A 10 A, Type C Miniature Circuit Breaker (MCB) will trip at fault currents

• A. between 10 A and 50 A
• B. less than 10 A
• C. greater than 100 A
• D. between 50 A and 100 A

Answer: (D)

Type B MCB:
Type B devices are generally suitable for domestic applications.
They are designed to trip at fault currents of 3 - 5 times rated current.

Type C MCB:
Type C devices are the normal choice for commercial and industrial applications
These devices are designed to trip at 5 - 10 times rated current

Type D MCB:
The Type D devices have more limited applications, normally in industrial use where high inrush currents may be expected.
Type D devices are designed to trip at 10 - 20 times.