An electric switchboard is a device that distributes

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...

from one or more sources of supply to several smaller load circuits. It is an assembly of one or more panels, each of which contains switching devices for the protection and control of circuits fed from the switchboard. Several manufacturers make switchboards used in industry, commercial buildings, telecommunication facilities, oil and gas plants, data centers, health care, and other buildings, and onboard large ships. A switchboard is divided into different interconnected sections, generally consisting of a main section and a distribution section. These two sections are sometimes replaced by a combination section, which is a section that can fulfill the roles of both aforementioned sections. Switchboards can also sometimes come with an auxiliary section that is used to house devices that cannot be housed in the same section as other devices.

Definition

The U.S.

National Electrical Code The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Prote ...

(NEC) defines a switchboard as "a large single panel, frame, or assembly of panels on which are mounted, on the face, back, or both, switches, over-current and other protective devices,

buses A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...

, and usually instruments". The role of a switchboard is to allow the division of the current supplied to the switchboard into smaller currents for further distribution and to provide switching, current protection and (possibly) metering for those various currents. In general, switchboards may distribute power to transformers, panelboards, control equipment, and, ultimately, to individual system loads.

Components

Inside a switchboard there will be one or more

busbar In electric power distribution, a busbar (also bus bar) is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution. They are also used to connect high volt ...

s. These are flat strips of copper or aluminum, to which the switchgear is connected. Busbars carry large

current Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (stre ...

s through the switchboard, and are supported by insulators. Bare busbars are common, but many types are now manufactured with an insulating cover on the bars, leaving only connection points exposed. In a modern switchboard, the operator is protected from

electrical injury Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce a ...

by metal-enclosed circuit breakers, switches, and

fuses Fuse or FUSE may refer to: Devices * Fuse (electrical), a device used in electrical systems to protect against excessive current ** Fuse (automotive), a class of fuses for vehicles * Fuse (hydraulic), a device used in hydraulic systems to protec ...

. There may also be instruments and controls for the supply of electricity to the switchboard. For example, a switchboard for a bank of

electrical generator In electricity generation, a generator is a device that converts motive power (mechanical energy) or fuel-based power (chemical energy) into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, gas ...

s, especially

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

would have control of AC power and load sharing, and instruments for frequency, voltage, current, and energy, with perhaps a

synchroscope In AC electrical power systems, a synchroscope is a device that indicates the degree to which two systems ( generators or power networks) are synchronized with each other.Terrell Croft, Wilford Summers (ed.), ''American Electricians' Handbook E ...

. The amount of power going into a switchboard must always be substantially equal to the power going out to the loads ( less the losses in internal conductors and consumption by internal devices such as pilot lamps, space heaters, or others).

References

{{Reflist Electrical components Switches de:Schaltschrank