Installed power (kW)

The installed power is the sum of the nominal powers of all power consuming devices in the installation. This is not the power to be actually supplied in practice.

Most electrical appliances and equipments are marked to indicate their nominal power rating (Pn).
The installed power is the sum of the nominal powers of all power-consuming devices in the installation. This is not the power to be actually supplied in practice. This is the case for electric motors, where the power rating refers to the output power at its driving shaft. The input power consumption will evidently be greater
Fluorescent and discharge lamps associated with stabilizing ballasts, are other cases in which the nominal power indicated on the lamp is less than the power consumed by the lamp and its ballast.
Methods of assessing the actual power consumption of motors and lighting appliances are given in Section 3 of this Chapter.
The power demand (kW) is necessary to choose the rated power of a generating set or battery, and where the requirements of a prime mover have to be considered.
For a power supply from a LV public-supply network, or through a MV/LV transformer, the significant quantity is the apparent power in kVA.