Residual Current Breakers with Over-Current (RCBOs) are vital components in ensuring electrical safety in residential and commercial environments. By combining the functionalities of Miniature Circuit Breakers (MCBs) and Residual Current Devices (RCDs), RCBOs (shown below) provide comprehensive protection against two common types of electrical faults.

FuseBox RCBO

MCBs are designed to protect against over-current caused by overload or short circuits. These can occur when an excessive amount of current is drawn through the circuit due to faulty appliances, damaged wiring, or other issues. MCBs monitor the flow of current and trip the circuit when the current exceeds a predetermined threshold, preventing damage to the electrical system and reducing the risk of fire or injury.

RCDs, on the other hand, guard against earth leakage faults that can result from poor wiring, DIY accidents, or damaged insulation. Earth leakage occurs when current unintentionally flows to the earth, creating a potential risk of electric shock or fire. RCDs detect imbalances between the supply and return conductors and promptly disconnect the electricity supply when an imbalance is detected.

RCBOs combine the protective features of both MCBs and RCDs, offering enhanced safety and convenience for homeowners and businesses alike. By monitoring and responding to both overcurrent and earth leakage faults, RCBOs ensure rapid disconnection of electricity in case of dangerous imbalances, significantly reducing the risks associated with electrical accidents. Consequently, RCBOs are a crucial component in modern electrical installations, helping to maintain a safe and reliable power supply.

When to Use an RCBO

RCBOs are recommended or required by wiring regulations in various scenarios to provide enhanced electrical safety and prevent serious issues that could arise without their use. Below are some common instances when an RCBO would be required:

  1. Mission-critical circuits: Installing an RCBO on essential circuits, such as fridge freezers, security systems, fire alarm panels, or tropical fish tanks, is crucial. These appliances require constant power supply, and an RCBO can help prevent nuisance tripping caused by earth leakage faults on other circuits. Without an RCBO, a fault in another part of the system might cause these crucial devices to lose power, leading to food spoilage, security breaches, or harm to living organisms.
  2. Circuits prone to earth leakage: Outdoor lighting, sockets, or appliances are examples of circuits where earth leakage is more likely to occur due to exposure to moisture, dust, or temperature fluctuations. An RCBO offers enhanced protection against earth leakage faults, minimising the risk of electric shock and potential fire hazards.
  3. Areas with a higher risk of electric shock: Bathrooms, kitchens, garages, and utility rooms are examples of areas where water or damp conditions may increase the risk of electric shock. An RCBO can detect even minor earth leakage and disconnect the power supply quickly, reducing the chance of injury.
  4. Circuits with expensive or sensitive equipment: Electronics like computers, home theatres, or lab equipment are vulnerable to electrical disturbances. An RCBO can provide protection against overcurrent and earth leakage, helping to prevent damage to such expensive and sensitive devices.
  5. New installations or renovations: When adding new circuits or updating existing ones, it's essential to comply with the latest wiring regulations. These regulations often require RCBOs for specific circuits, especially in residential buildings, to ensure optimal electrical safety.
  6. To meet insurance requirements: Some insurance companies may require the use of RCBOs in your electrical system to reduce the risk of electrical accidents and fires. Installing RCBOs can help you comply with their requirements and secure coverage for your property.

What to Look for in an RCBO

Key factors affecting RCBO performance and suitability include:

