CPC · California Plumbing Code

Trap arm length, vent protection and change of direction

Q: Can I use the Table 1002.2 numbers for a toilet (water closet)?

No. Table 1002.2 explicitly excludes water closets and similar fixtures ; different trap/connection rules apply for WCs. See § 1002.2 .

Q: If my trap arm is 3 inches in diameter, how much direction change is allowed without a cleanout?

For trap arms 3 inches (80 mm) and larger , up to 135 degrees of change is allowed without a cleanout; otherwise the standard 90° limit applies for smaller trap arms ( § 1002.3 ) .

Q: If I have a long horizontal wet vent branch, do trap arm limits still apply?

Yes. Horizontal wet vent provisions (e.g., § 908.2 ) explicitly require trap arms to comply with Table 1002.2 limits; a wet vent does not relax those trap arm developed length limits .

Each fixture trap must be vented so the trap seal is protected. The CPC requires trap-arm developed lengths and minimums from Table 1002.2, limits on how much the trap arm can change direction without a cleanout (90° normally, 135° for ≥3" arms), and that the vent opening not be below the trap weir; see §§ 1002.1–1002.4 for full details. file

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

Each fixture trap must be protected from siphonage and backpressure by a vent pipe installed per the code (§ 1002.1) . The developed length of the trap arm (from the trap weir to the inner edge of the vent) must be within the distances in Table 1002.2 and never less than two times the diameter of the trap arm (§ 1002.2) . A trap arm may change horizontal direction without a cleanout up to 90 degrees (or 135 degrees for trap arms ≥ 3 inches in diameter) — see § 1002.3 . The vent opening into the soil/waste pipe (except for water closets and similar fixtures) must not be below the weir of the trap (§ 1002.4) .

The single most important rule: make sure each trap’s vent is close enough (per Table 1002.2) and not lower than the trap weir so the trap seal cannot be lost by siphonage or backpressure.

Requirements in detail

Key defined terms (first appearances are bolded)

Trap arm — the developed piping from the trap weir to the inner edge of the vent; its length is controlled by § 1002.2 .
Developed length — the measured (centerline) length along the trap arm from the trap weir to the vent connection; used in Table 1002.2 (§ 1002.2) .
Trap weir — the point at the trap where water overflows into the outlet; vent openings must not be below this per § 1002.4 .

How long may a trap arm be?

Use Table 1002.2. The table controls both the minimum distance (to avoid having the vent too close to the trap weir) and the maximum developed length (to assure adequate venting). The table applies to all fixtures except water closets and similar fixtures as noted in the table header (§ 1002.2) .

Trap arm pipe diameter (in)	Minimum distance trap to vent (in)	Maximum developed length (in)	Code Reference
1-1/4	2-1/2	30	§ 1002.2
1-1/2	3	42	§ 1002.2
2	4	60	§ 1002.2
3	6	72	§ 1002.2
4	8	120	§ 1002.2
Exceeding 4	2 × Diameter	120	§ 1002.2

Notes:

The table is explicitly titled HORIZONTAL LENGTHS OF TRAP ARMS (EXCEPT FOR WATER CLOSETS AND SIMILAR FIXTURES); water closets follow different requirements (§ 1002.2) .
The code also requires that the trap arm be at least two times the diameter of the trap arm (the minimum), even if that value is greater than the tabulated minimum (§ 1002.2) .

Change of direction (cleanout requirements)

A trap arm may change direction without a cleanout provided the total change does not exceed 90 degrees (horizontal changes must also comply with § 706.3) (§ 1002.3) .
Exception: for trap arms 3 inches (80 mm) in diameter and larger, the allowable change without a cleanout increases to 135 degrees; any change beyond that requires a cleanout (§ 1002.3) .
Horizontal changes must also meet the fit/turn standards in § 706.3 (see the code for allowable fittings and equivalent angles) .

Vent pipe opening relative to the trap

The vent pipe opening from a soil or waste pipe (except for water closets and similar fixtures) must not be below the weir of the trap; that is, the vent connection must enter above the trap weir to prevent flow into the vent that could compromise the trap seal (§ 1002.4) .

Interactions with wet venting, circuit venting and combination systems

Where horizontal wet vents or circuit vents are used, the trap arm length limits of Table 1002.2 still apply and the vent/connection location rules of § 1002.4 remain in force (see Sections 908.2 and 911.1 referencing Table 1002.2 and the trap arm limits) file.
Combination waste-and-vent or engineered vent systems have separate requirements (e.g., cleanouts, sizing, approvals) but still rely on the trap arm length/vent opening principles in Chapter 10; consult those sections when using alternative venting systems .

