Core TradesQuestion 25 of 700
For a 2-inch fixture drain, what is a common MAXIMUM developed length of the trap arm (from the trap weir to the vent)?
a.3 feet
b.5 feet
c.8 feet
d.12 feet
Explanation
The plumbing code table generally allows a 2-inch trap arm up to about 5 feet of developed length before the vent, keeping the trap seal from being siphoned. 3 feet is overly restrictive for a 2-inch pipe, while 8 and 12 feet exceed the allowed length and risk self-siphonage.
Law Reference: 2025 CA Plumbing Code (CPC) Chapter 10 (Traps and Interceptors)Practice all 700 questions free — no signup required.
Related questions on this topic
- A device box contains four 12 AWG circuit conductors, two 12 AWG equipment grounding conductors, and one duplex receptacle. Using 2.25 cubic inches per 12 AWG conductor, what MINIMUM box volume is required?
- A 240-volt, 30-ampere dedicated circuit is wired with copper conductors. Under typical residential conditions, what is the MINIMUM copper conductor size that matches this 30-ampere circuit?
- In new dwelling construction, 15- and 20-ampere, 125-volt receptacles installed in normally accessible locations must generally be:
- The drainage fixture unit (DFU) value assigned to a plumbing fixture PRIMARILY represents:
- A horizontal branch drain must carry fixtures totaling 14 drainage fixture units. If a 2-inch pipe is rated for up to 6 DFU and a 3-inch pipe for up to 20 DFU, what is the MINIMUM pipe size?
- A cleanout on a 4-inch drain line must have a MINIMUM clearance in front of it for rodding of about:
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against California CSLB General Building (B) Trade Examination · How we review