  1. Rated current: The maximum current an RCBO can carry without tripping. This should match the current rating of the protected circuit. Ensuring that the rated current matches the circuit's needs is crucial to avoid unwanted tripping or overload. A mismatched rated current can compromise the safety and efficiency of the entire electrical installation. Ratings range from 6A to 50A.
  2. Rated residual current: The maximum earth leakage current tolerable by the RCBO without tripping. This should be lower than the threshold causing electric shock or fire hazards. The residual current rating is vital for providing adequate protection against possible accidents. A lower residual current rating offers higher protection but may also cause nuisance tripping, while a higher rating might not provide sufficient protection in some cases. The standard rating for an RCBO is 30mA.
  3. Tripping characteristics: The time and current needed for the RCBO to trip in case of over-current or earth leakage. Different tripping characteristics (B or C) depend on the application and load type. Understanding the specific requirements of your electrical system will help you choose the right tripping characteristic for the RCBO. For example, Type B is suitable for most residential and light commercial installation and Type C is used for inductive loads. There’s also a Type D for highly inductive loads such as motors but RCBOs are mainly B or C rated.
  4. RCBO Types: Type A RCBOs are used to detect AC (Alternating Current) and pulsating DC (Direct Current) components. Type AC RCBOs are used for general purpose on AC (Alternating Current) only circuits. The FuseBox Mini RCBOs provide Type A and Type AC protection in one, so if in doubt select one of these, they're also more compact in design which saves additional space for wiring.
  5. Breaking capacity: The maximum short circuit current safely interruptible by the RCBO. This should be higher than the prospective short circuit current of the protected circuit. A high breaking capacity ensures that the RCBO can safely interrupt even substantial short circuit currents, preventing severe damages and hazards. Make sure to choose an RCBO with a breaking capacity that meets or exceeds the demands of your electrical system. The standard breaking capacity rating for an RCBO is 6kA and some are rated at 10kA.
  6. Physical size: The dimensions and shape of the RCBO and how it fits into the consumer unit or distribution board. Some RCBOs are more compact, saving space in crowded installations. The physical size is important, particularly in situations with limited space or numerous devices in the consumer unit or distribution board. A compact RCBO allows for easier installation and ensures proper organisation of the electrical system.

When selecting an RCBO, consider these factors to ensure optimal performance and suitability for your specific electrical installation. Each aspect is essential, but the importance of each might vary depending on the individual circumstances and requirements of your electrical system. Taking the time to understand and evaluate these factors will help you make the right choice for a safe and efficient RCBO installation.

How to Choose an RCBO Brand

When comparing different RCBO brands, it's essential to consider various factors to ensure you're making an informed decision. Understanding the importance of each criterion will help you choose an RCBO that meets your requirements and offers the best value for your money. Here are some detailed considerations for each factor:


  • Reliability and durability: A high-quality RCBO should provide consistent performance and last for an extended period without malfunctioning. Look for products made from robust materials that can withstand wear and tear, and are less likely to develop faults over time.
  • Compliance with standards and certifications: Ensure the RCBO you select complies with relevant international and local standards, such as IEC/EN 61009. Compliance with these standards indicates that the product meets specific safety and performance requirements.
  • Manufacturer reputation: Choose RCBOs from established manufacturers with a solid reputation for producing reliable and safe electrical products. Well-known brands often have more resources for research and development, leading to better products and a higher level of quality assurance.


  • Cost-effectiveness: Evaluate the price against the features, quality, and performance of the RCBO. A cheaper product might seem like a bargain, but it could also compromise safety and reliability.
  • Value for money: Consider the total cost of ownership, including the purchase price, installation costs, and potential savings from reduced energy consumption or minimised damage to appliances.
  • Warranty and after-sales service: A good warranty indicates that the manufacturer has confidence in their product. Additionally, excellent after-sales support can be invaluable if you encounter issues with your RCBO.


  • Online or offline purchase: Determine if your preferred RCBO brand is easily available through online retailers, local distributors, or electrical supply stores. Factor in delivery times and shipping costs when purchasing online.
  • Stock availability: Ensure the brand you choose has a sufficient supply of the specific RCBO model you require. If a particular model is scarce or discontinued, you might face challenges if you need a replacement or additional units in the future.


  • Consumer units or distribution boards: Verify that the RCBO you select is compatible with your existing consumer unit or distribution board. Incompatibility may require additional modifications or even the replacement of the entire consumer unit, increasing costs and complexity.
  • Other electrical devices: Ensure the RCBO is suitable for the devices and appliances you intend to connect to the protected circuit. For instance, some RCBOs may not work correctly with specific types of loads or sensitive equipment.


