In the case of regulators installed in buildings and vented outside, the discharge outlet must be how far horizontally away or below any building opening?

The correct answer is three feet because this distance is established to ensure safety and prevent the accumulation of potentially harmful gases near building openings, such as windows, doors, or ventilation systems. When regulators vent outside, it is essential to direct any discharged gases away from areas where they could enter the building or come into contact with individuals. The three-foot distance helps to minimize the risk of gas exposure and maintains safe air quality inside the building.

Additionally, this regulation aligns with safety standards designed to protect occupants and ensure that gas does not accumulate in potentially hazardous areas. The specific requirement of three feet takes into consideration various factors, including wind patterns and potential sources of ignition, ensuring a robust safety buffer.