Difference Between MCCB and MCB

Edited by Diffzy | Updated on: April 30, 2023


Difference Between MCCB and MCB

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Most individuals don't understand the distinctions between MCB and MCCB. Despite the fact that both are circuit breakers, there are significant distinctions between the two that allows for their specialization for various tasks. However, it's crucial to grasp what the abbreviations stand for before we discuss each product's distinguishing characteristics. Miniature Circuit Breakers are abbreviated as "MCB," while Molded Case Circuit Breakers are abbreviated as "MCCB."

In this article, let’s understand the differences between the two of them in detail.


The key distinction between the two is their capacity, with the MCB having an interrupting rating of under 18,000 amps and a rating under 100 amps. Consequently, because they only serve low circuits, their trip characteristics might not be altered.

On the other hand, an MCCB has a trip characteristic that can be adjusted for higher models. Depending on the situation, this kind of circuit breaker will typically offer amps as high as 2,500 or as low as 10. Between 10,000 and 200,000 amps is the range of their interrupting ratings.

The MCB is mostly used for low-energy requirements, like residential wiring or small electronic circuits, based on their power capacity. The MCCB, on the other hand, is better adapted to supply energy for high-power machinery.

Although an MCCB has a greater capacity than an MCB, both are considered low voltage circuit breakers and as such must adhere to IEC 947 regulations. Some MCCB units feature electrical motor operators, making it possible to trip them with just a remote control for convenience. They could be used as standby power for commercial or industrial purposes, using an automatic transfer switch.

An MCB is a straightforward, simple-to-use, and maintenance-free device. It is simple to replace an MCB. The trip unit, which powers the MCB (Miniature Circuit Breaker), is an essential component. The electromagnet in the MCB circuit protects against short-circuit current, and the bi-metal in the circuit prevents overload current.

Difference Between MCCB and MCB in Tabular Form

Parameters of Comparison MCCB MCB
The utilization MCCBs are utilized in areas with significant energy needs, such as high-power machinery in factories or for commercial purposes. Low-energy applications, like small electrical circuits or residential wiring, take advantage of it.
Their operation MCCBs can operate at 2500 amps. MCBs only have 100 or fewer amps.
The trip features You can change the trip's attributes. Trip features cannot be changed.
Extra information The range of interrupting ratings is 10,000 to 20,000 amps. Rating for interruptions under 18000 amps.

What is MCCB?

An electrical protection device known as a molded case circuit breaker (MCCB) is used to safeguard an electrical circuit from excessive current, which can result in overload or short circuit. MCCBs have changeable trip settings and a current rating of up to 2500A, making them suitable for a variety of voltages and frequencies. For system isolation and protection, these breakers are utilised in place of tiny circuit breakers (MCBs) in large-scale PV systems.

To offer the trip mechanism for isolation and protection, the MCCB combines a thermal element, which is temperature sensitive, with a magnetic element, which is current sensitive. As a result, the MCCB can offer:

  • Overload Defense,
  • Defending against short circuit currents using electrical fault protection
  • Electrical disconnect switch.

Protection from Overload

The temperature-sensitive component of the MCCB uses overload protection. This part is basically a bimetallic contact, which is a contact made of two metals that expand at different rates when heated. The bimetallic contact will enable electric current to pass through the MCCB under typical working circumstances. Due to the various thermal rates of heat expansion within the contact, the bimetallic contact will begin to heat up and bend away when the current exceeds the trip threshold. The contact will eventually bend to the point where it physically pushes the trip bar and unlatches the contacts, interrupting the circuit.

In order to accommodate a brief period of overcurrent that is frequently observed during the operation of particular devices, such as inrush currents experienced while starting motors, the thermal protection of the MCCB will typically incorporate a time delay. Due to the time delay, the circuit can function normally under these conditions without tripping the MCCB.

Protection from electrical short circuit currents

Now, relying on the electromagnetic concept, MCCBs respond instantly to a short circuit problem. So, whenever current is flowing through the MCCB, a solenoid coil inside the device produces a modest electromagnetic field. Moreover, the electromagnetic field produced by the solenoid coil is seldom apparent when it is functioning normally. A short circuit failure in the connection, however, causes a significant current to start flowing through the solenoid. As a consequence, a powerful electromagnetic field is produced, pulling the trip bar and opening the contacts.

Switch for electrical disconnection

MCCBs have tripping mechanisms in addition to human disconnect switches for usage during emergencies or maintenance procedures. When the contact opens, an arc might be formed. MCCBs include inbuilt arc dissipation systems to quench the arc as a defense against this.

Understanding MCCB Ratings and Characteristics

Manufacturers of MCCBs are obligated to give information about the MCCB's operating characteristics. Here are some examples of typical parameters:

  • The maximum current that the MCCB is rated to handle. Rated Frame Current- The maximum range of the adjustable trip current is determined by this rated frame current. The size of the breaker frame is decided by this parameter.
  • Rated current- Now, whenever the MCCB trips due to overload protection, it is dependent upon the rated current value. Hence, to a maximum of the rated frame current, this value can be changed.
  • Rated insulation voltage- This number is the highest voltage that the MCCB can withstand under laboratory circumstances. To offer a safety buffer, the rated voltage of MCCBs is normally lower than this figure.
  • Rated working voltage- The rated voltage for the MCCB's continuous operation is this figure. The voltage is often equal to or similar to the system voltage.