  • Customer feedback: Read reviews and ratings from other users who have experience with the RCBO brand and model you are considering. Look for patterns in feedback, such as common issues, excellent performance, or helpful customer support.
  • Expert opinions: Consult professional electricians, electrical engineers, or industry experts for their recommendations and insights. They often have hands-on experience with a wide range of products and can provide valuable advice.

Top RCBO Brands

Some popular and reputable RCBO brands on the market include:

Schneider Electric: A global leader in energy management and automation solutions, Schneider Electric offers a wide range of RCBOs with varying rated currents, residual currents, and tripping characteristics. Their RCBOs feature a compact and modular design, making installation and maintenance easy. Additional features include a test button and an indication window for straightforward status verification. However, Schneider Electric products may be more expensive and incompatible with older consumer units or distribution boards.

FuseBoxAn innovative UK brand specialising in circuit protection products, FuseBox offers RCBOs that provide protection against overcurrent and earth leakage for single-pole circuits. Their products come with various tripping characteristics to suit different applications. Known for their solid construction and reliable performance, FuseBox RCBOs also feature a test button and a green indicator for effortless status verification. Some of our recommended FuseBox products are:

Fusebox mini RCBO

RolecA leading provider of electrical solutions, Rolec manufactures RCBOs that offer reliable protection against overcurrent and earth leakage. Their products come in various rated currents, residual currents, and tripping characteristics to suit different applications. Rolec RCBOs are known for their high-quality materials, durability, and safety features such as a test button and indication window. However, Rolec products may be more expensive, and compatibility with certain consumer units or distribution boards may be limited.

Elucian from Click Scolmore: A renowned UK manufacturer of wiring accessories and lighting products, Click Scolmore offers a range of RCBOs designed for various applications. Their products feature a user-friendly design, easy installation, and a test button for convenient status verification. Click Scolmore’s Elucian brand of circuit protection is fairly new to the industry. The don’t have the brand name of Schneider or the alluring price point of FuseBox.

Chint: An international electrical equipment manufacturer, Chint offers a wide range of RCBOs with different rated currents, residual currents, and tripping characteristics. Their RCBOs are known for their quality, reliability, and affordability. Chint RCBOs feature a simple design, easy installation, a test button, and an indication window for quick status checks. Chint RCBOs are more expensive when compared to other brands.

Order Circuit Protection Like a Pro

Professional installers who install consumer units regularly tend to order them with an SPD (Surge Protection Device) and main switch. What about the RCD incomer? This isn't needed because pro installers use RCBOs as their outgoing devices. This way every circuit is individually RCD protected which provides a safer installation, it doesn't put too much load on the RCD incomer and if a circuit trips it doesn't trip the entire board. The FuseBox surge protected consumer units are made from a robust metal enclosure and are available at a very affordable price. They're 18th Edition Compliant and provide comprehensive circuit protection.

Fusebox consumer unit with surge

Why Buy From Expert Electrical?

Expert Electrical Supplies Ltd is a trusted and experienced electrical wholesaler specialising in industrial electrical equipment. Established in 2004, the company has built a strong reputation for reliability, efficiency, and quality products. Here are some key reasons why you should choose Expert Electrical:

  • Founded by industry professionals with decades of experience, Expert Electrical is dedicated to meeting your industrial electrical needs.
  • A one-stop-shop, offering a wide range of products from circuit protection equipment to cable and lighting solutions for domestic and commercial sectors.
  • Part of Fegime, the largest electrical wholesaler buying group in Europe, enabling them to provide competitive pricing on high-quality products.
  • Customer-focused approach, with transparent communication, efficient service, and commitment to resolving issues quickly.
  • Bulk order discounts and support available for customers looking to reduce their spend or establish a consistent supply chain.

Key Features

  • Transparent and reliable service
  • Wide range of products
  • Competitive pricing
  • Excellent customer support
  • Experienced professionals

To discuss your requirements, get in touch with Expert Electrical at 01706 860011 or email: [email protected]. We're here to provide you with a long-term, consistent supply chain of electrical products at the right price and delivered when you need them.