Why is 18 AWG commonly specified for single conductors?

• A. To ensure adequate cross section and strength
• B. To minimize cost
• C. To maximize flexibility
• D. To simplify insulation

Answer: (A)

The main idea is that conductor size is chosen to provide enough current-carrying capacity and mechanical strength for its typical path and load. For single-conductor runs in alarm systems, 18 AWG has a cross-sectional area large enough to safely carry the expected current without overheating and to withstand the handling and routing through panels, devices, and conduit. At the same time, it isn’t so thick that it becomes difficult to route or terminate, making it a practical, reliable choice. While cost and flexibility matter in some contexts, the primary reason 18 AWG is common is that it offers adequate cross section and strength for typical low-voltage alarm circuits.