Paidong Industrial Zone Qiligang,Yueqing City,Zhejiang province,China.
Paidong Industrial Zone Qiligang,Yueqing City,Zhejiang province,China.
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    08 Apr, 2023
    Posted by elcb_admin
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    RCBO Meaning, Application and FAQ

    Meaning of RCBO

    RCBO combines the functions of MCB and RCD, and is an abbreviated expression of “residual current circuit breaker with overload protection”.

    Overcurrent refers to excessive current caused by too many load devices in the circuit or short circuit in the circuit. Residual current, also commonly known as earth leakage, refers to an open circuit caused by an accidental cut of a wire in a circuit or a bad wire.

    The main function of RCBO is to protect against ground fault, overload, and short-circuit current, and to quickly disconnect the current to protect personnel and rear equipment.

    As technology evolves and smart homes continue to iterate, the smart RCBO emerges.A smart RCBO (Residual Current Breaker with Overload) is an advanced version of the traditional RCBO that offers additional features enabled by smart technology integration. This device still performs the primary functions of an RCBO, which include protection against overcurrent (like MCBs) and earth fault currents (like RCDs), ensuring safety from electrical shocks and potential fires due to faults. However, it is enhanced with capabilities that allow for remote monitoring and control, as well as automation and integration with smart home systems.

    What is an RCBO used for?

    An RCBO, or Residual Current Breaker with Overcurrent, is a safety device used in electrical circuits to provide protection against two types of risks: earth fault currents and overcurrents, which include both overload and short circuit currents.
    The residual current function allows the RCBO to monitor the electric current balance between the live (hot) conductors and the neutral conductor. Under normal conditions, the currents are balanced. If an imbalance occurs (e.g., due to a person getting an electric shock or a leakage path to the ground), the RCBO detects it and disconnects the circuit, thereby reducing the risk of injury or death.
    The overcurrent protection safeguards electrical circuits and connected devices from the damages of excessive current flow that may be caused by an overload or fault in the circuit. For example, if a device draws more current than the circuit is designed to handle (overload) or if there is a short circuit, the RCBO will trip and interrupt the power supply to prevent potential damage to the system.
    Overall, an RCBO is used to protect an electrical circuit from the dangers of both earth faults and overcurrents, enhancing the safety of the electrical system in residential, commercial, and industrial settings.

    RCBO Application

    RCBO combines the functions of MCB and RCD and tries to use a single RCBO instead of a combination of MCB and RCD in practical applications.

    smart circuit breaker system

    So far, most household distribution boxes will be equipped with an RCBO to protect household electrical safety. A smart RCBO TOSMR1 product is used in the picture, which provides short-circuit protection, leakage protection, and overload protection. On this basis, the smart RCBO can remotely control and monitor information, greatly improving convenience.

    In industrial applications

    such as factory wiring, business premises such as hotels, and large medical equipment, it is necessary to provide various electrical fault protection. When installing, it is recommended that each individual circuit be installed with RCBO. In the event of circuit failure, the faulty circuit will not affect the normal operation of other circuits. The following are the product catalogs of the two RCBOs.

    Domestic Applications
    – Household Electrical Circuits: In homes, RCBOs are installed to protect individual circuits, such as those for kitchen appliances, heating systems, or lighting circuits. They ensure that in the event of a fault (e.g., a damaged appliance causing a short circuit or a person coming into contact with a live part), the power is quickly cut off, reducing the risk of electrical shocks or fires.
    – Outdoor and Garden Areas: For outdoor sockets, lighting, or pond pumps, RCBOs provide crucial protection, especially given the increased risk of electrical faults due to weather conditions and outside elements.

    Commercial and Public Buildings
    – Office Buildings: RCBOs are used to protect circuits feeding computers, servers, lighting, and HVAC systems, safeguarding against potential fires and ensuring personnel safety.
    – Schools and Hospitals: Given the sensitivity of these environments, RCBOs are critical in protecting the electrical installations against faults, ensuring a safer environment for students, patients, and staff.

    Specialized Environments
    – Data Centers: RCBOs can protect against electrical faults in circuits powering sensitive equipment, preventing data loss and damage to expensive hardware.
    – Marine Applications: On boats and ships, RCBOs are used to protect electrical circuits from saltwater-induced corrosion and potential electrical faults.

    What are RCD, MCB, and RCBO?

    RCD is a residual current device, which prevents people from being shocked when they touch live equipment, or sometimes the circuit is destroyed, the wires are exposed, or the load equipment and circuit fail to cause an electrical fire. RCD can provide corresponding protection.

    MCB is called a miniature circuit breaker, which provides overcurrent protection. When there are too many load devices on the circuit and the current is too large, or the circuit is in a low resistance state to form a short circuit, the MCB will trip to prevent more serious situations from happening to protect the circuit.

