Which of the following describes acceptable grounding methods for an alarm panel?

• A. Ground to a wooden stake
• B. Ground to a glass window frame
• C. Ground to a metallic cold water pipe and earth soil ground rod
• D. Ground to a plastic pipe

Answer: (C)

Grounding an alarm panel requires giving it a real, low-impedance path to earth through conductors that are part of the building’s grounding system. Grounding to a metallic cold water pipe bonded to the building’s grounding network, and to an earth soil ground rod, provides that solid path to earth. The water pipe serves as a conductive route already connected to the structure’s ground, while the ground rod adds a dedicated electrode to dissipate fault currents and surges into the earth. Together, they establish a proper reference and safety path for the system.

Grounding to a wooden stake, a glass window frame, or a plastic pipe won’t work because those materials are insulators and do not provide a conductive path to earth. They cannot establish the necessary grounding connection for the alarm panel.