What is the maximum length measurement allowed along the primary wall for sprinkler installation?

• A. 9 ft (2.7 m)
• B. 6 ft (1.8 m)
• C. 12 ft (3.7 m)
• D. 15 ft (4.6 m)

Answer: (A)

The main idea is how sprinklers are spaced along walls in low‑rise residential systems. When sprinklers are mounted on a wall, the spray patterns must overlap enough to keep the wall area protected. To ensure that points along the primary wall aren’t left uncovered, the distance between sprinklers along that wall cannot exceed nine feet. If you placed heads farther apart, the spray from each head wouldn’t reliably reach the far edge of the wall, creating unprotected zones near corners and along that wall.

So the maximum allowable length along the primary wall between sprinklers is nine feet. Smaller spacing, like six feet, would still meet coverage, but the question asks for the maximum. Distances such as twelve or fifteen feet would be too large and would risk inadequate coverage.