How to Calculate the Wire Gauge

All electricians should know how to correctly size electrical conductors, but in reality, they are not all. Whether because of not having enough knowledge or because there are many doubts regarding the gauge of electrical cables.

There are several doubts, such as how to calculate the wire size, which wire to use for the socket, how many amperes a particular wire supports and how to interpret the voltage drop table? We will clarify all these doubts and the like in a simple way, come on guys!

One of the main factors for obtaining a good quality electrical installation is to determine the correct wire size for the conductors according to each circuit. The poor dimensioning of the conductors, besides interfering directly in the efficiency of the installation, providing fire risks, due to the heating of the cables and conduits.

The first step in making a correct dimensioning is to determine the total number of loads and the respective circuits, in addition to knowing the total power dissipated by the installation, of each circuit and its respective loads.

The factors that determine what the conductor’s gauge should be are many, such as the distance from the QDC to where the load is connected, the temperature and especially the current that passes through that conductor.

In order to know which current will pass through the conductor is simple, each electrical and electronic equipment dissipates a certain power, which is the relationship between this power and its supply voltage that will establish the value of the electric current.

The standard NBR-5410 stipulates some criteria that must be taken into account when dimensioning an electrical conductor. The standard stipulates minimum conductor sections for each circuit of the installation, and for lighting circuits, it requires a conductor of at least 1.5, load circuit with a conductor of at least 2.5 and signaling and control circuits of at least 0 , 5. It is important to note that these values ​​are minimum requirements, that is, for certain functions, cables with lower gauges cannot be used.

The first step in determining which cable should be used is to add up all the powers in the installation, such as the lamps and the possible equipment that will be used, that total power that will determine the voltage value of your installation that will determine the total current of the circuit. The gauge of this conductor will be the largest, as this is the cable that leaves the meter going straight to the QDC.

Electric current is a determining factor when choosing the correct conductor but in ad

All electricians should know how to correctly size electrical conductors, but in reality, they are not all. Whether because of not having enough knowledge or because there are many doubts regarding the gauge of electrical cables.

There are several doubts, such as how to calculate the wire size, which wire to use for the socket, how many amperes a particular wire supports and how to interpret the voltage drop table? We will clarify all these doubts and the like in a simple way, come on guys!

One of the main factors for obtaining a good quality electrical installation is to determine the correct wire size for the conductors according to each circuit. The poor  dimensioning of the conductors, besides interfering directly in the efficiency of the installation, providing fire risks, due to the heating of the cables and conduits.

The first step in making a correct dimensioning is to determine the total number of loads and the respective circuits, in addition to knowing the total power dissipated by the installation, of each circuit and its respective loads.

The factors that determine what the conductor’s gauge should be are many, such as the distance from the QDC to where the load is connected, the temperature and especially the current that passes through that conductor.

In order to know which current will pass through the conductor is simple, each electrical and electronic equipment dissipates a certain power, which is the relationship between this power and its supply voltage that will establish the value of the electric current.

The standard NBR-5410 stipulates some criteria that must be taken into account when dimensioning an electrical conductor. The standard stipulates minimum conductor sections for each circuit of the installation, and for lighting circuits, it requires a conductor of at least 1.5, load circuit with the conductor of at least 2.5 and signaling and control circuits of at least 0 , 5. It is important to note that these values ​​are minimum requirements, that is, for certain functions, cables with lower gauges cannot be used.

The first step in determining which cable should be used is to add up all the powers in the installation, such as the lamps and the possible equipment that will be used, that total power that will determine the voltage value of your installation that will determine the total current of the circuit. The gauge of this conductor will be the largest, as this is the cable that leaves the meter going straight to the QDC.

Electric current is a determining factor when choosing the correct conductor, but in addition, we must calculate the voltage drop that occurs in the cables. The voltage drop is an anomaly caused by the distance that the electric current travels in a given circuit, the greater the length of the conductor the greater the voltage drop, due to the increase in electrical resistance and the amount of material used to make conductors bigger.

Another factor that influences the voltage drop is the inductive reactance, caused by non-resistive loads. However, it is considered for small consumers and small loads that the electric current is distributed evenly among the conductors despite the magnetic field generated.

To make it easier, we have provided some tables to follow that just analyze it to know which driver to use, without the need to perform calculations for voltage drop.

Sizing table for electrical conductors (two-phase).

Example:

We will determine the gauge of a conductor from the meter output to the QDC input, whose voltage is 127V. Just know the distance between the meter and the switchboard. Assuming that this installation the current is 60A with the distance between the meter and the QDC is 20 meters, with the cables passing through an conduit, when analyzing the table in a simple way we see that the conductor section is 16mm, as shown the table below.

Sizing table for electric conductors (single-phase).

If you want to know more about how to dimension electrical conductors, below is a video on how to dimension cables in 5 steps:

We finish this article here and we hope to have cleared all doubts about how to calculate the wire gauge! If you still have any questions on this subject, leave it in the comments and we will respond!

edition we must calculate the voltage drop that occurs in the cables. The voltage drop is an anomaly caused by the distance that the electric current travels in a given circuit, the greater the length of the conductor the greater the voltage drop, due to the increase in electrical resistance and the amount of material used to make conductors bigger.

Another factor that influences the voltage drop is the inductive reactance, caused by non-resistive loads. However, it is considered for small consumers and small loads that the electric current is distributed evenly among the conductors despite the magnetic field generated.

To make it easier, we have provided some tables to follow that just analyze it to know which driver to use, without the need to perform calculations for voltage drop.

Sizing table for electrical conductors (two-phase).

Example:

We will determine the gauge of a conductor from the meter output to the QDC input, whose voltage is 127V. Just know the distance between the meter and the switchboard. Assuming that this installation the current is 60A with the distance between the meter and the QDC is 20 meters, with the cables passing through an conduit, when analyzing the table in a simple way we see that the conductor section is 16mm, as shown the table below.

Sizing table for electric conductors (single-phase).

If you want to know more about how to dimension electrical conductors, below is a video on how to dimension cables in 5 steps:

We finish this article here and we hope to have cleared all doubts about how to calculate the wire gauge! If you still have any questions on this subject, leave it in the comments and we will respond!