Drainage, Waste & VentQuestion 89 of 360
A horizontal branch serves two lavatories (1 DFU each), one kitchen sink (2 DFU), and one bathtub (2 DFU). What is the total DFU and minimum branch size?
a.6 DFU, 2 inch branch
b.4 DFU, 1-1/2 inch branch
c.8 DFU, 3 inch branch
d.6 DFU, 1-1/2 inch branch
Explanation
The load is 1 + 1 + 2 + 2 = 6 DFU. A 2 inch horizontal branch is rated for exactly 6 DFU, so it is the minimum size. A 1-1/2 inch branch is limited to 3 DFU and is undersized, while a 3 inch branch is larger than needed for 6 DFU.
Law Reference: 2022 California Plumbing Code (CPC) §703.0 (Table 703.1)Practice all 360 questions free — no signup required.
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