What are RCBOs?

The term RCBO stands for Residual Current Breaker with Over-Current protection. RCBOs combine protection against earth leakage currents as well as against overcurrents (overload or short-circuit). Their function might sound like that of an RCD (Residual Current Device) in terms of overcurrent and short-circuit protection, and that is true. So what is the difference between an RCD and RCBO?

An RCBO is designed to combine the functionality of an MCB and RCD to ensure the safe operations of electrical circuits. MCDs are used to provide protection against over-currents and RCDs are created to detect earth leakages. Whereas the RCBO device is used to provide protection against overloads, short circuits, and earth leakage currents.

The purpose of RCBO devices is to provide protection on the electrical circuits to ensure that the electrical circuit is running safely. If the current is unbalanced, it is the RCBO's role to disconnect/break the circuit to prevent potential damage and hazards to the electrical circuit or to the end user.

What does an RCBO protect against?

As the name suggests, RCBOs are designed to protect against two types of faults. The two common faults that can occur within electrical currents are Earth Leakage and Over-Currents.

Earth leakage occurs when there is an accidental break in the circuit which can cause accidents such as electrical shocks. Earth leakages often occur due to poor installation, poor wiring or DIY jobs.

There are two different forms of over-current. The first form is overload which occurs when there are too many electrical applications on one circuit. Overloading the electrical circuit increases the advised capacity and can cause damage to the electrical equipment and power systems which can lead to hazards such as electrical shock, fire, and even explosions.

The second form is a short circuit. A short circuit occurs when there is an abnormal connection between two connections of an electric circuit at different voltages. This can cause damage to the circuit including overheating or a potential fire. As stated before, RCDs are used to protect against earth leakages and MCBs are used to protect against over-current. Whereas the RCBOs are designed to protect against both earth leakages and over-currents.

When is an RCBO used?

RCBOs are installed in many applications that require combined protection against both over currents and earth leakage currents. It is strongly advised to install RCBO to each separate circuit to prevent faults in the other circuits.

The devices are designed to provide protection for households and other similar uses. It is also used to provide protection for the electrical circuit against damage and to prevent any potential dangers for the end user and the property.

The Benefits of RCBOs:

1. RCBOs have many benefits over using individual RCDs and MCBs which include the following:
2. RCBOs are designed as an “All in One” device. The device provides the protection of both an MCB and an RCD which means there is no need to purchase them separately.
3. RCBOs are able to identify faults within the circuit and are able to prevent potential electrical hazards such as electrical shocks.
4. The RCBO will automatically break the electrical circuit when the circuit is unbalanced to reduce electrical shocks and prevent damage to the consumer unit boards. Additionally, RCBOs will trip the single circuit.
5. RCBOs have a short installation time. However, it is advised for an experienced electrician to install the RCBO to ensure smooth and safe installation.
6. RCBOs facilitate safe testing and maintenance of electrical equipment.
7. The device is used to reduce unwanted tripping.
8. RCBOs are used to enhance protection for the electrical device, the end user, and their property.

Are RCBOs mandatory?

Residual Current Devices (RCD) is compulsory to protect the power and light circuits.

According to the 18th edition regulations, RCDs are required for all lighting circuits in domestic properties in the UK market. It is required by law to have RCDs and MCBs installed in your house to protect you, your family, and your house.

RCBOs are not mandatory however, by law you must have RCDs installed in your home. As RCBOs have the functionality of both RCDs and MCBS, it is the preferred option by many electricians for households. It is recommended by the 18th edition of the BS7671 regulations that a test must be carried out on RCDs or RCBOs every six months. The test is used to ensure the effectiveness of the device.

What are the different types of RCBOs?

At Meteor Electrical, we supply GARO’s Type B and Type C devices. We offer a variety of different amp ratings to suit your requirements. These devices are based on their ability to handle surge currents without tripping.

Type B devices are commonly used for domestic applications where the switching surges are low. According to Electrical Magazine, “Type B devices are designed to trip at fault currents of 3-5 times rated current (ln)”.

Whereas Type C devices are suitable for commercial and industrial applications where the electrical supply has a high input current and is designed to trip at 5-10 times ln. Type C devices are advised over Type B in commercial industries to prevent unwanted tripping.

GARO Type B 20 Amp 30mA 1 Module RCBO:

1. Provides protection of RCDs and MCBs in one unit, providing earth leakage, overload and short circuit protection of domestic installations.
2. Residual current breaker with overload protection.
3. Double pole
4. B Curve
5. Test button for periodic testing
6. BS EN 61009
7. RoHS compliant
8. CE approved

GARO Type C 10 Amp 30mA 1 Module RCBO:

1. Type C provides protection from earth leakage, overload, and short circuit for commercial and industrial installations.
2. Residual current breaker with overload protection.
3. Double Pole
4. B Curve
5. Test button for periodic testing
6. BS EN 61009
7. RoHS compliant
8. CE approved

In addition to these, Meteor Electrical offers an extensive variety of consumer units and boards from Garo complete with RCBOs and RCCBs. 

Final Takeaway

Residual current-operated circuit breakers with over-current protection (RCBOs) are installed in circuits of electrical installations to enhance protection in one device. The device is designed to provide protection for the end user against electric shocks and potential fires.

RCBOs are commonly used in modern households to provide protection against overload, short circuits and earth leakage currents. It is advised for electricians to have an RCBO attached to each separate circuit, so a fault in one circuit will not impact the performance of others. Installing RCBOs in your home will provide a safer environment for you and your family.

For more information on purchasing one of our consumer unit boards and RCBOS, send an email at [email protected] or speak to one of our friendly advisors on the live chat!