An electrical system, within the context of a building, is a network of conductors and equipment designed to carry, distribute and convert electrical power safely from the point of delivery or generation to the various loads around the building that consume the electrical energy. The vast majority of electrical systems used in buildings in the UK operate at 230V single phase alternating current (AC) or 400V 3 phase, at a frequency of 50Hz. These networks are often referred to as low voltage (LV) networks. This system is also referred to as mains electricity. Larger installations may operate at higher voltages, often with 11kV supplies or feeders at the origin of the installation. These networks are referred to as high voltage (HV) networks. Power conversion from 11kV networks down to the 230V-400V range is usually undertaken via transformers in a substation.