Comparison

MCB vs MCCB: Which Circuit Breaker Fits the Application?

MCBs are compact fixed-setting breakers for final circuits. MCCBs are higher-rated and adjustable. Compare current, interrupting capacity and standards.

Electrical & Power · Last reviewed October 17, 2026

Short answer: use an MCB for final circuits and small loads where a fixed setting is enough. Use an MCCB for feeders, larger loads and any place that needs a higher interrupting capacity or an adjustable trip. Product standards and ratings vary by region, so check the datasheet.

	MCB (miniature)	MCCB (molded case)
Typical current range	Up to about 125 A	From small ratings up to 1,600 A and more
Interrupting capacity	Typically 6 to 25 kA	Typically 10 to 150 kA, depending on the frame
Trip settings	Fixed. Characteristic curves such as B, C and D set the magnetic trip level	Thermal-magnetic with adjustment, or electronic with long, short and instantaneous settings
Adjustability	None, other than choosing another device	Often adjustable, which helps coordination
Mounting	DIN rail or panel board	Panel or switchboard, bolted or plug-in
Accessories	Limited (auxiliary contacts, shunt trips)	Wide range: shunt and undervoltage trips, motor operators, ground-fault modules
Typical standards	IEC 60898-1 for household, IEC 60947-2 for industrial. In North America, UL 489 (and UL 1077 for supplementary protectors, which are not branch-circuit protection)	IEC 60947-2, and UL 489 in North America
Cost and size	Smaller and cheaper	Larger and costlier

Trip curves

The curve letter of an MCB sets the current at which the magnetic part trips instantly. Under the common IEC 60898 definitions, type B trips at about 3 to 5 times the rated current, type C at 5 to 10 times and type D at 10 to 20 times. Motor and transformer inrush calls for a higher curve, while long cables with low fault current may need a lower one. An MCCB gives a choice of settings on one device.

How to choose

Find the load current and the available fault current at the device. The interrupting rating must be above the fault current.
Decide whether a fixed setting is enough, or whether coordination needs adjustable trips.
Check the inrush of the load against the trip curve or setting.
Check which standard applies in the region and the project, and whether the device is for branch-circuit protection.
Consider the accessories needed: remote trip, ground-fault protection or motor operation.

Common mistakes

Choosing by ampere rating alone, with an interrupting capacity below the available fault current.
Using a supplementary protector where branch-circuit protection is required.
Using a type B MCB on a circuit with high inrush, so that it trips on start.
Using the same curve letter assumptions from one standard on a device made to another.

Related tools and labs

Calculators, labs and simulators are part of the All-Access Pass.

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Questions

Can an MCCB replace an MCB?

In some cases yes, but it is larger and costs more, and it may not fit the enclosure. Check the ratings, the standard and the coordination.

What does interrupting capacity mean?

The highest fault current the device can safely clear. It must exceed the available fault current at its location.

Educational material. Examples use simplified, hypothetical inputs and are not a design, a construction document or professional engineering advice. Confirm requirements with the codes and standards adopted where the work is built and with a licensed engineer.

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