A consumer unit is defined by BS 7671:2008+A3:2015, the IET Wiring Regulations, as “a particular type of distribution board comprising a type-tested co-ordinated assembly for the control and distribution of electrical energy, principally in domestic premises, incorporating manual means of double-pole isolation on the incoming circuit(s) and an assembly of one or more fuses, circuit-breakers, residual current operated devices, or signalling and other devices proven during the type-test of the assembly as suitable for such use.” A consumer unit may also be known as a consumer control unit or electricity control unit and may often still be referred to as a fuse box (old term).
A consumer unit ordinarily controls and distributes power to electrical accessories and equipment in a dwelling, including circuits for socket-outlets, lighting circuits, cookers, showers and anything else that requires an electrical supply. It is common for modern consumer units either to have:
- individual residual current circuit-breakers with overcurrent protection (RCBOs) for each circuit; or
- a split load system where two or more residual current circuit-breakers (RCCB) each protects a group of circuits. Should one RCCB operate, other circuits would remain live.
Consumer units installed in the UK must also meet the requirements of Regulation 132.12 Accessibility of electrical equipment, e.g. where disabled persons would access the consumer unit in order to reset circuit-breakers, RCCBs or RCBOs.
New regulation 421.1.201
In January 2015, Amendment No 3 to BS 7671:2008 introduced a regulation relating to consumer units. The wording of that regulation is as follows:
421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall:
(i) have their enclosure manufactured from non-combustible material, or
(ii) be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12.
NOTE 1: Ferrous metal, e.g. steel, is deemed to be an example of a non-combustible material.
NOTE 2: The implementation date for this regulation is the 1st January 2016, but does not preclude compliance with the regulation prior to that date.
The implementation date for this new regulation was 1 January 2016.
The intent behind the new regulation was to contain, as far as is reasonably practicable, any fire within the enclosure or cabinet and to minimise the escape of flames.
Find out more
Featured articles and news
Read about RSHP's British Museum extension which has been shortlisted for the 2017 Stirling Prize.
Read our introductory article to building a house extension.
More updates from DCMS about the large-scale testing of cladding systems and the number of buildings affected.
UandI secure resolution to grant planning consent for major new regeneration project.
IHBC article considers how heritage is dealt with when infrastructure schemes are authorised.
It was the tallest structure in the world for 3,800 years, but to this day the exact construction techniques are a mystery.
Shortlist for the industry's most coveted award announced.
Government responds to Mark Farmer's review of industry, rejecting the call for a levy on clients.
Peter Hansford to examine what wider lessons can be learned from the fire.
Every project is subject to uncertainty. How can construction better understand uncertainty for performance improvement?
MAD Architects reveal their designs for a futuristic campus for electric car manufacturer.
Homebuyers could borrow more with better forecasting of energy bills, according to industry consortium's new report.
Read our introductory article on carbon capture and storage.