Everything You Need To Know About Consumers Unit And Its Parts Revealed

consumers unit


Electrical safety is very important in industrial and domestic circuits. A consumer unit is a complete electrical protection package installed inside the building. Consumer unit is also known as “Fuse Box” most commonly. The primary purpose of the consumer unit is to provide complete control of the electrical supply inside the home, office, or commercial building. Even though consumers unit is most commonly used in our houses, we still do not know about them completely. This guide will explain to you about the consumer unit. So, let’s get start exploring the consumers unit.

Consumers unit

A consumers unit is a most commonly used and essential electrical device. It protects human and electrical appliances from electrical hazards like overheating, overflowing current and electrical shocks.

The size and structure of the consumer unit are highly dependent on the size of the building and the type of protection you want from it.

Parts of a consumers unit

The consumer unit comprises many things, called the parts of the consumers unit. Following are the brief detail about the different parts of the consumer’s unit or fuse box.


The body is the main part of any consumers unit, and the purpose of the body is to give proper support and protection to the devices that are installed inside of it. The body of the consumers unit mainly comes in the following materials:

  • Metal (Steel)
  • Plastic
  • Wood

In the early days, consumers unit body was made with wood, but wooden boxes are obsolete now due to its drawbacks. The professional recommended that the body of any consumer unit must be made with any non-flammable material. So, the team could be saved from fire if overheated consumers.

Main Switch

The main switch is the most important component installed inside any consumer unit. The main switch is the first Device used to control the main supply; if you want to cut off the overall supply on the premises, then you switch off the main switch in case of emergency, and while the electrician has to work on the electrical system then main switch help to cut off all the power that is flowing inside of any building.

Circuit Breaker

After the main switch, the second protection device installed in the consumer unit is called a circuit breaker. Sometimes circuit breakers are called “Mini Circuit Breakers” (MCB). The main purpose of any circuit breaker is to turn off automatically when any current start flowing in the electrical circuit. The circuit breaker could be automatically turned off when the following conditions occur in the system:

  • The circuit breaker will cut off the main supply when an overload of power flows through it.
  • The second reason is turning off the circuit breaker in the flow of over current.

The circuit breaker is rated according to different ampere values. Six amperes to fifty-ampere rating circuit breakers are enough for domestic use. However, the rating of the commercial circuit breaker is available up to one hundred and twenty-five amperage rating. When the circuit breaker turns off the supply due to an over-current overpowering, you can turn it “ON” after clearing the fault in the system. There is no need to replace the circuit breaker once it automatically turns off.

Residual current Device

The next Device used in the consumer unit is called residual current, commonly known as RCD. RCDs are used in any consumer unit to protect humans from electrical shock. The residual current Device continuously monitors the current flowing through it. If the outgoing current increases, then incoming (Feedback) current, then the RCD will trip off and cut off the main supply.

How can RCDs protect you from electrical shock?

If a human accidentally touches a bare wire, then extra current flow through the human. In this case, RCD detects that the value of the outgoing current is higher than the feedback current. As a result, the main supply turns off, and humans will be saved from electrical shock. Once the fault is apparent, you can switch on the RCD-like circuit breaker again.

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Testing of RCD

You should note about RCDs are that you must test your RCD every three months. The testing of RCD will confirm that it is working properly. On the top left corner is a red button on the body of RCD. Once you press the red button, your RCD works correctly if the man supply turns off. If nothing has happened by pressing the red button, it means your RCD is faulted. It would help if you immediately replaced faulty RCDs.

A metal bar or Din Rail

Din rail or metal bar is also a part of the main body of the consumers unit, which supports the main switch, RCDs, Circuit Breakers, and other protection devices. Din rail is mounted in the center of the main body of any consumers unit.

Connector for cables

On the main body of the consumers unit, multiple connectors are present, which are used to connect with the consumers unit. The main supply is provided to the consumers unit, and connections of different appliances have also been taken from these connections. Circuit cables or bus bars are making these connections. Earth cables and bonding conductors are also attached to these connectors.

Incomer consumer units: what are they?

The ‘RCD Incomer’ consumers unit is a special type of protection device commonly found in workshops, garages, garden offices, and sheds that do not require many circuits to operate. Consumers units without a ‘Main Switch’ are differentiated from other types.


So, after reading this guide, you have to know about the consumers unit and its different parts. To protect the electrical system, you must install all the protection devices inside of consumer unit. The consumers unit will ensure electrical safety in any building. If you are going to make a new house or not install a consumer unit in your current house, do not forget the installation of the consumer unit on priority bases.

FAQs (Frequently Asked Questions)