Drainage, Waste & VentQuestion 120 of 360
A horizontal branch serves two water closets (3 DFU each), two lavatories (1 DFU each), and two showers (2 DFU each). What is the minimum branch size?
a.2 inch
b.4 inch
c.1-1/2 inch
d.3 inch
Explanation
The load is (2 x 3) + (2 x 1) + (2 x 2) = 6 + 2 + 4 = 12 DFU. A 3 inch branch carries up to 20 DFU and allows a maximum of two water closets, so it fits both the 12 DFU load and the two closets. A 2 inch branch (6 DFU) and 1-1/2 inch branch (3 DFU) are undersized, and a 4 inch branch is larger than needed here.
Law Reference: 2022 California Plumbing Code (CPC) §703.0 (Table 703.1)Practice all 360 questions free — no signup required.
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