In both NFPA 72 and CAN/ULC-S524, a 'Class B' circuit is defined as:

Question: In both NFPA 72 and CAN/ULC-S524, a 'Class B' circuit is defined as:

Answer options:

• A looped circuit that returns to the panel
• A circuit that provides a redundant path
• A circuit that must use fiber optics ✅ A radial circuit where a single break results in loss of communication to devices beyond the break

Correct answer: A radial circuit where a single break results in loss of communication to devices beyond the break

Explanation: NFPA 72 (USA) uses Class A/B/X/N. Canada's S524 uses Class A and Class B for wiring configurations. Class B is non-redundant (radial).