Which statement about 22 AWG wiring is accurate for door/window circuits?

• A. Two-conductor 24 AWG cable used for door/window circuits.
• B. Two-conductor 22 AWG cable used for simple door/window circuits.
• C. Three-conductor 22 AWG cable used for power.
• D. Two-conductor 18 AWG cable used for sensors.

Answer: (B)

Door/window circuits are signaling lines in an alarm system, carrying only a small current between the sensor and the control panel. For simple door/window sensors, a two-conductor cable of 22 AWG is the typical, practical choice. It provides enough current capacity for the reed switch and supervision loop, while remaining easy to install and cost-effective for common residential runs. Using a thinner 24 AWG is less robust and more prone to damage over time, so it’s not the standard for these circuits. A three-conductor setup isn’t needed for a basic door/window loop, since power and signaling aren’t carried on separate conductors in the usual simple installation. And 18 AWG is thicker than necessary for these low-current sensors and is generally reserved for higher-current or longer runs. Therefore, two-conductor 22 AWG for simple door/window circuits accurately reflects common practice.