Exceptions & special cases

Water closets and "similar fixtures" are excluded from Table 1002.2; they are governed by other trap/vent provisions. The Table’s heading and § 1002.2 state that the table is "EXCEPT FOR WATER CLOSETS AND SIMILAR FIXTURES" (§ 1002.2) .
Trap arms ≥ 3 inches: permitted additional change of direction up to 135 degrees without a cleanout; beyond that, a cleanout is required (§ 1002.3) .
For engineered or combination vent systems, special sizing and approval requirements apply (see Sections 910 and 912) — these systems must still provide trap protection consistent with § 1002.1 and the trap arm limits where applicable file.
Minimum tailpiece length and trap placement rules (from Chapter 10, e.g., tailpiece ≤ 24 inches) may affect how the trap arm is developed and therefore should be considered when measuring developed length (see § 1001.2) .

Common mistakes

Assuming any horizontal run is acceptable: installers sometimes ignore Table 1002.2 — exceeding the maximum developed length can permit siphonage and is a code violation (§ 1002.2) .
Locating the vent below the trap weir: connecting the vent opening below the weir (or not verifying elevation) undermines the trap seal and violates § 1002.4 .
Counting bends incorrectly: summing multiple small angles incorrectly vs. using equivalent turns allowed by § 706.3 can lead to exceeding the permitted change of direction without a cleanout — remember the 90° (or 135° for ≥3") limit in § 1002.3 .
Forgetting the "two times the diameter" minimum: even if the table nominal minimum is smaller, the trap arm must be at least two times the diameter of the trap arm as required in § 1002.2 .
Applying Table 1002.2 to water closets: the table excludes water closets and similar fixtures; using those numbers for WCs is incorrect (§ 1002.2) .

Worked example — concrete scenario

Scenario: A lavatory with a 1-1/2 inch trap arm is installed. The trap outlet centerline to the vent's inner edge (developed length) will run 40 inches horizontally and include a 60° change in direction (one 45° plus one 15° equivalent).

Step 1 — Table limit: For 1-1/2 inch trap arm, Table 1002.2 lists maximum developed length = 42 inches and minimum = 3 inches; also the trap arm must be at least 2 × diameter = 3 inches (§ 1002.2) . The planned 40 inches is within the 42 in maximum.

Step 2 — Change of direction: Total change is 60°, which is less than the 90° allowed without a cleanout for trap arms under 3 inches (§ 1002.3) . No cleanout required for direction.

Step 3 — Vent opening elevation: Confirm the vent connects at or above the trap weir — it must not be below the weir per § 1002.4 .

Conclusion: The layout passes § 1002.2, § 1002.3, and § 1002.4 provided vent elevation is correct; if the run had been 45 inches, still acceptable (≤ 42 in? No — 45 exceeds 42 and would be noncompliant), so the maximum is the controlling limit.

Related provisions

§ 1001.2 — Trap location, tailpiece length and general trap requirements (tailpiece ≤ 24 inches) .
§ 706.3 — Horizontal changes of direction (applies to how turns count on trap arms) .
§ 908.2 — Horizontal wet venting for bathroom groups (explicitly references Table 1002.2 for trap arm lengths) .
§ 910.0 — Combination waste and vent system requirements (cleanouts, sizing, approvals) — interacts with trap/vent rules .
§ 911.1 — Circuit venting rules; trap arms connecting to circuit-vented branches must follow Table 1002.2 limits .
§ 1003.1–1003.3 — Trap construction and sizing requirements that work with trap arm/vent rules in Chapter 10 .

Code references

Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:

CPC § 1001.0 High relevance — show source text
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CHAPTER 10

TRAPS AND INTERCEPTORS

1001.0 General.

1001.1 Applicability. This chapter shall govern the materials, design, and installation of traps and interceptors.

1001.2 Where Required. Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap. This section shall not apply to fixtures with integral traps. Not more than one trap shall be permitted on a trap arm. Food waste disposers installed with a set of restaurant, commercial, or industrial sinks shall be connected to a separate trap.

Each domestic clothes washer and each laundry sink shall be connected to a separate and independent trap, except that a trap serving a laundry sink shall also be permitted to receive the waste from a clothes washer set adjacent to it.

The vertical distance between a fixture outlet and the trap weir shall be as short as practicable, but in no case shall the tailpiece exceed 24 inches (610 mm) in length.

One trap shall be permitted to serve a set of not more than three single compartment sinks or laundry sinks of the same depth or three lavatories immediately adjacent to each other and in the same room where the waste outlets are not more than 30 inches (762 mm) apart, and the trap is centrally located where three compartments are installed.

1002.0 Traps Protected by Vent Pipes.

1002.1 Vent Pipes. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage, backpressure, and air circulation shall be assured throughout the drainage system using a vent pipe installed in accordance with the requirements of this code.

