When alarm conductors are installed between floors, what rating must the cable have?

When alarm conductors are installed between floors, what rating must the cable have?

• A. Service
• B. Power
• C. Riser or Plenum
• D. Standard

Answer: (C)

When alarm conductors are installed between floors, the cable must have a riser or plenum rating to ensure safety and compliance with building codes. Riser-rated cables are specifically designed for vertical spaces between floors, providing increased fire resistance. They help prevent the spread of flames and smoke upward into higher floors of a building. This is crucial in maintaining safety during emergencies, as it limits the risk of a fire spreading through the building's vertical spaces where these cables are installed.

Plenum-rated cables are used in spaces that facilitate air circulation, such as air ducts, where they may be exposed to higher temperatures and are also required to have superior fire-resistant properties. Choosing the correct rating is essential for ensuring the integrity of the fire safety systems and for minimizing potential hazards related to fire and smoke propagation.

The other rating types, such as service and power, do not meet the specific requirements for fire safety in vertical installations, and standard cables lack the necessary fire-resistance features for such applications. Thus, the riser or plenum rating is the appropriate choice for alarm conductors installed between floors.