🔍 Key Concepts

• Molded‑case circuit breaker (MCCB) internal parts: fixed contacts, moving contacts, terminals, and trip mechanism • How the current path enters and leaves the breaker (line and load terminals) • Difference between a contact (where the circuit opens/closes) and a terminal (where an external cable connects)

💭 Think About

• Look closely at where label "C" is pointing: is it on the part that actually touches another piece to open/close the circuit, or on the point where an external conductor would be bolted on? • Ask yourself whether the part at "C" moves when the handle operates, or whether it stays in place and simply provides a mounting point for a wire or bus bar. • Compare the location of "C" to the trip mechanism: does it look like a bar linked to the trip unit, or is it clearly part of the current‑carrying path?

✅ Before You Answer

• Verify whether label "C" is on a current‑carrying surface inside the breaker or on an external connection point for a cable. • Check if the component at "C" is mechanically linked to the operating handle (typical of moving contacts or trip bars). • Make sure you can clearly distinguish between a contact surface (paired with another contact) and a terminal lug (where you’d tighten a screw onto a cable).