1002.2 Fixture Traps. Each fixture trap shall have a protecting vent so located that the developed length of the trap arm from the trap weir to the inner edge of the vent shall be within the distance given in Table 1002.2 but in no case less than two times the diameter of the trap arm. 1002.3 Change of Direction. A trap arm shall be permitted to change direction without the use of a cleanout where such change of direction does not exceed 90 degrees (1.57 rad). Horizontal changes in the direction of trap arms shall be in accordance with Section 706.3.

Exception: For trap arms, 3 inches (80 mm) in diameter and larger, the change of direction shall not exceed 135 degrees (2.36 rad) without the use of a cleanout. 1002.4 Vent Pipe Opening. The vent pipe opening from soil or waste pipe, except for water closets and similar fixtures, shall not be below the weir of the trap.

1003.0 Traps – Described. 1003.1 General Requirements. Each trap, except for traps within an interceptor or similar device shall be selfcleaning. Traps for bathtubs, showers, lavatories, sinks, laun

dry sinks, floor drains, urinals, drinking fountains, dental units, and similar fixtures shall be of standard design, weight and shall be of ABS, cast-brass, cast-iron, lead, PP, PVC, or other approved material. An exposed and readily accessible drawn-copper alloy tubing trap, not less than 17 B & S Gauge (0.045 inch) (1.143 mm), shall be permitted to be used on fixtures discharging domestic sewage.

Exception s :
CPC § 1002.2 High relevance — show source text
1002.2 Fixture Traps. Each fixture trap shall have a protecting vent so located that the developed length of the trap arm from the trap weir to the inner edge of the vent shall be within the distance given in Table 1002.2 but in no case less than two times the diameter of the trap arm. 1002.3 Change of Direction. A trap arm shall be permitted to change direction without the use of a cleanout where such change of direction does not exceed 90 degrees (1.57 rad). Horizontal changes in the direction of trap arms shall be in accordance with Section 706.3.

Exception: For trap arms, 3 inches (80 mm) in diameter and larger, the change of direction shall not exceed 135 degrees (2.36 rad) without the use of a cleanout. 1002.4 Vent Pipe Opening. The vent pipe opening from soil or waste pipe, except for water closets and similar fixtures, shall not be below the weir of the trap.

1003.0 Traps – Described. 1003.1 General Requirements. Each trap, except for traps within an interceptor or similar device shall be selfcleaning. Traps for bathtubs, showers, lavatories, sinks, laun

dry sinks, floor drains, urinals, drinking fountains, dental units, and similar fixtures shall be of standard design, weight and shall be of ABS, cast-brass, cast-iron, lead, PP, PVC, or other approved material. An exposed and readily accessible drawn-copper alloy tubing trap, not less than 17 B & S Gauge (0.045 inch) (1.143 mm), shall be permitted to be used on fixtures discharging domestic sewage.

Exception s :

(1) Drawn-copper alloy tubing traps shall not be used for urinals. Each trap shall have the manufacturer’s name stamped legibly in the metal of the trap, and each tubing trap shall have the gauge of the tubing in addition to the manufacturer’s name. A trap shall have a smooth and uniform interior waterway.

(2) [HCD 1 & HCD 2] Non-water supplied urinals conform- ing to ASME A112.19.19-2016, Standard for Vitreous China Nonwater Urinals, or reference standards in Table 1701.1 for non-vitreous ceramic or plastic urinal fixtures.

TABLE 1002.2

HORIZONTAL LENGTHS OF TRAP ARMS (EXCEPT FOR WATER CLOSETS AND SIMILAR FIXTURES) [1, 2, 3]

TRAP ARM PIPE
DIAMETER (inches) DISTANCE TRAP TO
VENT MINIMUM
(inches) LENGTH MAXIMUM
(inches)

11⁄4 21⁄2 30

11⁄2 3 42

2 4 60

3 6 72

4 8 120

Exceeding 4 2 x Diameter 120

For SI units: 1 inch = 25.4 mm
CPC § 907.2 High relevance — show source text
907.2 Yoke Vent. The yoke vent connection to the vent stack shall be placed not less than 42 inches (1067 mm) above the floor level, and the yoke vent connection to the drainage stack shall be using a wye-branch fitting placed below the lowest drainage branch connection serving that floor.

908.0 Wet Venting. 908.1 Vertical Wet Venting. Wet venting is limited to vertical drainage piping receiving the discharge from the trap arm of one and two fixture unit fixtures that also serves as a vent not exceeding four fixtures. Wet-vented fixtures shall be within the same story; provided, further, that fixtures with a continuous vent discharging into a wet vent shall be within the same story as the wet-vented fixtures. No wet vent shall exceed 6 feet (1829 mm) in developed length. 908.1.1 Size. The vertical piping between two consecutive inlet levels shall be considered a wet-vented sec tion. Each wet-vented section shall be not less than one pipe size exceeding the required minimum waste pipe size of the upper fixture or shall be one pipe size exceeding the required minimum pipe size for the sum of the fixture units served by such wet-vented section, whichever is larger, but in no case less than 2 inches (50 mm) in diameter. 908.1.2 Vent Connection. Common vent sizing shall be the sum of the fixture units served but, in no case,

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smaller than the minimum vent pipe size required for a fixture served, or by Section 904.0. 908.2 Horizontal Wet Venting for a Bathroom Group. A bathroom group located on the same floor level shall be permitted to be vented by a horizontal wet vent where all of the conditions of Section 908.2.1 through Section 908.2.5 are met.

