The main types of circuit breakers used in low-voltage distribution include miniature circuit breakers (MCBs), molded case circuit breakers (MCCBs) and residual-current devices such as RCCBs and RCBOs. They are not interchangeable. MCBs and MCCBs are selected for overcurrent protection in different circuit roles, an RCCB provides residual-current protection without integral overcurrent protection, and an RCBO combines residual-current and overcurrent protection in one device.
This guide focuses on the low-voltage product families that OOHMAGE supplies. It explains what each device does, where it may fit in a protection arrangement and which details a buyer should confirm before discussing a model or quotation. It does not cover medium-voltage or high-voltage breaker families that fall outside this product scope.
This is a product-family classification guide, not a project-specific circuit-breaker selection study. It does not replace fault-current calculations, coordination work, local-code review or confirmation against the selected model documentation.
For many low-voltage panels and distribution projects, the practical starting list is:
Surge protective devices are frequently discussed beside these products, but an SPD is not a circuit breaker. It serves a different role by limiting surge voltage and diverting surge current within a coordinated protection arrangement.
These names identify product families. They do not by themselves determine the final model, rating, pole configuration, breaking capacity or suitability for a particular installation. Selection still depends on the circuit role, system data, fault conditions, local requirements and the published parameters of the chosen series.
Long lists of breaker names can make selection harder because they mix several classification methods. A clearer approach is to ask three separate questions.
Overcurrent protection responds to overload and short-circuit conditions according to the design and ratings of the selected device. Residual-current protection responds to an imbalance associated with current flowing through an unintended path. Some devices provide one function; others combine both.
This distinction separates RCCBs from RCBOs. In IEC terminology, an RCCB is a residual-current operated circuit breaker without integral overcurrent protection, while an RCBO includes integral overcurrent protection. The surrounding circuit arrangement must reflect that difference.
A branch circuit, feeder, distribution incomer and machine circuit do not automatically use the same breaker family. An MCB may be considered for branch circuits, while an MCCB may be considered for feeder or distribution duties where the required frame and protection arrangement differ. The product label alone does not establish suitability; the actual system and coordination study remain important.
AC and DC applications must be matched to product ratings published for the relevant system. A breaker that has an AC rating should not be assumed to have an equivalent DC rating. DC selection also requires attention to system voltage, pole arrangement, fault conditions and the manufacturer's connection instructions for the specific series.
Keeping these three questions separate prevents common category errors. It also creates a more useful inquiry: instead of requesting “a breaker” without context, a buyer can state the protection function, circuit position and electrical system first.
| Device | Main protection role | Common position or use | Confirm before model selection |
|---|---|---|---|
| MCB | Overcurrent protection | Branch or final circuits in suitable low-voltage boards and equipment | Application, system voltage, rated current, poles, trip-curve requirement, breaking capacity, AC or DC use and quantity |
| MCCB | Overcurrent protection in a different frame and protection arrangement | Feeders, distribution panels, equipment and selected AC or DC projects | System voltage, rated current, poles, required breaking capacity, trip unit, accessories, installation and quantity |
| RCCB | Residual-current protection without integral overcurrent protection | Circuits where residual-current protection is coordinated with separate overcurrent protection | Electrical arrangement, residual-current requirement, ratings, poles, overcurrent coordination and local requirements |
| RCBO | Residual-current and overcurrent protection in one device | Individual circuits requiring both functions | Circuit application, ratings, poles, residual-current requirement, breaking capacity, system and market requirements |
| SPD | Limits surge voltage and diverts surge current; not a circuit breaker | Selected points in a coordinated surge protection arrangement | AC or DC system, installation point, SPD type/project requirement, system parameters, backup protection and documents |
The table is a product-family comparison, not a design calculation. A final selection should be checked by a qualified person against the installation, available fault current, conductor and load requirements, coordination needs, local rules and the selected model documentation.
An MCB, or miniature circuit breaker, is commonly used for overcurrent protection in branch and final circuits. It is frequently installed in distribution boards, control panels and equipment where the selected series is suitable for the electrical system and application.
An MCB is not selected by rated current alone. The buyer may also need to confirm:
Trip curves are especially important when loads have different starting or inrush characteristics. However, a letter printed on a breaker is not a substitute for a circuit study. The curve, rated current and breaking capacity must work together with the conductor, load, upstream device and expected fault conditions.
The applicable product standard also depends on the device and intended use. For example, IEC 60898-1 addresses certain AC circuit breakers for overcurrent protection in household and similar installations. Other low-voltage circuit breakers may fall under IEC 60947-2. A model should therefore be checked against its own technical documentation instead of assigning one standard to every MCB by default.
For a sourcing discussion, begin with the application and known electrical requirements. If a panel schedule or single-line diagram is available, it can help identify the roles of the required MCBs without turning the inquiry into a guess based only on ampere values.
Explore the OOHMAGE MCB product range
An MCCB, or molded case circuit breaker, is commonly considered for feeders, distribution panels, industrial equipment and other low-voltage applications where the required frame, ratings or protection arrangement differ from a typical branch-circuit MCB.
The spelling “molded case circuit breaker” is common in American English, while “moulded case circuit breaker” is common in British and international search. Both refer to the MCCB product category. The final device still has to be chosen from a series whose published parameters match the project.
MCCB selection may involve more variables than a simple product-family comparison:
Not every MCCB series offers the same ratings, adjustment functions or accessories. A maximum shown on one model page must not be applied to the entire category. AC and DC ratings also need to be checked separately. For DC projects, use a model with published DC parameters and follow the manufacturer's specified pole and connection arrangement.
