Red Seal Plumbing Practice Exam

Fresh air supply must be installed at least 12 inches above finished ground level to ensure proper ventilation and prevent any potential fire hazards. Options A, B, and D are incorrect as they do not provide the necessary clearance for proper air flow and safety measures. Additionally, choosing an option that is too low may result in the fresh air supply getting covered or obstructed by debris or vegetation, making it less effective. Option C is also the most commonly recommended distance by building codes and industry standards. Therefore, 12 inches is the ideal height for an outside fresh air supply.