908.2.1 Vent Connection. The dry vent connection to the wet vent shall be an individual vent for the bidet, shower, or bathtub. One or two vented lavatory(s) shall be permitted to serve as a wet vent for a bathroom group. Only one wet-vented fixture drain or trap arm shall discharge upstream of the dry-vented fixture drain connection. Dry vent connections to the horizontal wet vent shall be in accordance with Section 905.2 and Section

905.3.

908.2.2 Size. The wet vent shall be sized based on the fixture unit discharge into the wet vent. The wet vent shall be not less than 2 inches (50 mm) in diameter for 4 drainage fixture units (dfu) or less, and not less than 3 inches (80 mm) in diameter for 5 dfu or more. The dry vent shall be sized in accordance with Table 702.1 and Table 703.2 based on the total fixture units discharging into the wet vent.

908.2.3 Trap Arm. The length of the trap arm shall not exceed the limits in Table 1002.2. The trap size shall be in accordance with Section 1003.3. The vent pipe opening from the horizontal wet vent, except for water closets and similar fixtures, shall not be below the weir of the trap.
CPC § 911.3 High relevance — show source text
911.3 Relief Vent . . . . . . . . . . . . . . . . . .192

911.4 Slope and Size of Horizontal Branch . . . . . . . . . . . . . . . . . . . . .192

911.5 Additional Fixtures . . . . . . . . . . . .192

912.0 Engineered Vent System . . . . . . .192

912.1 General . . . . . . . . . . . . . . . . . . . . .192

912.2 Minimum Requirements . . . . . . . .192

CHAPTER 10 TRAPS AND

INTERCEPTORS . . . . . . . . . . . . .193

1001.0 General . . . . . . . . . . . . . . . . . . . . .195

1001.1 Applicability . . . . . . . . . . . . . . . . . .195

1001.2 Where Required . . . . . . . . . . . . . .195

1002.0 Traps Protected by Vent Pipes . .195

1002.1 Vent Pipes . . . . . . . . . . . . . . . . . .195

1002.2 Fixture Traps . . . . . . . . . . . . . . . .195

1002.3 Change of Direction . . . . . . . . . . .195

1002.4 Vent Pipe Opening . . . . . . . . . . . .195

1003.0 Traps – Described . . . . . . . . . . . .195

1003.1 General Requirements . . . . . . . . .195

Table 1002.2 Horizontal Lengths of Trap Arms . . . . . . . . . . . . . . . . . . . . . . .195

1003.2 Slip Joint Fittings . . . . . . . . . . . . .195

1003.3 Size . . . . . . . . . . . . . . . . . . . . . . . .195

1004.0 Traps . . . . . . . . . . . . . . . . . . . . . .196

1004.1 Prohibited . . . . . . . . . . . . . . . . . . .196

1004.2 Movable Parts . . . . . . . . . . . . . . . .196

1005.0 Trap Seals . . . . . . . . . . . . . . . . . .196

1005.1 General . . . . . . . . . . . . . . . . . . . . .196

1006.0 Floor Drain Traps . . . . . . . . . . . . .196

1006.1 General . . . . . . . . . . . . . . . . . . . . .196

1007.0 Trap Seal Protection . . . . . . . . . . .196

1007.1 General . . . . . . . . . . . . . . . . . . . . .196

1007.2 Trap Seal Primers . . . . . . . . . . . .196

1008.0 Building Traps . . . . . . . . . . . . . . . .196

1008.1 General . . . . . . . . . . . . . . . . . . . . .196
CPC § 206.0 Medium relevance — show source text
and connections)

