An electrical closet or electrical room is a designated chamber that contains the central hub and control interface of a building's electrical circuits. Electrical closets vary in size and number depending on the dimensions and layout of the structure that they service. Houses and other relatively small buildings may not even need an electrical closet. These chambers are more common in sprawling structures -- like schools, factories and warehouses -- with high square footage and multiple stories.
Electrical closets provide secure and accessible storage space for sensitive, and potentially dangerous, electrical equipment. Large buildings have complex, high-voltage electrical systems, so a separate electrical room makes operating and servicing circuitry safer and more convenient. Houses and apartments may also have electrical closets, although the circuitry interface is often limited to a simple panel of fuses or breakers.
Size and Amount
The dimensions of an electrical closet, and the total number of electrical closets required to service a facility, depends on the size of the structure. A single-story structure of 20,000 square feet or less often requires only one, relatively small electrical room of about 400 square feet, according to Architectural Engineering Design Group. Large buildings with more square footage or multiple stories often require a larger primary electrical closet as well as additional auxiliary chambers. Auxiliary closets are particularly useful in sprawling structures that are separated into distinct units or wings.
Design and Layout
The contents and layout of an electrical closet depends on the particular needs and circuits of the structure that it services. Some closets contain networking cables, routers and modems as well as electrical conduits. Transformers, which translate the powerful currents of utility wires into usable voltage levels, and user interface panels are found in most electrical closets. The user interface usually provides direct controls for the entire building's power in case of emergencies or maintenance, as well as controls for certain conduits.
Rules and Regulations
Electrical closets often house dangerous equipment and high-voltage currents, so they are subject to federal and state regulations. There must be at least 3 feet of open space around any equipment serving 120 to 600 volts, according to the United States Office of Compliance. The doors of electrical rooms should open outwards, to allow the occupants to safely and quickly evacuate in case of emergency. The room should also be insulated to prevent flooding, which could greatly increase the risk of electrocution, and fire.