Each unit of A rating protects 3000 square feet.

• A. Each unit of A rating protects 3000 square feet.
• B. Each unit of A rating protects 1000 square feet.
• C. A rating is determined by the height of the ceiling.
• D. A rating applies only to Class A fires.

Answer: (A)

A rating unit is used to quantify how much area one rated element can protect, providing a consistent way to size protection for a given space. For this concept, each unit of A rating covers 3,000 square feet. That fixed coverage value lets you determine how many A-rating units are needed to protect a larger area simply by dividing the total square footage by 3,000.

So the correct idea is that one A rating unit protects 3,000 square feet, which is why the statement is right. If you claimed 1,000 square feet per unit, that would understate the coverage. If you thought the rating depended on ceiling height, you’d be mixing a geometric factor with a protection metric. And if you believed the rating only applies to Class A fires, you’d ignore that ratings are about coverage across the protected area, not limited to a single fire class. In practice, you’d use the 3,000 sq ft per unit rule to size the protection for any given space.