Consumer Unit

The term “consumer unit” is officially defined in the 2018 edition of BS 7671 (IET Wiring Regulations) as follows:

A specific type of distribution board consisting of a type-tested coordinated assembly for controlling and distributing electrical energy, primarily in domestic premises. It includes 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 control devices proven during the type-test of the assembly as suitable for such use.

For many, the consumer unit serves as the contemporary counterpart to a ‘fuse box’ or ‘fuse board’ and serves as the point of origin for all outgoing final circuits.

The evolution of BS 7671 over recent decades has led to substantial growth in the requirements for consumer units, not only in terms of their contents but also in their construction. This has been especially evident in recent years, with an increased focus on fire safety.

The latest version of BS 7671 in 2018 (the 18th Edition) places significant emphasis on ensuring that all equipment housed within a consumer unit, often serving specific individual purposes, is properly considered in terms of its performance alongside other equipment in its vicinity. This includes considerations such as thermal performance, magnetic effects, fixing details and terminations, ability to withstand fault levels, and current carrying capacity.

–ECA

According to housing statistics and the English Housing Survey glossary published by the Department for Levelling Up, Housing, and Communities in 2019, older electrical systems featured individual electrical circuits fed through separate switch and fuse boxes. From the 1960s to the 1980s, fuses were consolidated into a small number of smaller boxes, usually with a front switch controlling all circuits leading to the box. These boxes typically had a cover that was removable to access the fuses inside. From the early 1980s, the newly named consumer unit (some dwellings having 2) provided for the entire dwelling and was designed to accommodate modern safety measures, such as circuit breakers and residual current devices.