Equipment installed at grade level must be supported on a level concrete slab or other approved material extending above adjoining grade or suspended a minimum of how many inches above grade?

• A. Twelve Inches
• B. Six Inches
• C. Twenty-Four Inches
• D. Eighteen Inches

Answer: (B)

Mounting height rules for grade-level equipment are about ensuring a stable, dry, and accessible base. The base must be on a level concrete slab or approved material that extends above the surrounding ground, or the equipment must be suspended so it sits at least a certain distance above grade. The minimum distance is six inches. This clearance keeps moisture and ground contamination away from the equipment, helps with drainage and air circulation underneath, and makes service access easier. Larger clearances aren’t required by this rule, though some installations might call for more for other reasons.