Domestic Consumer Units and Circuit Protection Devices – A Glossary

Consumer Units, Circuit Protection Devices and Accessories – A Glossary

Consumer Unit

A client unit is {the electrical} software used to distribute energy all over a home living. Acting as a security software, protective in opposition to damage via electric surprise, a client unit homes coverage units which additionally give protection to family home equipment from overload.

A client unit’s first serve as is the organisation {of electrical} ‘circuits’, such that the other ways by which we use electrical energy all over the house is also safely and extra simply controlled. A normal home set up, for instance can have the next circuits: Ring primary for energy sockets and pieces like washing machines and TVs, Lighting, smoke alarms, cooker, bathe and so on.

Main Switch

This is the ‘Double Module’ software which sits at the a ways proper hand aspect of a client. It typically has a large crimson bar transfer and acts to isolate all of the board. This signifies that via guide operation it might reduce energy to each circuit within the set up. Main Switches are nearly all the time rated at 100 amp, permitting it to isolate an set up which draws not more than 100 amps in general throughout all circuits.


Mini Circuit Breaker. An MCB protects its circuit in opposition to overload. When for instance a bulb blows on a lights circuit the MCB cuts the ability to the that circuit, thus protective the opposite lighting. No different circuits at the shopper unit were affected. An MCB does no longer give protection to other people in opposition to electrical surprise.


Residual Current Devices give protection to a couple of circuits in opposition to earth leakage. This is an important serve as of a client unit as it’s earth leakage which reasons electric surprise. RCDs measure the volume of electrical energy flowing into the shopper unit in opposition to the volume flowing out. When it detects an imbalance between the 2 it cuts the electrical energy provide to the financial institution of circuits it is protective.

It must be famous that which means that a fault on one circuit will lead to a slicing of the ability to every other circuit secure via that RCD. For instance an RCD might give protection to the hoop primary and indoor and out of doors lights circuits. In this example a fault at the out of doors lights circuit will knock out the indoor lights and all energy sockets.

It is because of this that the 17th Edition Regulations call for ‘Division of Circuits’ to keep away from ‘Nuisance Tripping’


Residual Current Breaker with Overload (RCBO). This artful software combines the capability of an MCB and RCD and subsequently lets in for impartial coverage on particular person circuits in opposition to each overload and earth leakage.

Din Rail

The mounting rail upon which can be fitted the Main Switch, RCDs, MCBs and RCBOs.


The software which connects electrically the Main Switch, RCDs, MCBs and RCBOs.

Neutral Bar

The terminal bar which accepts all of the impartial wires from the RCBOs and MCBs.