Why are motor circuits commonly protected by a circuit breaker?

• A. motors draw a surge of current when first started.
• B. they require constant current control.
• C. they operate at a fixed resistance.
• D. they never experience inrush.

Answer: (A)

The main idea is that motors draw a surge of current when they start. When a motor is not yet spinning, its windings look almost like a simple low-resistance path, and there’s no back-EMF to limit current. That means the starting current can be several times higher than the running current. A circuit breaker protects the circuit by interrupting power if the current becomes too high for too long, or if a short circuit occurs. Many breakers are designed to tolerate brief inrush surges (magnetic action for short spikes and thermal action for overload), so normal motor startup doesn’t trip the breaker, while sustained overloads or a fault do.

Other options don’t fit because motors aren’t protected by constant current control in normal operation, their windings don’t have a fixed resistance during operation, and it’s not true that motors never experience inrush.