– D –

DEPARTMENT, DEFINITION . . . . . . . . . . . . . . . . . . . . . 206.0

DESIGN FLOOD ELEVATION . . . . . . . . . . . . . .206.0, 301.4

DEVELOPED LENGTH

Bar and fountain sink trap . . . . . . . . . . . . . . . . . . .801.4

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206.0

DWV piping . . . . . . . . . . . . . . . . . . . . . .707.4, 710.13.2

Indirect waste piping . . . . . . . . . . . . . . . . . . . . . .801.3.1

Trap arm . . . . . . . . . . . . . . . . . . . .1002.2, Table 1002.2

Water supply piping . . . . . . . . . .610.9, A 104.4, A 107.2

Wet vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .908.1

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INDEX

DIALYSIS WATER-DISTRIBUTION SYSTEMS . . . . . . . .614.0

DIELECTRIC INSULATORS . . . . . . . . . . . . . . . . . . . . .507.1

DISHWASHING MACHINES . . . . . . . . . . . . . . . . . . . .414.0

Air gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .807.3 Approved standards . . . . . . . . . . . . . . . . . . . . . . .414.1 Backflow protection . . . . . . . . . . . . . . . . . . . . . . . .414.2 Discharge, drainage . . . . . . . . . . .414.3, 807.3, 1014.3.2 Drainage discharge, prohibited . . . . . . . .419.2, 1014.1.3 Drainage fixture unit (DFU) . . . . . . . . . . . . .Table 702.1 Energy efficiency . . . . . . . . . . . . . . . . . . . . . . . .L 403.1 Flexible connector length . . . . . . . . . . . . . . . . . . .604.12 Water supply fixture units (WSFU) . . . . .Table 610.3, Table A 103.1, Table C 303.2

DISINFECTED TERTIARY RECYCLED

WATER
CPC § 1.11.0. Medium relevance — show source text
1 Exception 2_||||X|X|||||||||||||||||||| |1010.2|||||||||||||||||||X|||||| |1010.3|||||||||||||||||||X|||||| |1010.4|||||||||||||||||||X|||||| |1010.5|||||||||||||||||||X|||||| |1014.1A, B, C||||||||||X|X|X|X|X|X|||||||||| |1015.5||||||||||X|X|X|X|X|X|||||||||| |1015.6||||||||||X|X|X|X|X|X||||||||||

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

2025 CALIFORNIA PLUMBING CODE 193

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CHAPTER 10

TRAPS AND INTERCEPTORS

1001.0 General.

1001.1 Applicability. This chapter shall govern the materials, design, and installation of traps and interceptors.

1001.2 Where Required. Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap. This section shall not apply to fixtures with integral traps. Not more than one trap shall be permitted on a trap arm. Food waste disposers installed with a set of restaurant, commercial, or industrial sinks shall be connected to a separate trap.

Each domestic clothes washer and each laundry sink shall be connected to a separate and independent trap, except that a trap serving a laundry sink shall also be permitted to receive the waste from a clothes washer set adjacent to it.

The vertical distance between a fixture outlet and the trap weir shall be as short as practicable, but in no case shall the tailpiece exceed 24 inches (610 mm) in length.

One trap shall be permitted to serve a set of not more than three single compartment sinks or laundry sinks of the same depth or three lavatories immediately adjacent to each other and in the same room where the waste outlets are not more than 30 inches (762 mm) apart, and the trap is centrally located where three compartments are installed.

1002.0 Traps Protected by Vent Pipes.

1002.1 Vent Pipes. Each plumbing fixture trap, except as otherwise provided in this code, shall be protected against siphonage, backpressure, and air circulation shall be assured throughout the drainage system using a vent pipe installed in accordance with the requirements of this code.
CPC § 910.7 Medium relevance — show source text
910.7 Fixtures. No water closet or urinal shall be installed on such a system. Other one, two, or three unit fixtures remotely located from the sanitary system and adjacent to a combination waste and vent system shall be permitted to be connected to such system in the conventional manner by means of waste and vent pipes of regular sizes, providing that the two pipe size increase required in Section 910.4 is based on the total fixture unit load connected to the system.

See Appendix B of this code for explanatory notes on the design of combination waste and vent systems.

911.0 Circuit Venting. 911.1 Circuit Vent Permitted. A maximum of eight flooroutlet water closets, showers, bathtubs, or floor drains con

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VENTS

nected to a horizontal branch shall be permitted to be circuit vented. Each trap arm shall connect horizontally to the horizontal branch being circuit vented in accordance with Table 1002.2. The horizontal branch shall be classified as a drain and a vent from the most downstream trap arm connection to the most upstream trap arm connection to the horizontal branch.

Exception: Back-outlet and wall-hung water closets shall be permitted to be circuit vented provided that no floor-outlet fixtures are connected to the same horizontal branch. Backoutlet and wall-hung water closets shall connect horizontally to the horizontal circuit vented drain.

911.2 Circuit Vent Size and Connection. The circuit vent size shall be in accordance with Table 703.2 according to the number of circuit vented fixtures connected to the horizontal branch but shall be not less than 2 inches (50 mm) in diameter. The vent shall connect to the horizontal branch on the vertical between the two most upstream trap arms. The circuit vent pipe shall not receive the discharge of soil or

waste.

