Master Plumber Practice Exam

Ferrous gas piping installed underground in exterior locations must have at least 1 foot of earth cover to ensure proper protection from external elements. This requirement is crucial because it helps to prevent mechanical damage to the piping from surface activities and provides a barrier against environmental factors such as moisture and temperature fluctuations, which can lead to corrosion. Adequate earth cover also helps to maintain the gas piping at a suitable temperature, supporting the overall safety and efficiency of the gas distribution system.

Other choices such as requiring double swing joints, condensation drip legs, or a specific number of elbows do not provide the essential protection that adequate earth cover offers. In contrast, those options relate to other aspects of gas piping installation and do not address the foundational requirement for burying ferrous materials underground. Ensuring that the piping is covered by at least 1 foot of earth is a fundamental safety measure that adheres to building codes and standards for underground gas pipelines.