What is true about the difference between a main-lug panel and a main breaker panel?

• A. A main-lug panel lacks a main disconnect and requires a separate external disconnect
• B. A main breaker panel has a built-in main disconnect
• C. A main-lug panel includes a utility meter
• D. A main breaker panel cannot feed a subpanel

Answer: (A)

The difference hinges on whether the panel includes a single disconnect to de-energize all circuits. A main-lug panel has lugs for the incoming service conductors but no main switch to shut off everything in the panel, so an external disconnect is required to de-energize the entire setup. A main-breaker panel, on the other hand, has a built-in main disconnect—the main breaker—that can disconnect all power to the panel with one device. The meter isn’t part of the panel itself, it sits upstream at the service point. And a main-breaker panel can feed a subpanel by providing a feeder to another panel, so the idea that it cannot feed a subpanel isn’t correct.