Basic Difference Between MCB, MCCB, ACB, and RCCB – Interview Guide for Electrical Freshers

Basic Difference Between MCB, MCCB, ACB, and RCCB – Interview Guide for Electrical Freshers

If you're preparing for an electrical engineering interview, one of the most common technical questions you'll face is:

“What is the difference between MCB, MCCB, ACB, and RCCB?”

If you're preparing for an electrical engineering interview, one of the most common technical questions you'll face is:

“What is the difference between MCB, MCCB, ACB, and RCCB?”

This article will help you answer confidently with clear points and real examples.

1. MCB – Miniature Circuit Breaker

Use: Protection from overload and short circuit

Range: Up to 100A

Application: Homes, small circuits

Tip: Use for low power devices, lights, fans

2. MCCB – Moulded Case Circuit Breaker

Use: Protection from overload, short circuit, earth fault

Range: Up to 2500A

Application: Industrial machines, LT Panels

Tip: MCCB is bigger than MCB and has adjustable settings

3. ACB – Air Circuit Breaker

Use: High current protection and switching

Range: 800A – 6300A

Application: Main LT Panels in commercial buildings

Tip: Used as incomer in large distribution systems

4. RCCB – Residual Current Circuit Breaker

Use: Leakage current protection, electric shock

Range: 25A – 100A

Application: Homes, offices

Tip: RCCB must be combined with MCB for full protection

Quick Comparison:

Device Protection Type Current Range Application

MCB Overload, Short Circuit Up to 100A Homes, small panels

MCCB Overload, Short, Earth Up to 2500A Industrial panels

ACB Overload, High Currents Up to 6300A Main LT Panels

RCCB Leakage Current Only Up to 100A Home safety

Conclusion for Interview:

Always remember:

MCB & MCCB = Current protection

RCCB = Leakage protection

ACB = High load protection and switching

Answer with clarity and real examples during interviews!