A distribution board (known in the United States as a circuit breaker panel or just breaker panel) is a mounting enclosure for multiple electrical circuit breakers. These are generally placed in two rows. Small single-phase boxes, with the breakers in just one row, are known as consumer units. Distribution boards are typically found in central locations inside buildings and often serve as the point at which electricity is distributed within a building. (For this reason, circuit breakers usually also function as switches to manually deactivate electrical circuits within a building when wiring is being serviced.) American breaker panels commonly have many live parts exposed with the lid off. British distribution boards by contrast generally have live parts enclosed to IP20, even with the lid off. This makes testing and live working much safer, especially given the voltage (415 volts) present in such boards. Image File history File links Download high resolution version (510x640, 73 KB)photo of UK Electrical Distribution Board photo taken by me and hereby licensed as follows. ... A circuit breaker is a piece of equipment which is designed to protect an electrical apparatus from damage caused by overload or short circuit. ... Wylex standard consumer unit fitted with rewirable fuses A consumer unit is a box of fuses or breakers usually arranged in a single row. ... Lightning strikes during a night-time thunderstorm. ... The volt (symbol: V) is the SI derived unit of electric potential difference. ...

Breaker arrangement

Breakers are usually arranged in two columns. In a US-style board, breaker positions are numbered left-to-right, along each row from top to bottom, as shown below:

These breakers cycle through two or three phases, labelled as X, Y, and Z in the above diagram. This numbering system is universal across various competing manufacturers of breaker panels.

In a UK-style board, breaker positions are numbered top to bottom in the left hand column, then top to bottom in the right column. Each number is used to label one position on each phase, as below. It remains to be seen how the new wiring colours recently introduced in the UK will affect this labelling. The accepted standard for electrical wiring in the UK is the IEE wiring regulations, formally known as BS 7671:2004 and colloquially referred to as the regs. These are created by a non-governmental body and in themselves are only recommended practice. ...

In both labelling styles the reason for the alternating pattern of phases is to allow for common trip breakers to have one pole on each phase. Ideally the number of rows is a multiple of 3, so there are the same number of breakers on each leg of the three-phase supply, but this is not always the case; some three-phase panels have 40 or 50 breaker slots, rather than 42 and 48.

In North America it is common to wire large heating equipment line-to-line. This takes two slots in the panel (two-pole) and gives a voltage of 240V if the supply system is split phase and 208V if the supply system is three phase. This practice is much less common in countries that use a higher line-neutral voltage. Large motors, air conditioners, subpanels, etc., are typically three-phase (where available). Therefore a three-pole breaker is needed which takes three slots in the breaker panel. A split phase electricity distribution system is a 3-wire single-phase distribution system, commonly used in North America for single-family residential and light commercial (up to about 100 kVA) applications. ... Three-phase systems have 3 waveforms (usually carrying power) that are 2π/3 radians (120°,1/3 of a cycle) offset in time. ...

Inside a North American panel

Inside a typical American breaker panel, located in a front living room. The three lugs at the bottom are the three "hot" ("live") wires. A fourth white (neutral) wire (not shown) comes in at the top of the panel to a neutral bar. This breaker panel has 12 positions, the bottom six of which (shown in the picture) are taken up by two three-pole breakers (position 7, 9, 11 at left, and 8, 10, 12 at right) that each supply a separate three-phase circuit. American panels frequently have live parts exposed when the cover is removed, in contrast to British panels. Download high resolution version (1024x756, 97 KB)Inside view of 12 position breakerpanel on Level 4. ... 1500 amp busbars within a power distribution rack for a large building A busbar (often pronounced buzz bar) refers in electrical power distribution to thick strips of Copper or other material that conduct electricity around a switchboard or distribution board. ...

Inside a UK distribution board

Inside a typical 12-position UK distribution panel. The three incoming phase wires connect to the busbars via an isolator switch in the centre of the panel. The incoming neutral connects to the neutral busbar at the centre right of the board, which is in turn connected to the neutral busbar at the top left side of the board. The incoming earth wire connects to the earth busbar at the centre left side of the panel, which is in turn connected to the earth busbar at the top right of the board. The cover has been removed from the neutral bar at the right of the board; the neutral bar on the left side has its cover in place. Image File history File links Download high resolution version (510x640, 73 KB)photo of UK Electrical Distribution Board photo taken by me and hereby licensed as follows. ... 1500 amp busbars within a power distribution rack for a large building A busbar (often pronounced buzz bar) refers in electrical power distribution to thick strips of Copper or other material that conduct electricity around a switchboard or distribution board. ...

Down the left side of the phase busbars are two two-pole RCDOs and two single-pole breakers, one unused. Down the right side of the busbars are a single-pole breaker, a two-pole RCDO and a three-pole breaker. In electrical installations, residual current devices (RCD) or residual current circuit breakers (RCCB) are circuit breakers that operate to disconnect their circuit whenever they detect that current leaking out of the circuit (such as current leaking to earth through a ground fault) exceeds safety limits. ...

The two-pole RCDOs in the picture are not connected across two phases, but have supply-side neutral connections exiting behind the phase busbars.

