Which statement about the difference in fire safety ratings between plenum and riser cables is true?

• A. Riser Cables Have Stricter Fire Load Requirements Than Plenum.
• B. Plenum Cables Have Stricter Fire Load Requirements Than Riser.
• C. Fire Load Requirements Are Identical For Both.
• D. Plenum Cables Are Not Designed For Fire Retardancy.

Answer: (A)

The essential idea is that fire performance ratings for cables depend on where the cable is installed. In plenum spaces, where air moves and smoke can spread quickly through ventilation ducts, cables must be plenum-rated with stricter flame-spread and smoke-development requirements. Riser cables, used for vertical runs between floors, are flame-retardant but do not have to meet the same stringent plenum standards. So plenum cables have the stricter fire safety ratings compared to riser cables. The notion that riser cables are stricter, or that fire safety ratings are identical, isn’t correct, and plenum cables are indeed designed for fire retardancy.