Breaking capacity deserves explicit confirmation. It describes the breaker's ability under specified short-circuit conditions and must be considered against the prospective fault level and the relevant rating definitions. It should not be selected from a generic rule of thumb or an unverified reading from a basic meter.
When requesting a quotation, include the required current, voltage, poles, breaking capacity, trip-unit preference, accessories, application, quantity and destination market. That information makes it possible to compare the suitable MCCB series without presenting an unsupported universal range.
Explore the OOHMAGE MCCB product range
Read the MCCB selection guide
An RCCB is a residual-current operated circuit breaker without integral overcurrent protection. It monitors the balance of current in the conductors that pass through its sensing arrangement and operates when the residual-current condition reaches the device's specified operating criteria.
The phrase “without integral overcurrent protection” is essential. An RCCB should not be described as if it automatically replaces the overcurrent protection required for the circuit. The electrical arrangement must include suitable overcurrent protection and coordination where required.
An RCCB discussion should identify:
Residual-current device terminology and requirements can vary between markets and applications. The product type, operating characteristics and installation method should be confirmed against the selected model and local rules. An article can explain the device's role, but it cannot determine the protective arrangement for an unknown installation.
This distinction is also useful for procurement. If the project list simply says “RCD,” the buyer should confirm whether the requirement is for an RCCB without integral overcurrent protection, an RCBO with integral overcurrent protection, or another residual-current device defined by the project specification.
Explore the OOHMAGE RCCB product range
An RCBO is a residual-current operated circuit breaker with integral overcurrent protection. It combines the residual-current function and overcurrent protection within one device for the circuit it serves.
That combined role can simplify the product-family decision, but it does not remove the need to confirm ratings and system details. An RCBO inquiry should normally include:
The choice between an RCBO and an arrangement using an RCCB with separate MCBs is a system and project decision. An RCBO can provide both functions for an individual circuit, while an RCCB-plus-MCB arrangement separates the residual-current and overcurrent devices. The appropriate option depends on circuit organization, coordination, continuity requirements, panel design, local rules and the products specified for the project.
Do not assume that every RCBO has the same residual-current type, trip curve, pole arrangement or short-circuit rating. Compare the actual series and model documentation. If the inquiry concerns a distribution box, include the number of circuits, available layout and any device-width or busbar requirements known to the panel designer.
Explore the OOHMAGE RCBO product range
Read the RCBO overview
An SPD is not a circuit breaker. In IEC 61643 terminology, a low-voltage surge protective device is intended to limit surge voltage and divert surge current. It is selected and coordinated as part of the wider protection arrangement for transient overvoltage.
This matters because a circuit breaker and an SPD answer different questions. A breaker is selected for its specified switching and protection functions under the applicable conditions. An SPD is selected for the surge environment, electrical system, installation point, protection arrangement and its own published ratings.
An SPD inquiry may need the following information:
Do not copy an AC SPD rating into a DC or photovoltaic application. Use a product series intended for the relevant system and confirm the model parameters and coordination requirements.
Explore the OOHMAGE surge protective device range
Read the SPD selection guide
A useful shortlist begins with the project, not with a collection of similar-looking devices. The following sequence can make an inquiry more efficient.
State whether the product is intended for a branch circuit, feeder, incomer, machine, control panel, distribution board, solar/DC circuit or another identified position. If several devices are required, list each position separately.
Clarify whether the circuit needs overcurrent protection, residual-current protection, both functions in one device, or surge protection as part of the wider arrangement. This separates MCB/MCCB, RCCB/RCBO and SPD requirements before model selection begins.
Include system voltage, AC or DC use, rated current, poles, required breaking capacity, trip characteristic, residual-current requirement and any known coordination or accessory needs. Do not invent missing values; mark them for confirmation.
State the quantity, destination market, packaging or branding requirements and required technical or certification documents. Documentation should be checked for the selected series and order rather than assumed from a general category statement.
Compare the shortlist with the published model parameters, drawings and required documents. Resolve differences in voltage, poles, rating definitions, dimensions, connection arrangement or accessories before the quotation and order are finalized.
For a cross-series discussion, use the low-voltage circuit protection solutions page and send the available requirements.
Common low-voltage types include MCBs for branch-circuit overcurrent protection and MCCBs for feeder, distribution and other applications that require a different frame or protection arrangement. RCCBs provide residual-current protection without integral overcurrent protection, while RCBOs combine residual-current and overcurrent protection.
Both are circuit breakers used for overcurrent protection, but they are commonly applied in different circuit roles and product arrangements. The choice depends on the system voltage, current, poles, fault level, required breaking capacity, trip characteristics, accessories, installation and the published parameters of the selected series.
An RCCB provides residual-current protection without integral overcurrent protection. An RCBO includes residual-current and overcurrent protection in one device. An RCCB therefore needs to be considered together with the circuit's overcurrent protection arrangement.
No. An SPD is not a circuit breaker. It is used within a coordinated protection arrangement to limit surge voltage and divert surge current associated with transient overvoltage.
Only use a breaker in a DC system when the selected model has published DC ratings and is installed according to the manufacturer's DC connection requirements. Do not assume that an AC rating applies to DC use.
Provide the application, circuit role, AC or DC system, voltage, current, poles, required breaking capacity, trip or residual-current requirement, accessories, quantity, destination market and required documents. If some values are not yet known, provide the diagram or application information available and identify what still needs confirmation.
The correct product family is the first decision, not the last. Once the protection function and circuit role are clear, compare the actual MCB, MCCB, RCCB or RCBO series against the system and order requirements.
Send your application, known ratings, quantity and destination market to discuss a practical low-voltage protection product shortlist.
