The major difference between a relay, a contactor, and a starter is the size of the ______ they can handle.

• A. Voltage
• B. Load
• C. Poles
• D. Coil

Answer: (B)

These devices are all switches used to control power to a load, but they’re built to handle different amounts of current. A relay is a small switch designed to control a low-current circuit, often used to energize other control devices. A contactor is a larger switch intended to carry higher currents and is used to switch motors or other heavy loads; it has sturdier contacts and higher current ratings. A starter goes even further, typically used to start and protect large motors, and it combines switching with motor protection (like overload protection). So the main practical difference is the amount of load (current and power) they’re rated to switch in service.