Fire alarm installations often require which type of conductor?

• A. Stranded
• B. Solid
• C. Coaxial
• D. Twisted pair

Answer: (B)

Solid conductors are preferred because fire alarm wiring is typically part of the building’s fixed wiring, run through walls and conduit with little movement. A solid copper conductor fits neatly into terminals and connectors, is easier to staple or clamp in place, and tends to be cheaper for long, continuous runs. This makes for reliable terminations and a straightforward installation process in the protected, permanent portions of a building.

Stranded conductors are more flexible and are chosen where wires must bend or move, such as portable or highly vibration-prone applications. Coaxial and twisted pair are intended for data or communications signals rather than standard fire alarm power and control circuits, so they don’t fit the common needs of fixed alarm wiring.