Can I replace an MCB with an MCCB in my distribution board?

Yes, in most cases you can use an MCCB where an MCB would normally be used, but not vice versa. MCCB offers higher current ratings (16-630A vs MCB's 6-125A) and higher breaking capacities. However, MCCB has larger physical dimensions and costs more. For new designs, MCCB is preferred for commercial/industrial applications where scalability and adjustability matter. For residential applications, MCB remains the standard choice due to lower cost and compact size.

What is the typical price difference between MCB, MCCB, and ACB?

FOB Shanghai pricing guide: MCB (6-63A) = $2.50-$12.00/pc. MCCB (16-630A) = $18-$350/pc. ACB (630-6300A) = $450-$2,500/pc. Price varies by breaking capacity, brand, and accessories (shunt trip, under-voltage release, motor operator). ACB with electronic release costs $200-$500 more than thermal-magnetic versions. Volume discounts of 8-15% typically apply for orders of 500+ pieces.

What does 'breaking capacity' mean and why does it matter?

Breaking capacity (Icn or Icu) is the maximum short-circuit current a circuit breaker can safely interrupt without causing damage or danger. Expressed in kA (kiloamperes). If a fault occurs and the breaking capacity is exceeded, the breaker may fail catastrophically — causing fire, explosion, or an inability to isolate the fault. Always select a breaker with breaking capacity higher than the maximum potential short-circuit current at its installation point. For most commercial installations, 25-36kA is sufficient. Industrial plants may require 50-100kA.

Should I choose thermal-magnetic or electronic MCCB?

Choose thermal-magnetic for: simple applications, budget constraints, where settings won't need adjustment. Choose electronic for: complex distribution systems, variable loads, where you need: (1) adjustable long-time current (0.8-1.0× In), (2) adjustable short-time trip, (3) ground fault protection, (4) communication capability (Modbus/Profibus). Electronic MCCBs cost $80-$200 more but offer better protection coordination in multi-level distribution systems. Most industrial applications above 250A benefit from electronic release.

MCCB vs ACB vs MCB: Complete Circuit Breaker Type Comparison Guide

Last updated: May 2026 | Reading time: 10 minutes

At a Glance

Type	Current Rating	Voltage	Breaking Capacity	Poles	Trip Type	Price (FOB)	Best For
MCB	6A – 125A	230/400V AC	3kA – 25kA	1P, 2P, 3P, 4P	Thermal (fixed)	$2.50 – $12	Residential, light commercial, lighting circuits
MCCB	16A – 630A	400/690V AC	10kA – 100kA	2P, 3P, 4P	Thermal-magnetic / Electronic	$18 – $350	Commercial buildings, industrial plant, power distribution
ACB	630A – 6300A	400/690V AC	35kA – 150kA	3P, 4P	Electronic (adjustable)	$450 – $2,500	Main switchboards, heavy industry, large transformers

MCB — Miniature Circuit Breaker

What it is: The most common protective device in electrical installations. MCBs protect circuits from overload and short-circuit in residential and light commercial applications.

Technical Specifications

Current rating: 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, 80A, 100A, 125A
Voltage: 230V (single-phase), 400V (three-phase)
Breaking capacity: 3kA (lowest), 6kA (standard), 10kA (high), 25kA (industrial)
Characteristic curves: Type B (3-5× In — lighting), Type C (5-10× In — general), Type D (10-20× In — inductive)

Applications

Residential distribution boards
Commercial office lighting circuits
Small motor protection (Type D)
Panel board branch protection

✅ Advantages

Compact size — fits standard DIN rail enclosures
Low cost — most economical protection option
Reliable — simple thermal mechanism, proven technology
Easy to replace — standardized form factor across manufacturers

❌ Limitations

Fixed trip settings — cannot be adjusted
Current rating capped at 125A
Not suitable for DC applications above 60V
Cannot be remotely tripped or monitored

MCCB — Molded Case Circuit Breaker

What it is: Heavy-duty circuit protection for commercial and industrial applications. MCCBs offer higher current ratings, adjustable trip settings, and modular accessories.

Technical Specifications

Current rating: 16A to 630A (some models up to 1600A)
Voltage: 400V standard, up to 690V for industrial
Breaking capacity: 10kA, 25kA, 36kA, 50kA, 70kA, 100kA
Trip unit: Fixed thermal-magnetic OR adjustable electronic
Dimensions: 75-150mm wide × 150-250mm tall (varies by rating)

Applications

Commercial building main distribution
Industrial plant motor protection
Generator output protection
Transformer secondary protection
Capacitor bank protection

✅ Advantages

Adjustable trip settings (electronic version) — fine-tune protection to load characteristics
Accessories: shunt trip, under-voltage release, motor operator, communication module
Breaking capacity up to 100kA — handles heavy fault currents
Can be manually or automatically reset after trip
Suitable for DC applications (with derating)

❌ Limitations

Larger physical size than MCB — requires more panel space
Higher cost — 3-10× the price of equivalent MCB
Electronic versions require configuration and commissioning

How to Size an MCCB

For a 3-phase load, calculate: In = (kW × 1000) / (1.73 × 400 × cosφ)

Select MCCB rating: In × 1.25 (25% overhead for motor starting)

Breaking capacity must exceed maximum short-circuit current at installation point.

ACB — Air Circuit Breaker

What it is: The heavyweights of low voltage protection. ACBs handle currents from 630A to 6300A and are used in main switchboards, large industrial plants, and power distribution systems.

Technical Specifications

Current rating: 630A, 800A, 1000A, 1250A, 1600A, 2000A, 2500A, 3200A, 4000A, 6300A
Voltage: 400V (standard), 690V (industrial)
Breaking capacity: 35kA, 50kA, 65kA, 100kA, 150kA
Trip unit: Electronic, fully adjustable (long-time, short-time, ground fault)
Dimensions: Typically 400-600mm wide × 400-600mm tall × 250mm deep (draw-out type)

Applications

Main switchboard incomers (main breakers)
Large transformer protection
Large motor starting (630A+)
Power generation facilities
Data center power distribution

✅ Advantages

Highest current ratings (up to 6300A) — the only choice for main breakers above 1600A
Fully adjustable electronic release — precise protection coordination in complex systems
Draw-out design — can be withdrawn for maintenance without de-energizing the busbar
Communication capability — Modbus, Profibus, Ethernet for SCADA integration
Zone selective interlocking — coordinate protection to minimize outage scope

❌ Limitations

High cost — $450-$2,500 per unit plus accessories
Large physical dimensions — requires dedicated switchgear rooms
Complex installation — requires qualified electrical engineers
Ongoing maintenance required — annual testing and calibration

Selection Decision Matrix

Your Requirement	Choose MCB	Choose MCCB	Choose ACB
Current ≤ 125A	✅	✅	❌
Current 125A-630A	❌	✅	✅ (if budget allows)
Current above 630A	❌	❌	✅ Only option
Budget under $15/unit	✅	❌	❌
Need adjustable settings	❌	✅ (electronic)	✅
Main switchboard (>1600A)	❌	❌	✅ Only option

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Zhebao Electric manufactures MCB, MCCB, and ACB across the full current range. Tell us your requirements — we'll recommend the right type and provide samples.

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