What is the purpose of a permanently fixed barrier when routing power-limited fire alarm cables near power cables?

• A. To provide EMI shielding
• B. To maintain fire rating only
• C. To reduce heat transfer
• D. To physically separate and reduce EMI

Answer: (D)

The key idea is preventing electromagnetic interference from nearby power conductors from affecting the fire alarm cables. A permanently fixed barrier provides a solid physical separation between the two cable sets, which reduces the coupling of electrical noise (EMI) from the power cables into the fire alarm cables. This helps ensure reliable signaling from the fire alarm system. It isn’t primarily about shielding the cables, altering heat transfer, or maintaining a fire rating alone—the barrier’s main purpose is to keep the circuits apart to minimize EMI.