Recently, the question of the correct determination of the cable cross-section has become especially relevant, since all the ratings of the circuits for certain needs have become strictly regulated, and the slightest deviation from GOSTs, OSTs and TUs entails strict sanctions from various commissions.
Necessary
vernier caliper
Instructions
Step 1
However, the correct selection of the wire cross-section is important, first of all, not for the inspection organizations, but for the user (consumer) himself. A competent approach at the design stage of the electrical network, as well as during its laying, will not only protect a person from the effects of electric current due to damage to the cable, but also a fire that has arisen due to deterioration of the insulation. In addition, you can avoid material costs for the purchase and laying of a new cable to replace the old one that is out of order.
Step 2
According to regulatory documents, all voltage circuits must be laid with wires with a cross section of at least 1.5 squares, current circuits - 2, 5, and grounding - 4. Power supply sources are calculated according to a number of criteria: from the length of the line to the load that will be connected to this chain.
Step 3
There are several ways to determine the cable size. Firstly, if you want to connect several low-power sources (lamp, bell, TV), then you can safely use a regular two-core (three-core) wire, for example, KVVG in 1.5 squares.
Step 4
However, when laying a cable for a washing machine or an outlet to which a refrigerator, microwave oven and toaster will be connected at the same time, you should use a cable with a cross section of 2.5 mm ^ 2 in double insulation, since the value of the currents flowing in the circuit will increase several times … Thus, the heating of the wires will increase. This will be followed by a gradual destruction of the core insulation, which, in turn, will lead to a short circuit.
Step 5
For grounding, a stranded copper wire with a cross section of 4 squares is suitable. As a rule, it has a yellow-green isolation color. But if you have several conductors of a smaller cross-section, then they can be quite used by connecting them in parallel to each other. The main thing is the total cross-sectional area of copper veins.
Step 6
In case of difficulties with the visual method of determining the required size of the cable cores, you can use a vernier caliper. To do this, carefully strip the tip of the guide wire and take a measurement.
Step 7
If you are dealing with a stranded copper cable without insulation, then its cross-section can be approximately determined with the same caliper. To do this, it is necessary to roll the copper conductors into a tight bundle and measure the thickness of the twisted wires. For a more accurate calculation of the cross-sectional value, you can measure the thickness of one of the cores, and then multiply the result by the total number of conductors that will have to be recalculated manually.
Step 8
However, it should be noted that according to the rules of technical operation (PTE), the use of such conductors is prohibited. Therefore, when laying any electrical circuits, double insulated cables should be used. In addition, in open areas exposed to atmospheric precipitation, it is necessary to lay wires tucked into a metal hose or laid in a cable channel.