    RCBO combines the functions of RCD and MCB, and its compact size is more suitable for places with limited space than the combination of RCD and MCB. The installation time can also be reduced, and it can completely replace the combination of RCD and MCB.

    What are the disadvantages of using an RCBO to protect a circuit?

    While RCBOs provide comprehensive circuit protection and enhance safety, there are some disadvantages to consider when using them:
    1. Cost:
    RCBOs are generally more expensive than separate RCDs and MCBs (miniature circuit breakers). Integrated technology that provides dual protection also results in higher upfront costs.
    2. Installation and Space:
    While RCBOs can save space compared to installing both an RCD and an MCB, they still take up more space on the switchboard than a single MCB. Space can be an issue when retrofitting older switchboards that were not designed for these devices.
    3. Complexity:
    RCBOs add complexity to the electrical system. In situations where multiple RCBOs are used, identifying which one has tripped due to a fault condition can take more time, especially if they are not properly labeled.
    4. Compatibility:
    With a variety of types and ratings available, ensuring compatibility with existing switchboards and systems can be challenging. RCBOs must be carefully selected to match the power needs and safety requirements of the circuits they are protecting.
    5. Nuisance Tripping:
    Given that RCBOs are sensitive devices used to detect current imbalances, they can sometimes trip unnecessarily due to transient conditions or electrical noise, which can be inconvenient.
    Despite these drawbacks, RCBOs are still widely used for circuit protection because they have combined protection features against leakage and overcurrent, which in many applications can offset the potential drawbacks. It is always important to weigh the advantages and disadvantages specific to the building and electrical system environment.

    How to reset RCBO?

    When the RCBO trips, the product switch will be in the down position. Before carrying out the following process, please carefully check whether other safety items have been completed, then wear insulating gloves, and flip the RCBO switch upwards. At this time, you will hear a “click” sound. If it does not trip, Then the RCBO has been reset and started working.

    Under what circumstances is it optimal to use RCBO?

    RCBO is a good choice in the residential house electrical system, where you want the refrigerator or alarm circuit not to be affected by other circuits. In terms of product use, it is recommended that RCBO be connected to a separate circuit to protect important circuits. For other unimportant circuits, it may be better to consider the cost. For the overall safety of residential buildings, money that should not be saved cannot be saved.

    How to install an RCBO?

    Installing an RCBO (Residual Current Breaker with Overload) involves careful attention to electrical safety protocols and should only be carried out by a qualified electrician. Here’s a step-by-step guide on how an electrician might install an RCBO:

    1. Switch off the Main Power: Before starting any work on the electrical panel, it’s essential to ensure that the main power supply is turned off to prevent electric shock. This is typically done at the consumer unit or distribution board.

    2. Prepare the Distribution Board: Open the board and ensure there is appropriate space for the RCBO. If you are replacing an existing circuit breaker, you may need to remove it carefully to make space.

    3. Identify the Circuit: Identify the circuit where the RCBO will be installed. This circuit should be turned off, and you should verify that there is no power using a voltage tester.

    4. Connect the Live Wire: The live wire (often brown or red) coming from the circuit should be connected to the RCBO’s “Load” terminal. Make sure the connection is secure.

    5. Connect the Neutral Wire: There will usually be a neutral bus bar where neutral wires (often blue) are connected. Connect the neutral wire from the circuit to the RCBO’s neutral terminal.

    6. Connect the Earth Wire: The earth wire (often green and yellow) should be properly connected to the earth bar within the distribution board. This is a safety wire and must not be omitted.

    7. Flying Neutral Lead: Some RCBOs come with a pre-attached neutral flying lead that should be connected to the neutral bus bar. Ensure that this is also securely connected.

    8. Mount the RCBO: Securely clip the RCBO onto the DIN rail in the distribution board. Make sure it’s properly engaged so that it won’t come loose.

    9. Test the Installation: Once the RCBO is fully installed, you can restore power to the board and test the operation of the RCBO by using its test button. The RCBO should trip, indicating it is functioning correctly.

    10. Final Checks and Verification: Perform final checks to ensure all connections are proper, the cover of the distribution board is replaced, and that the area is safe.

    11. Documentation: Record the installation in the property’s electrical circuit chart, and if necessary, notify the local government or relevant authorities as per regulations for inspection or record-keeping.

    Please remember this is just an informative guide. Legislation and safety regulations concerning electrical work can vary by country and region. Always ensure that you hire a professional and certified electrician for any electrical installations or modifications in your home or business premises.


    Residual current circuit breaker with overcurrent protection is RCBO. It combines the functions of RCD and MCB. It can completely replace the combination of RCD and MCB to prevent damage caused by a short circuit, residual current, and overload. It can be used in family homes, factories, and commercial applications. Contact Tongou for more information.

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