Commercial Buildings include multi-storey buildings, such as office towers, apartments, condominiums, hotels and hospitals, and low-rise structures such as schools, senior citizens' homes, shopping complexes, airports and railroad stations. The wire and cable chosen will vary considerably depending on the size of the facility.

For multi-storey buildings, electrical power from the electrical distribution system, frequently enters a transformer room or electrical room. Consider for example a 69-storey office tower. Power at 13.8 kV enters two electrical rooms, one located underground and the other on the 68th floor. Transformers step-down the power to 600 and 347 volts for large equipment, and to 220 and 110 volts for the general power and lighting requirements of the internal distribution systems. There are approximately 200 transformers sized from 2,000 kVA downwards, and the electrical circuits required about 1,300 km (800 miles) of copper wire and cable.

Modern commercial buildings are provided with excellent lighting, and convenient power receptacles. In addition, work areas are provided with telephone and communications data positions. In an office tower, the wiring for telephones can reach vast proportions. In one example, the office tower has over 8,000 telephones, served by more than 97,000 metres (about 318,000 feet) of 2,700-pair (5,400 conductors) telephone cable, this being a total of about 9.45 million metres (nearly 31 million feet) of copper conductor.

Typically, for computers, a copper riser cable extends vertically, connecting with a telecommunications closet on each floor. Here, connections are made and circuits spread out to the work areas, the cables usually being UTP (Unshielded Twisted Pair Horizontal Cables). The term 'horizontal' is used because normally the cable in this part of the system runs along floors or ceiling.

In commercial buildings many things happen automatically, such as heating and air conditioning, ventilation, and emergency lighting and voice systems. While a fire alarm is an important item in any building, it is particularly important in those handling larger numbers of people. The activation and control of these systems rely on Low Voltage Cables.

An example of a shopping complex is the Toronto Eaton Centre, which includes a 9-storey retail store, a 3-storey covered mall containing about 100 stores, and a 26-storey tower. The electrical distribution for illumination, air conditioning, elevators and escalators, involves close to 28,000 metres (about 93,000 feet) of 250, 350 and 500 kcmil, single-copper-conductor, 600-volt Aluminum Sheathed Cables.