What device interrupts electrical overload?

• A. Relay
• B. Breaker
• C. Overload
• D. Contactor

Answer: (B)

Overcurrent protection is provided by devices that automatically interrupt current when it goes above a safe level. The device that does this is a circuit breaker. It senses excessive current and trips, opening the circuit to stop the flow and protect wiring and equipment. Breakers are designed to handle both overloads (slower, sustained overcurrent) and short circuits (very high instantaneous current) and can be reset after tripping. This differs from a relay or a contactor, which are switches controlled by another circuit and do not by themselves protect against overload; they will open or close circuits only as commanded. An overload is not a device—it’s the condition the protection system responds to. In a UPS context, the breaker prevents damage by interrupting current when load or fault conditions exceed safe limits.