A 3-inch horizontal building drain is specified at 1/8 inch fall per foot. What fall is needed over 64 feet?
Correct Answer
A) 8 inches.
The required fall is rate times run: 64 feet at 1/8 inch per foot equals 8 inches.
Why This Is the Correct Answer
The required fall is rate times run: 64 feet at 1/8 inch per foot equals 8 inches.
Why the Other Options Are Wrong
Option B: 6 inches total.
6 inches total. is below the supported result for plumbing drainage slope calculation; it likely omits allowance, conversion, coverage, or final round-up.
Option C: 10 inches total.
10 inches total. is above the supported result for plumbing drainage slope calculation; it likely double-counts allowance, uses the wrong unit, or rounds too early.
Option D: 16 inches total.
16 inches total. is above the supported result for plumbing drainage slope calculation; it likely double-counts allowance, uses the wrong unit, or rounds too early.
Memory Technique
Checking Layout takeoff: count the condition before counting the package.
Reference Hint
Study anchor (closed-book): memorize Plumbing drainage slope calculation from California Plumbing Code, California Code of Regulations Title 24. / Title 24 California Plumbing Code horizontal drainage slope; know the rule or calculation trigger without relying on exam-room lookup.
More Class B Trade Questions
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