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How to choose the right wire and cable model and cross section

Updated:14-12-2020
Summary:

It depends on what type of wire and cable to use, inclu […]

It depends on what type of wire and cable to use, including bare wires, insulated wires, heat-resistant wires, shielded wires, power wires, control cables, etc. Commonly used like PVC insulated wire, PVC insulated flexible cord. Fires caused by overloaded cable and wire are not uncommon, and they are also diverse. Such as short circuit, overload, leakage, poor contact and other factors.
   Wires with only insulating layers are usually called "wires", and those with not only insulating layers but also sheaths are called "cables".
   Common wire and cable models are: BV, BLV, BVR, RV, RVV, RVVP, RVS, etc.
  BV or BVR can be selected for wiring in home decoration. BV line is harder, but its overload capacity and weather resistance are much better than BVR. Compared with BV lines, BVR is softer, has strong flow capacity, more convenient construction, and more expensive.

Since the BV wire is a single-stranded wire and compared with the BVR of the same cross-sectional area, its copper wire is thicker, and it is not easy to burn when the temperature is high for a long time; the copper wire of the BVR wire is relatively thin, and one of them is easy to burn when the temperature is high. Two roots. As long as one or two copper wires in the wire are burned, the burned cross-sectional area is reduced, the resistance is greater, and the wire is more likely to be burned.
   In practical applications, because the BVR line is relatively soft, the connector is easy to loosen after a long time; while the BV line is relatively better, so in order to prevent the connector from loosening, the "hanging tin" process must be adopted in home decoration.
  VV cables and YJV cables are generally used in factory power distribution. Among them, VV cables can only be used in normal temperature environments, while YJV can be used in higher temperature workshops with a heat-resistant temperature of up to 90 degrees.
   The control cable is RVV cable. If there is a strong magnetic field or electric field around, you need to use shielded cable RVVP. The fire-fighting system generally chooses the twisted pair RVS, which is also called the "flower line".
   Wire and cable are divided into copper core wire BV series and aluminum core wire BIV series by material, and the common cross-sectional area ranges from 1.5mm to 120mm.
  Choose the wire and cable cross section according to the load calculation rated current. Taking the family as an example, the electrical appliances used have inductive loads and resistive loads, so the calculated rated current is P=UI and P=UIcosΦ.
  Assuming that the total power of home appliances is 10KW, the calculated current I is 56A. As we all know, home appliances cannot work at the same time, so a simultaneity coefficient of 0.6-0.8 should be given. Therefore, the coefficient is 0.8 and the calculation is 45 amperes. So the total power cord at home can use 6 square millimeter copper core BV series wire and cable.

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