It is likely that the manufacturer produces 18- and 24-position versions of this panel using the same chassis which explains why there appears to be so much unused space.

Manufacturer differences

Most of the time, the panel and the breakers inserted into it must both be from the same company. Each company has one or more "systems", or kinds of breaker panels, that only accept breakers of that type. In Europe this is still the case despite the adoption of a standard DIN rail for mounting and a standard cut-out shape as the positions of the busbar connections are not standardised. A DIN-rail mounted telephone modem. ...

It is commonly known in North America that Siemens and Cutler Hammer panels and breakers of the type shown in the above and below picture illustrations are interchangeable. Therefore, these two types of breaker panels have gained widespread acceptance as a "standard". The two panels shown (one Siemens, and the other Cutler Hammer) seem to fit GOULD Type QP, ITE type QT, Cutler Hammer Type BR, and Siemens breakers. World map showing location of North America A satellite composite image of North America North America is a continent in the northern hemisphere, bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west... Company headquarters in Munich, Germany Siemens AG NYSE: SI is the worlds largest electronics company. ...

Location

For reasons of aesthetics and security, circuit breaker panels are often placed in out-of-the-way closets, attics, garages, or basements, but sometimes they are also featured as part of the aesthetic elements of a building (as an art installation, for example) or where they can be easily accessed. Aesthetics (also esthetics) is the philosophy of beauty and art. ... Categories: Stub | Home ... Meanings for the term include: Attic (always capitalised) is an adjective for something or someone coming from Attica or Athens. ... Garage has several meanings: Look up Garage on Wiktionary, the free dictionary In connection with vehicles, a garage has the following meanings: A building attached to or on the grounds of a residence for storing an automobile (UK: car) A garage that is open on at least 2 sides is... A basement is a storey of a building that is either completely or partially below the ground floor. ...

Larger buildings or facilities with high electric power demand may have multiple circuit breaker panels. In this case, the panels are often indicated by letters of the alphabet. One case is The Decon Gallery, a modern building in downtown Toronto, which has 11 breaker panels designated "A", "B", "C", "D", and so on. A backstage outlet is therefore labeled "C27". In many such buildings, each outlet is on its own circuit breaker, and the outlets are labelled in the above specified manner to facilitate easy location of which breaker to shut off for servicing, rewiring, or the like. Transmission lines in Lund, Sweden Electric power, often known as power or electricity, involves the production and delivery of electrical energy in sufficient quantities to operate domestic appliances, office equipment, industrial machinery and provide sufficient energy for both domestic and commercial lighting, heating, cooking and industrial processes. ... }|135px|City of Toronto, Ontario Official Flag]]|Coat Image=[[Image:{{{Coat Image}}}|135px|City of Toronto, Ontario Coat of Arms]]}} {{Canadian City/Disable Field={{{Disable Motto Link}}}}} Motto: Diversity Our Strength {{Canadian City/Location Image is:{{{Location Image Type}}}|[[Image:{{{Location Image}}}|thumbnail|center|250px|City of Toronto, Ontario, Canada...

Distribution boards may be surface-mounted on a wall or may be sunk in to the wall. The former arrangement allows for easier alteration or addition to wiring at a later date, but the latter arrangement may look neater, particularly in a residential situation. The other problem with recessing a distribution board into a wall is that if the wall is solid a lot of brick or block may need to be removed - for this reason recessed boards are generally only fitted on new-build projects when the required space can be built in to the wall.

Mobile operation

Sometimes it is desired to have a portable breaker panel, for example, for special events. In this case, a breaker panel is mounted to a board, together with various sockets. These are common in the movie industry, and are sometimes referred to as "Dief boxes" because John Diefenbaker tripped over one when they began to go into widespread use. The American one pictured at the right has a cord with an L21-30 plug to supply power. Power leaves the board through four three-phase circuits: three 15-ampere circuits; and one 20A circuit. The 15A circuits each go to a triplex-box. The 20A circuit goes to an L21-20 receptacle, and one leg of it goes to a 20A duplex receptacle shown at the upper left. The neon nightlights on the upper right triplex box are to show the phase sequence.
Download high resolution version (1024x1485, 97 KB)3phase 12position portable breakerpanel I took this picture from near level 4, looking up into the mech room. ... The Right Honourable John George Diefenbaker, PC , LL.B , MA , BA (September 18, 1895 – August 16, 1979) was the thirteenth Prime Minister of Canada (1957 – 1963). ... Industrial power plug is used here to refer to those power connectors that, unlike ordinary mains power plugs, are not used for the average domestic appliance but rather for more heavy-duty applications such as arc welders, cranes, cinemas, large cooking ranges, etc. ... In physics, the ampere (symbol: A, often informally abbreviated to amp) is the SI base unit used to measure electrical currents. ... Industrial power plug is used here to refer to those power connectors that, unlike ordinary mains power plugs, are not used for the average domestic appliance but rather for more heavy-duty applications such as arc welders, cranes, cinemas, large cooking ranges, etc. ...

See also

• consumer unit
• Electric switchboard