In our daily life, we use a variety of electrical appliances that require different wires and cables, the selection and placement of which requires special knowledge and rules. When choosing a cable or wire, you need to be guided by the main criterion - the goods are purchased only from manufacturers of well-known brands and have proven themselves in the field of reliability and quality.
Instructions
Step 1
In residential premises, wire of the PVS brand and cables of such brands as VVG, NYM and VVGng are mainly used. PVA wire is a twisted, round cross-section, copper wire. It is used to connect power tools and household electrical appliances, in gardening. The wire is laid at temperatures from -15 ° C to + 40 ° C. The wire is insulated with PVC-plastic. The core is copper, flexible.
VVG refers to power cables. I use it in stationary installations for the distribution of electrical energy with voltages from 0, 66 to 1 kV, in the temperature range from -50 to +50 degrees and humidity up to 98%. VVG cables are used for laying in household and industrial premises, both in dry and wet.
VVGng cable differs from VVG in that its sheath is made of heat-resistant materials, therefore it is used at facilities with increased requirements for electrical and fire safety.
The core of the VVG and VVGng cable is made of round soft copper wire. With an increase in cross-section over 16 sq. Mm, the core is made in the form of a lot of wire bundle.
And finally, NYM brand cable. Thanks to the additional layer of melo-rubber insulation on this cable, its resistance to cracking increases when installed in extreme conditions. The outer insulation is made of a more flexible plastic compound, which leads to increased safety. Due to these qualities, the popularity of this cable is constantly growing.
Step 2
The cross-section of the cable is the area of the conductive core. According to the formula π (= 3, 14) xr2, the cross-section of a round conductor is calculated. In a cable, as a rule, there are several cores, so the total cross-section is equal to the sum of the cross-sections of each core. A vernier caliper and a micrometer are used to measure the diameter of the wire.
The cable cross-section is selected taking into account the future load. However, it should be borne in mind that the cross-section of the aluminum wire should be selected an order of magnitude higher, since its conductivity is 40% lower than that of a copper wire. Basically, standard types of sections from 0.75 to 10 mm are used.
To select a cable taking into account the load, special tables are used, however, experienced electricians use a simplified calculation of the wire cross-section: a cable with a cross-section of 1 mm2 can withstand a current of 10A and a power of 2.2 kW (10Ax220V = 2.2 kW).
Example: your electrical appliance has a power of 8 kW, the current strength is 36A, respectively (8000W: 220V = 36A), it follows that the cross-section of the wire should be 4 sq. Mm (36A: 10A = 3.6 mm2, standard is 4 sq. Mm).
