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A construction site has three buildings under construction with a total floor area of 45,000 square feet. How many Class A fire extinguishers with 4-A rating are minimally required?

Correct Answer

D) 6 extinguishers

Fire codes typically require one 4-A rated extinguisher per 3,000 square feet of floor area. With 45,000 square feet, the minimum requirement is 45,000÷3,000 = 15 units of A rating, which equals 6 extinguishers with 4-A rating (6×4=24>15).

Answer Options
A
8 extinguishers
B
12 extinguishers
C
10 extinguishers
D
6 extinguishers

Why This Is the Correct Answer

The correct answer is A (6 extinguishers) because fire codes require one unit of A rating per 3,000 square feet of floor area. With 45,000 square feet, you need 15 units of A rating minimum. Since each extinguisher has a 4-A rating, you need at least 6 extinguishers (6 × 4 = 24 units) to meet the 15-unit requirement. This is the minimum number that satisfies the code requirement.

Why the Other Options Are Wrong

Option B: 12 extinguishers

12 extinguishers would provide 48 units of A rating (12 × 4 = 48), which is more than triple the minimum requirement of 15 units and represents excessive over-compliance.

Option C: 10 extinguishers

8 extinguishers would provide 32 units of A rating (8 × 4 = 32), which exceeds the minimum requirement of 15 units and represents unnecessary over-compliance and additional cost.

Memory Technique

Remember '3-4 Rule': 3,000 sq ft per A unit, 4-A rating per extinguisher. Divide floor area by 3,000, then divide result by 4 to get minimum extinguishers needed.

Reference Hint

Florida Building Code Chapter 9 - Fire Protection Systems, or NFPA 10 Standard for Portable Fire Extinguishers

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