What is the difference between a relay and a contractor?

• A. Contractors switch higher currents and circuit breakers switch lower currents
• B. Relays switch higher currents and contractors switch lower currents
• C. They are identical in current handling
• D. Contractors switch voltage, not current

Answer: (A)

The difference comes from how much current each device is built to switch and what its job is. A relay is used to switch control circuits or low-current loads; its coil draws a small amount of current to pull in the contacts, but the contacts themselves carry only the smaller current of the control side. A contractor (contactor) is designed to handle large load currents, switching motors, heaters, and other high-current devices. In practice, the same coil-activated mechanism controls the higher-current path through the contacts, separate from the coil. Circuit breakers aren’t used for normal on/off switching of loads; they protect circuits by interrupting current when faults occur and are rated for high interruption, not routine switching. So the key idea is that contractors handle higher currents and relays handle lower currents, with circuit breakers serving a protective role rather than regular switching.