911.2.1 Multiple Circuit Vents. When multiple circuit vents are interconnected according to Section 911.4.1, each individual circuit vent shall be sized according to Section 911.2. The vent pipe connecting each circuit vent shall be sized according to Table 703.2.

911.3 Relief Vent. A 2 inch (50 mm) relief vent shall be provided for circuit-vented horizontal branches receiving the discharge of four or more water closets when connecting to a drainage stack that receives the discharge of soil or waste from upper horizontal branches.

911.3.1 Connection and Installation. The relief vent

shall connect to the horizontal branch between the stack and the most downstream trap arm of the circuit vent. The relief vent shall be installed on the vertical to the

horizontal branch.

911.3.2 Fixture Drain. The relief vent is permitted to serve as a fixture drain. Fixtures discharging to a relief vent shall be one or two fixture unit fixtures but shall not

exceed a total of 4 fixture units.

911.4 Slope and Size of Horizontal Branch. The vented section of the horizontal branch shall be uniformly sloped and not more than 1 inch per foot (83.3 mm/m). The entire length of the vented section of the horizontal branch shall be sized for the total drainage discharge to the branch according to Table 703.2.
CPC § 910.0 Medium relevance — show source text
910.0 Combination Waste and Vent Systems. 910.1 Where Permitted. Combination waste and vent systems shall be permitted where structural conditions preclude the installation of conventional systems as otherwise prescribed by this code. 910.2 Approval. Construction documents for each combination waste and vent system shall first be approved by the Authority Having Jurisdiction before a portion of such system is installed.

910.3 Vents. Each combination waste and vent system, as defined in Chapter 2, shall be provided with a vent or vents adequate to ensure free circulation of air. A branch exceeding 15 feet (4572 mm) in length shall be separately vented in an approved manner. The area of a vent installed in a combination waste and vent system shall be not less than one-half the inside cross-sectional area of the drainpipe served. The vent connection shall be downstream of the uppermost fixture. 910.4 Connections and Size. Branches serving traps shall connect to the main line at an angle not exceeding 2 percent. Each waste pipe and each trap in such a system shall be not less than two pipe sizes exceeding the sizes required by Chapter 7 of this code, and not less than two pipe sizes exceeding a fixture tailpiece or connection. 910.5 Vertical Waste Pipe. No vertical waste pipe shall be used in such a system, except the tailpiece or connection between the outlet of a plumbing fixture and the trap. Such tailpieces or connections shall be as short as possible, and in no case shall exceed 2 feet (610 mm).

Exception: Branch lines shall be permitted to have 45 degree (0.79 rad) vertical offsets.

910.6 Cleanouts. An accessible cleanout shall be installed in each vent for the combination waste and vent system. Cleanouts shall not be required on a wet-vented branch serving a single trap where the fixture tailpiece or connection is not less than 2 inches (50 mm) in diameter and provides ready access for cleaning through the trap.

910.7 Fixtures. No water closet or urinal shall be installed on such a system. Other one, two, or three unit fixtures remotely located from the sanitary system and adjacent to a combination waste and vent system shall be permitted to be connected to such system in the conventional manner by means of waste and vent pipes of regular sizes, providing that the two pipe size increase required in Section 910.4 is based on the total fixture unit load connected to the system.

See Appendix B of this code for explanatory notes on the design of combination waste and vent systems.

911.0 Circuit Venting. 911.1 Circuit Vent Permitted. A maximum of eight flooroutlet water closets, showers, bathtubs, or floor drains con

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nected to a horizontal branch shall be permitted to be circuit vented. Each trap arm shall connect horizontally to the horizontal branch being circuit vented in accordance with Table 1002.2. The horizontal branch shall be classified as a drain and a vent from the most downstream trap arm connection to the most upstream trap arm connection to the horizontal branch.

Exception: Back-outlet and wall-hung water closets shall be permitted to be circuit vented provided that no floor-outlet fixtures are connected to the same horizontal branch. Backoutlet and wall-hung water closets shall connect horizontally to the horizontal circuit vented drain.
CPC § 904.0. Medium relevance — show source text
VENTS

smaller than the minimum vent pipe size required for a fixture served, or by Section 904.0. 908.2 Horizontal Wet Venting for a Bathroom Group. A bathroom group located on the same floor level shall be permitted to be vented by a horizontal wet vent where all of the conditions of Section 908.2.1 through Section 908.2.5 are met.

908.2.1 Vent Connection. The dry vent connection to the wet vent shall be an individual vent for the bidet, shower, or bathtub. One or two vented lavatory(s) shall be permitted to serve as a wet vent for a bathroom group. Only one wet-vented fixture drain or trap arm shall discharge upstream of the dry-vented fixture drain connection. Dry vent connections to the horizontal wet vent shall be in accordance with Section 905.2 and Section

905.3.

