The conductors in Conduit II are protected by a circuit breaker of what type and rating?

• A. 60A, two-pole breaker
• B. 80A, three-pole breaker
• C. 100A, two-pole breaker
• D. 40A, two-pole breaker

Answer: (B)

When three current-carrying conductors are in a single conduit, protecting them requires a breaker with three poles that trips all phases together. That common-trip feature is essential for safely disconnecting the entire circuit if a fault occurs on any phase. The 80A rating is chosen to match the conductors’ ampacity and the load’s expected current, ensuring the protection device will interrupt before the conductors overheat. A two-pole breaker wouldn’t disconnect all phases in a three‑phase setup, and a different rating on a two-pole wouldn’t provide the proper protection for a three-conductor, three‑phase circuit. So an 80A, three-pole breaker is the appropriate choice.