Electrical wiring must meet the requirements of safety, reliability and efficiency. Therefore, it is important to correctly calculate the length and cross section required for the installation of electrical wiring harness. Wire length is calculated from the circuit board. For this scheme to measure the distance between adjacent locations panels, sockets, switches, junction boxes, etc. Then, using a scale in which vycherchena scheme, calculate the lengths of wires, to the length of each segment is added at least 100 mm (case need to join wires). Length of wire can be calculated also by measuring directly on the panel, panels, walls, ceilings, etc., segments of lines along which the wires must be routed. Conductor cross-section calculated from the loss of voltage and allowable long-term load currents. If the calculated cross sections will be unequal, then for the final result takes the value of a larger utterance. The loss of voltage due to voltage drop in the wires connecting the power source to power consumers. It should not exceed 2 - 5% of nominal voltage power supply. Cross-section of the voltage loss is calculated in the design of electrical networks, which are fed by power-consuming equipment of industrial enterprises, transport, major residential and public buildings, etc. In the design of small electrical installations, electrical installations such as individual rooms, improvised devices, etc., the loss of voltage in the wires can be neglected, since it is very small. To calculate the cross wires on the permissible continuous current load is necessary to know the rated current, which must pass through the projected electrical wiring. Knowing the rated current, cross the wires are on the table. Cross-section conductor, mm2 current for wires and cables with copper conductors, and the current for wires and cables with aluminum conductors, A Two-stranded single-core Two-Three-Three-When laying воздухвоздухземлявоздухземлявоздухвоздухземлявоздухземля 1.5 23 19 33 19 27 - - - - - 2 , 5 30 27 44 25 38 23 21 34 19 29 4 41 38 55 35 49 31 29 42 27 38 6 50 50 70 42 60 38 38 55 32 46 10 80 70 105 55 90 60 55 80 42 70 16 100 90 135 75 115 75 70 105 60 90 25 140 115 175 95 150 105 90 135 75 115 35 170 140 210 120 180 130 105 160 90 140 50 215 175 265 145 225 165 135 205 110 175 70 270 215 320 180 275 210 165 245 140 210 95 325 260 385 220 330 250 200 295 170 255 120 385 300 445 260 385 295 230 340 200 295 150 440 350 505 305 435 340 270 390 235 335 185 510 405 570 350 500 390 310 440 270 385 240 605 - - - - 465 - - - - Example: The rated current is 50 A, a section of copper conductor line cord laid on the air should be 6 mm 2. Rated current and acceptable long-term current loads specified in the table may not match in size. In this case the cross section is found by the nearest higher rated current allowable continuous load currents. Example: on the wire must pass the rated current of 74 A, the nearest big-largest allowable long-term current carrying capacity 80, 75 A (see Table.) Means required to carry out section 10 - 16 mm2 (depending on how the gasket), if the core of his brass, or a section of 10-25 mm 2 (depending on how the gasket), if the aluminum wires. If the rated current is not known beforehand, it can be determined using calculations described in the article about the circuit breaker. Mark Cable Mark Cable (Wire) - is the drive letter, characterizing the material of conductors, insulation, flexibility and design of protective covers. The marking of domestic wire, the following notation: the first letter indicates the material of conductor (eg, A - Aluminum), lack of brand wire the letter means that the conductor is made of copper, the second letter denotes the wire and the third - the insulation material (eg, P - rubber, - PVC, P - PE). In brands of wires and cords can also be present letter describing other structural features: About - Braid, T - for laying the pipes, P - flat, F - fanfold metal shell, T - a flexible, etc. The main types of cable used for Wiring Flat two-and three-core copper wire PPV: the section from 0.75 to 4 mm ?, rated voltage 380 V, separating the base, PVC insulation. Suitable for installation of lighting and power circuits in a fixed open wiring. Power cable AVVG: aluminum conductors (1-4), the cross section from 2,5 to 50 mm ?, PVC insulation, PVC jacket. Intended for installation in dry and in wet areas. Power cable VVG: copper wires (1-4), the section from 1 to 50 mm ?, PVC insulation, PVC jacket. Used for installation in dry and wet areas. Flat two-and three-wire aluminum wire APPV: a section from 2,5 to 6 mm ?, rated voltage 380 V, separating the base, PVC insulation. Used for the installation of lighting and power circuits in a fixed open wiring. Single core copper wire PV1: a section from 0,5 to 95 mm ?, rated voltage 380 and 660, PVC insulation. Used for wiring lighting and power networks within the home. Cable VBbShv: copper conductor PVC on, PVC jacket, armor made of galvanized steel strips, hermetically sealed outer tube. Can be used wherever there is a risk of mechanical damage to wiring during operation. PV3 solid wire: copper conductor increased flexibility, the cross section from 0,5 to 95 mm ?, rated voltage of 380 and 660, PVC insulation. It is used for lighting and power wiring network within the home. Possible to both open and hidden strip in situations where you need greater flexibility in the wire. Single core copper cable runway: plastic insulation on the conductor, PVC jacket. Used to vodopogruzhnyh engines. Cable CT: Copper stranded conductors, rubber insulation, rubber jacket. Is used where the cable is required elevated gibkosti.Opublikovano 23/04/2008 Articles on "Electricity, lighting, security systems"
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