Which cabling classification is rated for vertical runs between floors?

• A. Plenum (CMP)
• B. Shielded (SC)
• C. Riser (CMR)
• D. Outdoor-rated

Answer: (C)

Vertical runs between floors require cabling that confines fire and limits flame travel along the shaft. Riser-rated cabling, known as CMR, is designed exactly for these in-building vertical pathways. It’s tested to resist flame spread as cables run through risers, helping meet building-code requirements and keeping vertical spaces safer.

Plenum-rated cabling (CMP) is intended for air-handling spaces where smoke must be minimized in ventilating plenums, and it’s overkill and more costly for standard risers unless that space is a plenum. Shielded cabling focuses on reducing electromagnetic interference, not fire performance, so it doesn’t address the needs of a vertical run. Outdoor-rated cabling is built to withstand weather and moisture outside the building, not for interior vertical shafts.

So, the best fit for vertical runs between floors is the riser-rated cabling.