908.2.2 Size. The wet vent shall be sized based on the fixture unit discharge into the wet vent. The wet vent shall be not less than 2 inches (50 mm) in diameter for 4 drainage fixture units (dfu) or less, and not less than 3 inches (80 mm) in diameter for 5 dfu or more. The dry vent shall be sized in accordance with Table 702.1 and Table 703.2 based on the total fixture units discharging into the wet vent.

908.2.3 Trap Arm. The length of the trap arm shall not exceed the limits in Table 1002.2. The trap size shall be in accordance with Section 1003.3. The vent pipe opening from the horizontal wet vent, except for water closets and similar fixtures, shall not be below the weir of the trap.

908.2.4 Water Closet. The water closet fixture drain or trap arm connection to the wet vent shall be downstream of fixture drain or trap arm connections to the horizontal wet vent.

908.2.5 Additional Fixtures. Additional fixtures shall discharge downstream of the wet vent system and be conventionally vented. Only the fixtures within the bathroom group shall connect to the wet-vented horizontal branch.

909.0 Special Venting for Island Fixtures. 909.1 General. Traps for island sinks and similar equipment shall be roughed in above the floor and shall be permitted to be vented by extending the vent as high as possible, but not less than the drainboard height and then returning it downward and connecting it to the horizontal sink drain immediately downstream from the vertical fixture drain. The return vent shall be connected to the horizontal drain through a wyebranch fitting and shall, in addition, be provided with a foot vent taken off the vertical fixture vent by means of a wye branch immediately below the floor and extending to the nearest partition and then through the roof to the open air, or shall be permitted to be connected to other vents at a point not less than 6 inches (152 mm) above the flood-level rim of the fixtures served. Drainage fittings shall be used on the vent below the floor level, and a slope of not less than [1] ⁄ 4 inch per foot (20.8 mm/m) back to the drain shall be maintained. The return bend used under the drainboard shall be a one-piece

TRAP ARM PIPE DIAMETER (inches)	DISTANCE TRAP TO VENT MINIMUM (inches)	LENGTH MAXIMUM (inches)
11⁄4	21⁄2	30
11⁄2	3	42
2	4	60
3	6	72
4	8	120
Exceeding 4	2 x Diameter	120

CPC § 1207.6 Medium relevance — show source text

TABLE 1207.6—ELECTROCHEMICAL ESS TECHNOLOGY-SPECIFIC REQUIREMENTS	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
COMPLIANCE REQUIREDb	COMPLIANCE REQUIREDb	BATTERY TECHNOLOGY	BATTERY TECHNOLOGY	BATTERY TECHNOLOGY	BATTERY TECHNOLOGY	BATTERY TECHNOLOGY	BATTERY TECHNOLOGY	OTHER ESS AND BATTERY TECHNOLOGIESb	CAPACITOR ESSb
Feature	Section	Lead- acid	Nickel cadmium (Ni-Cd), nickel-metal hydride (Ni-MH) and nickel zinc (Ni-Zn)	Zinc- manganese dioxide (Zn-MnO2)	Lithium-ion	Flow	Sodium nickel chloride	Sodium nickel chloride	Sodium nickel chloride
Exhaust ventilation	1207.6.1	Yes	Yes	Yes	No	Yes	No	Yes	Yes
Explosion control	1207.6.3	Yesa	Yesa	Yes	Yes	No	Yes	Yes	Yes
Safety caps	1207.6.4	Yes	Yes	No	No	No	No	Yes	Yes
Spill control and neutralization	1207.6.2	Yesc	Yesc	Yesf	No	Yes	No	Yes	Yes
Thermal runaway	1207.6.5	Yesd	Yes	Yese	Yese	No	Yes	Yese	Yes
a. Not required for lead-acid and nickel-cadmium batteries at facilities under the exclusive control of communications utilities that comply with NFPA 76 and operate at less than 50 VAC and 60 VDC. b. Protection shall be provided unless documentation acceptable to the fire code official is provided in accordance with Section 104.2.2 that provides justification why the protection is not necessary based on the technology used. c. Applicable to vented-type (i.e., flooded) nickel-cadmium and lead-acid batteries. d. Not required for vented-type (i.e., flooded) batteries. e. The thermal runaway protection is permitted to be part of a battery management system that has been evaluated with the battery as part of the evaluation to UL 1973. f. Not required for batteries with jelled electrolyte.	a. Not required for lead-acid and nickel-cadmium batteries at facilities under the exclusive control of communications utilities that comply with NFPA 76 and operate at less than 50 VAC and 60 VDC. b. Protection shall be provided unless documentation acceptable to the fire code official is provided in accordance with Section 104.2.2 that provides justification why the protection is not necessary based on the technology used. c.

CPC § 8.2 Medium relevance — show source text
Exception: Outdoor systems containing Group A1 refrigerant shall be permitted to discharge at any elevation where the point of discharge is located in an access-controlled area accessible to authorized personnel only.

