In some commercial fire alarm installations, what may be required by code?

• A. Solid wire
• B. Stranded wire
• C. Coaxial cable
• D. Fiber optic cable

Answer: (A)

In many commercial fire alarm installations, the wiring in walls and ceilings is fixed and largely nonflexing. Codes sometimes require solid conductors for these fire alarm signaling circuits because solid wire terminates more reliably in screw terminals and device lugs found on panels, pull stations, and detectors. Solid conductors stay more rigid in terminations, reducing the chance of loose connections or strand fraying that can occur with stranded wire over time. This reliability in fixed installations is important for life-safety systems, where a secure, continuous connection is critical.

Coaxial and fiber optic cables are not typically used as the standard signaling conductors for fire alarm loops; they serve other functions (data/video transmission or high-bandwidth networks) and require different terminations and codes. Stranded wire, while common for many low-voltage circuits due to its flexibility, can pose termination challenges in fixed fire alarm hardware and may not be preferred in certain code requirements for concealed runs.

So, the code may specify solid wire for these installations to ensure robust, dependable terminations in fixed, in-wall fire alarm circuits.