Power factor is the name given to the ratio of the real or usable power measured in kilowatts (kW) to the total power supplied measured in kilovolt-amperes (kVA). Loads such as motors, transformers and lighting ballasts will contribute to a reduced power factor. BC Hydro requires that the power factor of the customer's load be maintained above 90%. At a power factor below 100%, BC Hydro must supply additional reactive power, which increases the costs of the electrical system. To cover these additional costs, a surcharge is applied to the customer's bill for electricity in proportion to the amount of additional reactive power required. Power factor can be corrected by installing power factor correction capacitors. When service entrance power factor correction is properly applied, where harmonic tuning is not required, a payback period of two to three years is typical. Adding capacitors will increase the electrical harmonics in the building. Where sensitive electrical equipment is in use, harmonics levels should be reviewed. In most cases, the impact of capicitors on harmonics can be mitigated.