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Consumer Units
Protect your Home
Your consumer unit is the single most important electrical safety device in your Home. It protects you and your family in two important ways.
Electric Shock - It protects the people in your home from electric shock by disconnecting the faulty circuit before the current can hurt anyone.
Fire - It prevents your home's circuits from becoming overloaded and causing a fire.
Consumer units are necessary to protect all Homes from the smallest flat to the largest country house. Although the range of consumer units is substantial there are only four types of units and they all use a combination of the same devices to protect you.
Any one of the four types of consumer units is capable of protecting your home. The choice of which one to use depends on what electrical equipment you have, how you want to separate circuits and budget.
To help you decision making we have outlined below what the various circuit protective devices in your consumer unit do and then the four different types of consumer units that are available.
Learn More
Our advice for most customers is to invest in an industry leading brand - Hager or Wylex.
In most cases High Integrity Consumer units provide the best balance between budget, flexibility and circuit discrimination.
Circuit Protective Devices
Consumer Unit Main Switch
Isolates the supply from the consumer unit to all circuits in your house. It does not however isolate the power from the electricity company to your consumer unit. Therefore opening the consumer unit main switch does not make your consumer unit safe to work on.
RCD - Residual current device
RCDs are a cost effective way to protect a group of circuits. If you accidentally nailed through a cable electricity would flow though you to earth. The RCD detects this 'earth leakage' and isolates the group of circuits before you are harmed. This is called fault protection.
This does mean that one faulty circuit can cause 'nuisance tripping' by shutting down a number of circuits rather than just the faulty one.
MCB - Mini circuit breaker
If your home circuits become overloaded by having too many things on at once the cable can catch fire. MCBs detect overload before it becomes dangerous and isolate just that circuit. This is called overload protection.
18th Edition Wiring regulations require circuits to be protected against overload and fault. A cost effective way of doing this is to protect a group of MCBs (overload protection) with an RCD (fault protection).
RCBO - Residual current breaker & overload
These combine the functions of RCD and MCB in one device. They eliminate the problem of a fault or overload on one circuit nuisance tripping others. They can be used to protect every circuit in your home. However because of their expense they are often used to protect critical circuits for example the supply to your freezer.
SPD - Surge protection devices
SPDs protect your installation and sensitive home electrical equipment from electrical power surges. These happen when switching high power using devices or by lightening strikes near your home. SPDs were previously unnecessary in homes because: we didn't own sensitive equipment (e.g. computers, fire detection, televisions).
We didn't need to switch high power home devices like electric vehicle charging, speed controlled washing machines, ground source heat pumps.
Main switch
This isolates the power from the electricity company to your consumer unit and every circuit. Some older homes do not have a main switch and must gain permission from their electricity company to break the seal and remove the main fuse to isolate their consumer unit.
Four types of consumer unit set up
Complete RCBO consumer unit
Using a consumer unit supplied with a main switch only we can use RCBOs to ensure each circuit has overcurrent and fault protection. This means that should there be an issue with any one circuit in your home none of the others would be effected.
This arrangement is in our view the most complete circuit protection solution and completely removes nuisance tripping. Nonetheless it is the most expensive method and may not fit every budget.
Dual RCD consumer unit
Using a consumer unit supplied with a main switch and two RCDs we populate the system with MCBs at the correct rating for each one of your circuits.
Each RCD provides fault protection for a bank of MCBs. Each MCB provides overcorrect protection for a single circuit.
This is a cost effective way of complying with 18th edition wiring standards and providing overcurrent and fault protection for each circuit.
The downside is that should there be a fault on any one circuit then the RCD will take out a bank of MCBs.
The impact of this can be reduced by for example splitting the lighting and socket circuits between the two RCDs so that should there be a fault on one then only half of the circuits would be out of use.
High integrity consumer unit
These have three neutral bars that provide the facility for three banks of circuits. This means that RCBOs and two banks of MCBs protected by RCDs can be installed on the same unit.
This arrangement allows critical circuits to be electrically separated and individually protected by RCBOs. Less important circuits are protected within the RCD protected banks of MCBs.
This arrangement enables excellent protection at significantly reduced cost. It is particularly useful when there is need for 10+ circuits or where customers wish to future proof their installation in anticipation of extending their property or installing new equipment like electric vehicle chargers.
RCD incomer unit (Garage unit)
These units do not have a main switch. Isolation is achieved by a single RCD that provides fault protection for a 2 - 4 circuits. Each circuit is protected against overcurrent by MCBs.
There is no separation of circuits in this arrangement and consequently if one circuit trips all are lost.
These are rarely used in dwellings but are highly cost effective solution where power is required to a small number of circuits in a garage, shed or workshop.
