What Is an Air Circuit Breaker?

The name “air switch” can sound odd. What is an air circuit breaker, and what does it do? CHINENG explains.

What is an air circuit breaker?

Also called an air breaker or MCB, it automatically opens when current exceeds its rating. Besides making and breaking circuits, it protects against short circuit, severe overload, and undervoltage.

Main roles

1. Leakage protection: isolates power quickly when leakage appears to protect people and property.

2. Short-circuit protection: disconnects immediately if wiring faults create a short.

3. Current limiting: cuts high fault current before appliances burn out.

4. Isolation: separates unsafe current levels from people and equipment (currents under about 30 mA are generally considered safer for body contact).

Install air breakers carefully and follow electrical safety practice.