Why is the outgoing line of the distribution box under the transformer not using insulated wires, but usually using cables
According to the Safety Regulations, low-voltage insulated conductors are considered as bare conductors. The cable is wrapped in a double layer of insulation skin, and the outer skin can be safely contacted under live conditions.
Insulated wires are often used for overhead lines and must be able to withstand a certain amount of tension. Therefore, in the aluminum core of insulated wires that we often use, there is one or more strands of steel core in the middle to increase the tension. Therefore, the wires are often relatively hard, and it is difficult to operate when used for outgoing lines in distribution cabinets. Moreover, in order to reduce weight, aluminum cores are often used. Compared to copper materials, aluminum wires have a much thicker electrical load, which increases the difficulty of operation.
Firstly, the cable has an additional layer of sheath than the wire, and armored cables also have steel armor installed inside the sheath to enhance strength. So cables have better strength than wires and higher insulation levels.
Secondly, cables are multi-core and easy to lay, while wires are single core and require conduit laying, which can be quite troublesome.
Why do the outgoing lines of the distribution box under the transformer usually use cables instead of insulated wires?
Finally, the cross-sectional area of the wire generally does not exceed 16 square meters, while at the transformer, the current carrying capacity is high and the wire cannot meet the current carrying capacity requirements.
Why do we usually use cables instead of insulated wires for the outgoing lines of the distribution box under the transformer?
The cross-sectional area of the transformer is relatively large, and cables are usually used for sections above 35. In addition, transformers are generally far away and the working conditions are relatively complex, making cables more suitable.