Sizing of the MCCB

An electrical circuit's projected operating current and potential fault currents should be used to size the MCCBs. When choosing MCCBs, there are three key considerations:

  1. The system voltage should be comparable to the MCCB's rated working voltage (Use).
  2. The MCCB's trip value needs to be modified to account for the load's current draw.
  3. The theoretically conceivable fault currents must be greater than the MCCB's breaking capacity.

The maintenance

Now, it's crucial to keep an eye out for distorted contacts or breaks in the casing or insulation while visually inspecting an MCCB. You should proceed with caution if there are any burns on the contact or case. Also, to ensure the smooth operation of the manual disconnect switch and internal moving parts, some MCCBs need proper and regular lubrication. The components of MCCBs may deteriorate as a result of dirt buildup. Any conducting materials in the dirt could establish a conduit for current and result in an internal fault.

What is MCB?

When selecting electrical appliances or devices, safety comes first. An overload or short circuit occurs as a result of power fluctuations or excessive current flow. Therefore, it is crucial to include a device as a safety element to give electrical devices and circuits overcurrent protection. One of the most popular tools for circuit protection, in the beginning, was the fuse. When there is an overload of current, a fuse's metal wire or strip melts, blocking or interrupting the flow of current.

A considerably more effective and compact electronic device known as an MCB, or miniature circuit breaker, has recently replaced the fuse.

Now, have you ever considered what would happen to the fans, washing machines, ovens, refrigerators, and a host of other household appliances in the event of a short circuit or an excess of current? If the correct circuit breakers are not fitted in the equipment, they burn and cause fire mishaps. One such safety item with an electro-mechanical mechanism of action is the miniature circuit breaker.

An automated switch called an MCB activates when too much current is flowing through the circuit. Without any manual replacement, it can be closed again. Fuse replacement or rewiring is required in the case of fuses, depending on the type of MCB used. Fuse is hence referred to be one of the sacrificial devices. This is the primary reason MCBs are utilized in place of fuses in the majority of circuits. Additionally, the switches in the MCB immediately shut off whenever there is a failure in the circuit, making it simple to identify the problem with the device.

Handling The supply is rapidly restored, and MCB is rather safe. Miniature Circuit Breakers (MCBs) are inexpensive to maintain and can be rapidly reset. MCBs protect against overload current and solenoid short circuit current using a bi-metal respective basis.

The Types

When the current reaches two to three times the actual current rating, A Type MCB trips off the circuit. Because a type MCB - Miniature Circuit Breaker - is extremely sensitive to a short circuit, we can use it to make semiconductors. When the current surpasses 3-5 times the actual current flow, a B Type MCB switches off the circuit and is used for cable protection.

The C Type MCB is used in home and commercial appliances like transformers, fluorescent lighting circuits, and IT equipment like personal computers, servers, and printers. It trips off the circuit when the current reaches 5 to 10 times the actual current flow.

When the current is 10–20 times greater than the actual current flow, the D-Type MCB shuts off the circuit and provides significant resistance. Motors use it in their design. K Type MCBs are used in heavy-duty load devices including compressors, winding motors, and X-ray equipment because they can sustain current flows that are up to 8–12 times greater than the actual current flow.

The working of MCB

The bimetallic strip becomes heated and bends when there is an overflow of current through an MCB (Miniature Circuit Breaker). A latch is released by the bi-metallic strip deflecting. By halting the circuit's current flow, the latch forces the MCB to switch off. This procedure aids in protecting the gadgets or equipment from dangers brought on by overload or overcurrent. MCB needs to be manually switched ON in order to restart the current flow.

Now, whenever a short circuit occurs, the current rises abruptly and in unpredictably, which basically causes the solenoid plunger to be electromechanically displaced. Also, when the plunger strikes the trip lever, the circuit breaker contacts open, and it automatically releases the latch mechanism.

The majority of electrical appliances used for industrial or home applications contain MCBs, which are essential for the safety and effective operation of electric devices. Lights, heaters, and fans are examples of household appliances that need MCBs to continuously monitor and safeguard the connection.

Main Differences Between MCCB and MCB In Points

Now, let’s look at the major differences between MCCB and MCB in the following points:

  • An MCCB can handle 2,500 amps, however, an MCB can only handle less than 100 amps.
  •  An MCB has an interrupting rating of 18,000 amps, whereas an MCCB has a rating of up to 200,000 amps.
  • While MCCBs are typically used for business or industrial applications, MCBs are typically placed for residential use.
  • Both are low-voltage circuit breakers made by IEC 947 specifications.
  • In most cases as backup power, some MCCB units are designed specifically to respond to remote control signals. For safety concerns, circuit breakers are fitted.
  • Both are set up in niches on the wall that are designed to allow installation and removal simply without affecting the switchgear or disrupting the entire system. Both are ordinarily arranged in stages for space efficiency and are specifically designed to handle the direct current.


Therefore, now we can conclude that we have gathered enough information regarding MCB and MCCB. It’s very essential to understand the differences between the two of them for properly maintaining our security and safety.


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"Difference Between MCCB and MCB." Diffzy.com, 2023. Tue. 06 Jun. 2023. <https://www.diffzy.com/article/difference-between-mccb-and-mcb-680>.

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