Minimum separation for Class A circuit's outbound and return paths in a hallway 9 feet wide?

Minimum separation for Class A circuit's outbound and return paths in a hallway 9 feet wide?

• A. 4 feet
• B. 2 feet
• C. 6 feet
• D. 8 feet

Answer: (A)

The fundamental idea is to prevent a single incident in the hallway from damaging both legs of a Class A signaling circuit by keeping the outbound and return conductors physically apart. In NFPA 72 and typical fire alarm practice, Class A circuits require a minimum separation between the two conductors when they run in parallel in the same space, so a single fault (like mechanical damage, moisture, or a fast-moving object) is less likely to take out both paths at once. The minimum separation is four feet, which the hallway width of nine feet comfortably accommodates. So, four feet is the correct minimum. If the hallway were narrower or space didn’t allow four feet, you’d need to route the conductors in separate conduits or channels to maintain separation. The other distances are either not enough to meet the required minimum or exceed what’s required for a standard installation.

The fundamental idea is to prevent a single incident in the hallway from damaging both legs of a Class A signaling circuit by keeping the outbound and return conductors physically apart. In NFPA 72 and typical fire alarm practice, Class A circuits require a minimum separation between the two conductors when they run in parallel in the same space, so a single fault (like mechanical damage, moisture, or a fast-moving object) is less likely to take out both paths at once. The minimum separation is four feet, which the hallway width of nine feet comfortably accommodates. So, four feet is the correct minimum. If the hallway were narrower or space didn’t allow four feet, you’d need to route the conductors in separate conduits or channels to maintain separation. The other distances are either not enough to meet the required minimum or exceed what’s required for a standard installation.