Drainage, Waste & VentQuestion 64 of 360
For a 1-1/2 inch trap arm, the maximum developed length from the trap weir to the vent is:
a.30 inches
b.60 inches
c.72 inches
d.42 inches
Explanation
Per the trap-to-vent distance table, a 1-1/2 inch trap arm may run a maximum developed length of 42 inches (3 feet 6 inches) to its vent. The 30 inch value is for a 1-1/4 inch arm, 60 inches is for a 2 inch arm, and 72 inches is for a 3 inch arm. Exceeding the limit risks self-siphonage of the trap seal.
Law Reference: 2022 California Plumbing Code (CPC) §1002.2Practice all 360 questions free — no signup required.
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