How many inches above the adjoining grade must equipment and appliances installed at grade level be supported?

The correct answer is that equipment and appliances installed at grade level must be supported at least 3 inches above the adjoining grade. This requirement ensures that the equipment is elevated enough to prevent potential damage from water, debris, or other environmental conditions that could affect performance and safety. Adequate clearance helps in maintaining equipment hygiene, facilitates easier maintenance and inspection, and reduces the risk of rust or corrosion that could result from prolonged contact with moisture or ground-level contaminants. This standard is often found in various building codes, ensuring compliance with safety and reliability in mechanical installations.