Electrical conductors ( electrical wires ) are the line that transmits electricity between the source and the load to be operated. Electrical conductors are available in the labor market in different sizes, and the cross-sectional area of ​​the conductor is important in relation to the value of the electric current.

Sizes of electrical wires used in household electricity and their loads

Suppose we have a water hose with water rushing through it, but this hose has a specific tolerance level. If the pressure and amount of water flowing through the hose increases, the hose will be damaged because it will no longer allow this amount of water to pass through at this pressure. Electrical wires are similar to water pipes in terms of cross-sectional area. The greater the cross-sectional area (i.e., the wider the mouth of the tube, the smaller its resistance becomes, and a large water current passes through it.

Conversely, the smaller the cross-sectional area (i.e. the tube becomes narrow), the greater its resistance becomes, and a small water current passes. Likewise in electricity, if we want to pass a small current, the cross-sectional area of ​​the wire will be small (for example, a wire with a cross-sectional area of ​​3 square millimeters passes a larger current than a wire with a cross-sectional area of ​​2 millimeters square, etc. If the wire is not suitable (i.e., has a small cross-sectional area) and we want to pass a large current through it, two problems will certainly occur:

• Either the wire becomes very hot and melts and its insulating material melts, which may cause a fire.
•  Some voltage (voltage) may be lost in the wire itself, and thus the device (for example, a light bulb) does not receive the full rated voltage, so the lights become dim, or the performance of the device becomes weak, and thus it does not perform the purpose for which it was used.

Sizes of electrical wires used in household electricity and their loads

The electrical wires used in household connections are usually made of copper insulated with plastic, and their cross-sectional area varies depending on the intensity of the current passing through them. For example, a wire with a cross-section of 1.5 mm is used for telephones, electric bells, clocks, and intercoms . While wires with larger sections of 6-10 mm are used for devices with large capacities such as air conditioners, ovens, and heaters, as they are connected directly from the main distribution panel to those devices with large loads. 

 Therefore, it is necessary for everyone who works in home electricity to know and understand well the sizes of wires used in home electricity and their loads, meaning that one must know how to estimate electrical loads and then choose the appropriate conductor based on the value of the electrical current expected to pass through the electrical circuit. To know the wire sizes and their loads, This is done using special tables, as we will explain.

Wire bearing table for electrical current

The electrical connectors used in home wiring and others are manufactured according to standard specifications, including the American system for determining conductor diameters and the European system. The following table shows us the sizes of electricity wires and the current intensity of the wire in amperes in both the American system and the corresponding cross-sectional area of ​​the European system. Note that the table shows copper wires.

Electrical wire sizes

We find that in the American system, the higher the conductor number, the smaller its diameter, while the European system relies on the metric system.

Some American sizes have equivalents to European sizes in square millimeters, and when choosing a European connector instead of an American connector or vice versa, its current should be equal to the current of the original connector.

Note from the table that the smaller the diameter number of the American wire, the greater the ability of the wire to carry electric current. For example, the wire bearing the number (14) carries a current of 15 amps, while the wire bearing the number (12) (a larger diameter wire) carries a current of 20 amps.

The diameters of the wires are written on the wire itself for the European system and the connector number for the American system, especially the large ones. However, the small conductors do not have their size value written on them due to their small size. Therefore, a wire diameter measuring tool can be used to determine the diameter of the wire.

Below is  a table of electrical wire loads 

Electrical wiring load table

The previous table shows the sizes of copper conductors in millimeters, the number of filaments that make up the wire, its diameter in inches, and the amount of its load in amperes.

The following table shows the colors of wires according to British and international specifications

Wire colors according to British and international specifications

Note that

• Current endurance capacity: It is the ability of the wire to withstand the flow of load current under normal operating conditions, and to withstand currents resulting from faults.
• Temperature is what limits current carrying capacity the most; The highest temperature that PVC insulation can tolerate is (70) degrees Celsius, and the highest temperature that XLPE insulation can tolerate is (90) degrees Celsius.
• The value of heat loss depends on the surrounding environment, the method of cable identification, and the number of cables within one group.