practice, due to their parameters and the massiveness of the offer, such cable products as:
- single-wire first class of flexibility wire PV-1 with vinyl (PVC) insulation (Figure 2);
- multi-wire of the third or fourth (depending on the cross-section) class of flexibility PV-3 wire also with vinyl insulation.
- stranded wire PV-4 increased to the fourth and even the fifth class of flexibility with a minimum bending radius of five outer diameters, the design of which is shown in Figure 2).
The operating voltage of all listed products is 450 V at a frequency of 50 - 400 Hz, the operating temperature range is from -50 to +70 ° C. The insulation is available in various colors, incl. yellow-green, which is standardized for grounding circuits. An example of such a product in relation to the PV-1 grade is shown in Figure 3.
All of the wires listed above, due to the appropriate additions to the plastic of the sheath, correspond to a fire safety class of at least LSZH.