Size of Cable for a Given Load

Size of Cable for a Given Load Points : Size of Cable for a Given Load To determine the correct size of a cable for a given load, we concern the tables of electric cables. In this, current carrying capacity of a able,’ Voltage drop in cable: temperature factors are given. Some points are given below, are very important to determine the correct size of a cable.
(i) It is noted that the temperature changing are effected on the cable.
(ii) Behind of known load current, adding 20% extra current for future extension.
(iii) From energy meter to distribution board voltage drops are 1.25% and for final sub circuit the voltage drop are not exceed than 2.5%
(iv) To calculate the correct size of cable load factor is very important.
(v) Wiring system is also very important factor for cable size. Obviously for cables enclosed in conduit, there is not free flow f air past the cables to cool them.
The air inside the conduit is static and so hot much cooling is available. However, if cables are run on open wiring means cleats, especially if they are run horizontally, air can pass freely around each cable and given maximum cooling. We know that the change in temperature is effected on cable size.
Ambient temperature = The temperature of air or material surrounding a cable.
Conductor temperature = The temperature of the conductor of a cable when current is passing-through it.
Conductor temperature = Ambient temperature + temp rise due to current.