Interstitial sensors must be tested _____.

• A. Weekly
• B. Annually
• C. Monthly
• D. Daily

Answer: (B)

Testing interstitial sensors on a regular basis ensures the leak-detection system that monitors the space between double walls remains capable of detecting a problem. These sensors must reliably trigger an alarm when the interstitial area is compromised, and the overall monitoring circuit—power, wiring, alarms—needs to be verified as functioning.

Annual testing is the standard because it balances reliability with practicality: sensors can drift or age, and a yearly functional check confirms they will respond as intended if a leak occurs, without requiring excessive downtime or maintenance. Manufacturer guidelines and regulatory requirements commonly specify this interval for ensuring continued protection.

Daily or weekly checks would be overly frequent for this purpose and add unnecessary downtime, while monthly checks are not the typical standard for interstitial sensors.