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A consumer unit is a box of fuses
Fuse (electrical)

In electronics and electrical engineering a fuse is a type of overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows, which breaks the electrical network in which it is connected, thus protecting the circuit's other components from damage due to excessive current....
 or breakers
Circuit breaker

A circuit breaker is an automatically-operated Electricity switch designed to protect an Electrical network from damage caused by Overcurrent or short circuit....
, usually arranged in a single row.






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Fuseboxforwikipedia
Modernconsumerunithager
A consumer unit is a box of fuses
Fuse (electrical)

In electronics and electrical engineering a fuse is a type of overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows, which breaks the electrical network in which it is connected, thus protecting the circuit's other components from damage due to excessive current....
 or breakers
Circuit breaker

A circuit breaker is an automatically-operated Electricity switch designed to protect an Electrical network from damage caused by Overcurrent or short circuit....
, usually arranged in a single row. This is unlike a distribution board
Distribution board

A distribution board is a component of an electricity supply system which divides an electrical power feed into subsidiary Circuit , while providing a protective Fuse or circuit breaker for each circuit, in a common Enclosure ....
 which has multiple rows of fuses or breakers and usually serves two or more locations, which may be split phase
Split phase

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 applications....
, two phase
Two phase

Two-phase electrical power was an early 20th century polyphase system alternating current electric power distribution system. Two circuits were used, with voltage phase s differing by 90 degree s....
, two phases taken from three phase, or three phases.

A consumer unit fitted with just fuses is often referred to as a "fuse box".

Examples


Modern consumer units (picture bottom right) usually use DIN-rail mount breakers. The rail and the shape of the front opening are standardized but the busbar
Busbar

A busbar in electrical power distribution refers to thick strips of copper or aluminium that conduct electricity within a Electric switchboard, distribution board, substation, or other electrical apparatus....
 arrangements are not. Therefore mixing of brands should generally be avoided and where unavoidable care should be taken to ensure that the breaker chosen is a good fit for the busbars.

Generally a "split load" arrangement is used with some circuits protected by the RCD and others not.

The box pictured top-right is a "Wylex standard" fitted with rewirable fuses. These boxes can also be fitted with cartridge fuses or miniature circuit breaker
Circuit breaker

A circuit breaker is an automatically-operated Electricity switch designed to protect an Electrical network from damage caused by Overcurrent or short circuit....
s (MCBs). This type of consumer unit was very popular in Britain
United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
 until 2001 when wiring regulations mandated residual current device (RCD) protection for sockets that could "reasonably be expected to" supply outdoor equipment (BS7671:2001, ISBN 0-86341-373-0). There were a number of similar designs from other manufacturers but the Wylex ones are by far the most commonly encountered and the only ones for which fuseholders/breakers are still commonly available.

RCD protection types


With the introduction of the recent 17th Edition IEE Wiring Regulations Consumer units now in the UK must provide RCD protection to all cables embedded in walls excepting high integrity circuits such as a "Burglar Alarm", "Smoke Alarms" or "Door Bell" etc.

Consumer units have different methods of protecting circuits. A dual split load consumer unit can be arranged as follows:

RCD 1

  • Upstairs Lights,
  • Downstairs Final Ring Main,
  • Garage Sockets,
  • Shower


RCD 2

  • Downstairs Lights,
  • Upstairs Sockets,
  • Cooker,
  • Heating,


By alternating the circuits like this, power will always be present on one floor if either RCD trips out.

Another way to protect circuits under the 17th Edition IEE Wiring Regulations is by fitting Residual Current Circuit Breaker With Overload (RCBOs) to every circuit although this can be a very costly method.

de:Verteiler (Elektroinstallation)