Where must shut off valves be located when installing gas piping?

The correct choice emphasizes the importance of accessibility for shut-off valves in gas piping installations. Having shut-off valves located within 6 feet of the appliance ensures that they can be easily reached in case of an emergency or for maintenance. This proximity facilitates quick access, allowing for the immediate cessation of gas flow if necessary, thereby enhancing safety for users.

The requirement for valves to be accessible also aligns with safety codes and best practices in gas fitting to prevent long delays during critical situations. This is crucial not only for the safety of individuals but also for minimizing potential damage or hazards that could arise from a gas leak.

In contrast, options suggesting locations like at least 10 feet from the appliance, in the basement, or only outdoors do not meet the practical and safety standards necessary for effective gas management. Such placements could hinder timely access during emergencies, leading to an increased risk of accidents.