How is the calculation of electrical load

Before you begin to design the electricians in your home, apartment, or dacha, you must first make a calculation plan, which will indicate all the expected loads in the premises, as well as the length of individual sections of the cable. To compile such a map, you will also need to calculate the electrical load. Correctly designed scheme of the electrical system of the object will allow to select wires and cables of required cross-sections. In those cases where the cross-sectional area of the cable is less than required for the normal functionality of high-power power units, the cable begins to overheat. And as a result, the insulation is destroyed. As a result, the duration of operation and the reliability of the wiring are significantly reduced. Moreover, overheating of the cable can lead to ignition. Similar situations happen very often, when the tenants (for the sake of economy) use a wire cross-section that is less than necessary. As a result, short circuits and fires occur. Let's figure out what the calculation of the electrical load is.

The correctness of the choice of switching devices, as well as the cross-section of the cable, largely depends on the different values of the parameters of the electrical networks. The most important of these is the electric current of the load. At the design stage, this value can be determined exclusively by a mathematical method. It is very important to calculate the electrical load in three-phase networks, since the load in them must be placed evenly among the phases in order to avoid distortions of voltage. However, in household networks, such a calculation should be carried out when designing not only the panel, but also the living quarters.

The calculation of the electrical load is carried out at known values of the power of electrical devices, the nature of the loads, as well as the voltage of the network. For single-phase networks use the formula for determining the load current: I = P / (U × cosφ), where:

• U - the value of the actual network voltage (measured in volts);
• Cosφ is the corresponding power factor.

For three-phase networks, the calculation of electrical loads is carried out according to the following formula: I = P / (1.73 × U × cosφ).

Depending on the nature of the load, the value of the power factor is selected. When calculating a high-power reactive load (chokes of lighting devices, electric motors, welding transformers, etc.), an average value of cosφ = 0.8 is adopted. When determining the power current for the active loads (heating elements, incandescent lamps), the power factor is approximately equal to unity. However, in any active load, a reactive component is always present, so it is customary to use cosφ = 0.95 for calculations.

In conclusion, we recall that electricity does not forgive mistakes, it will not give a second chance. Safety, as well as the reliability of electrical systems - that's what any professional electrician strives for. And it does not matter where he works: in industry or in the private sector. Electric load is one of the most important design parameters that must be taken into account in any system.