How do you calculate wire caliber?

[KundaliniZero]

Guys

I am new. I have a basic question. How do you calculate wire caliber or seccion in low voltage distribution?

In my country (220 v, 50hz) I have seen two form:

1. Use a computer program to stimate. So the caliber depend on nominal current, short circuit and drop of tension.

2. Manual calculation based on the same parameters but when i select a nominal current, chose a circuit breaker. Then if it is 28 A. The general CB will be 32 and because selectivity the far CB will be 40 A. The seccion of the wire between them will be calculated for 40 A and not the nominal current. This method is used in some industries in my country.

The main difference is the first use nominal current and the second one the current of the circuit breaker. So there will be economical differences.

How do you do?

 

[jglavin PE]

In the USA we follow the building code, the national electrical code (published by the NFPA).

Per the NEC, for motors you can generally use the load (nominal) current to size the conductor - since motors are equipped with overload protection. For other loads, you generally size based on the overcurrent protection. Sometimes you can go to the "next standard" size breaker depending on the situation, which saves a little on wire since it doesn't need to be as large, but the conductor must always be sized to carry the load.

 

[KundaliniZero]

So you do the same way than us

Enviado desde mi GT-I9195 mediante Tapatalk

 

[SakshiVerma]

To calculate the caliber of a wire, you need to know its cross-sectional area. The cross-sectional area of a wire is determined by measuring the width and the height of the wire and then using the area of a rectangle formula: width x height. Once you have the cross-sectional area of the wire, you can use the formula for the wire's caliber, which is the square root of the wire's cross-sectional area divided by pi. For example, if the width of the wire is 0.5 inches and the height is 0.25 inches, the cross-sectional area would be 0.5 x 0.25 = 0.125 square inches. The caliber of the wire would be the square root of 0.125/pi, approximately 0.16 inches.