CSST shall not be connected to which of the following?

• A. exterior meters
• B. interior meters
• C. gas appliances
• D. vent stacks

Answer: (A)

CSST is a flexible gas piping material that must be installed in a protected, indoor environment and properly bonded to the building’s electrical grounding to guard against lightning and electrical arcing. Connecting CSST at an exterior gas meter places the piping in an outdoor, uncontrolled environment where it’s exposed to weather, moisture, physical damage, and conditions that can compromise the system. For safety and warranty reasons, CSST should not be connected at the exterior meter; the transition from meter to interior piping should occur inside, using appropriate rigid piping or approved fittings. Interior meters and gas appliances are typical points in the system, and vent stacks are part of the venting system, not a gas-supply connection.