The requirements of the planning and execution of electrical works of an ordinary building having ground plus one or two floors housing are quite different from those of a multistoried or high rise building. A building is classified as ‘High Rise’, if it has more than Four floors (Ground + 3 Floors) or height more than 15 meters. It can be regarded as a miniature township requiring entire range of civic services such as electric power from the electricity board, standby / emergency power from diesel generator, water supplies for various applications, fire fighting system, elevator services, sanitation, recreation facilities, swimming pool, lighting for apartments as well as common areas etc.
These systems are known as single-phase, two wire systems (1-ph, 2w). Common appliances such as light bulbs, fridges, TVs, press irons, etc., have a small enough line load to require a single phase electrical feed.
Apartments and Condos, usually would use two phases for each unit so they would have two live wires with 208 volts between them and 120 volts between each line and a neutral, allowing the unit to power receptacles and lighting at 120 Volts and the range at 208 volts.
All types of machinery that use large motors to operate, including central AC units, pumps, air handling units, garbage compactors, elevators, and snow melting systems run on three phase systems and require three-phase electrical meters.
This provides the installer with a single model that can literally be installed in any type of low voltage installation, whether residential, commercial or industrial, to the user the flexibility of changing it from one circuit to another at a later