(2) The point of vent discharge shall be located not less than 20 feet (6096 mm) from windows, building ventilation openings, pedestrian walkways, or building exits.

(3) For heavier-than-air refrigerants, the point of vent discharge shall be located not less than 20 feet (6096 mm) horizontally from below-grade walkways, entrances, pits, or ramps where a release of the entire system charge into such a space would yield a concentration of refrigerant in excess of the RCL. The direct discharge of a relief vent into enclosed outdoor spaces, such as a courtyard with walls on all sides, shall not be permitted where a release of the entire system charge into such a space would yield a concentration of refrigerant in excess of the RCL. The volume for the refrigerant concentration calculation shall be determined using the gross area of the space and a height of 8.2 feet (2499 mm), regardless of the actual height of the enclosed space.

(4) The termination point of a vent discharge line shall be made in a manner that prevents discharged refrigerant from spraying directly onto personnel that are capable of being in the vicinity.

(5) The termination point of vent discharge lines shall be made in a manner that prevents foreign material or debris from entering the discharge piping.

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REFRIGERATION

(6) Relief vent lines that terminate vertically upward and are subject to moisture entry shall be provided with a drip pocket having a length of not less than 24 inches (610 mm) and having the size of the vent discharge pipe. The drip pocket shall be installed to extend below the first change in vent pipe direction and shall be fitted with a valve or drain plug to permit removal of accumulated moisture. [ASHRAE 15:9.7.8.2]

1112.11.3 Internal Relief. Pressure-relief valves

designed to discharge from a higher-pressure vessel into a lower pressure vessel internal to the system shall comply with the following:

(1) The pressure-relief valve that protects the higherpressure vessel shall be selected to deliver capacity in accordance with Section 1113.5 without exceed ing the maximum allowable working pressure of the higher-pressure vessel accounting for the change in mass flow capacity due to the elevated backpressure.

(2) The capacity of the pressure-relief valve protecting the part of the system receiving a discharge from a pressure-relief valve protecting a higher-pressure vessel shall be not less than the sum of the capacity required in Section 1113.5 plus the mass flow capacity of the pressure-relief valve discharging into that part of the system.

(3) The design pressure of the body of the relief valve used on the higher-pressure vessel shall be rated for operation at the design pressure of the higher-pressure vessel in both pressure-containing areas of the valve. [ASHRAE 15:9.7.8.3]

1112.11.4 Discharge Location, Special Require- ments. Additional requirements for pressure relief device discharge location and allowances shall apply for specific refrigerants in accordance with Section 1112.11.4.1. [ASHRAE 15:9.7.8.4]
CPC § 11.0 Medium relevance — show source text
11.0 - 1.11.11_|||X|||||||||||||||||||||| |1.13.0||||||||||||||||||||X||||| |Division II - Scope and
Administration||||||||||||||||||||||||| |101.0||||||||||X|X|X||X|X|||||||||| |102.0||||||||||X|X|X||X|X|||||||||| |103.0||||||||||X|X|X||X|X|||||||||| |104.2 Items 1 & 2||||X|X|||||||||||||||||||| |104.3.1||||||||||X|X|X||X|X|||||||||| |104.4.3.1|X|||||||||||||||||||||||| |105.0||||||||||X|X|X||X|X||||||||||

This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

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CHAPTER 1

ADMINISTRATION

DIVISION I

CALIFORNIA ADMINISTRATION

1.1.0 General.

1.1.1 Title. These regulations shall be known as the Califor- nia Plumbing Code, may be cited as such and will be referred to herein as “this code.” The California Plumbing Code is Part 5 of thirteen parts of the official compilation and publi- cation of the adoption, amendment, and repeal of plumbing regulations to the California Code of Regulations, Title 24, also referred to as the California Building Standards Code. This part incorporates by adoption the 2024 Uniform Plumb- ing Code of the International Association of Plumbing and Mechanical Officials with necessary California amendments.

1.1.2 Purpose. The purpose of this code is to establish the minimum requirements to safeguard the public health, safety and general welfare through structural strength, means of egress facilities, stability, access to persons with disabilities, sanitation, adequate lighting and ventilation, and energy con- servation; safety to life and property from fire and other haz- ards attributed to the built environment; and to provide safety to fire fighters and emergency responders during emergency operations.

1.1.3 Scope. The provisions of this code shall apply to the construction, alteration, movement, enlargement, replace- ment, repair, equipment, use and occupancy, location, main- tenance, removal, and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures throughout the State of California.

Frequently asked questions

Can I use the Table 1002.2 numbers for a toilet (water closet)?

No. Table 1002.2 explicitly excludes water closets and similar fixtures; different trap/connection rules apply for WCs. See § 1002.2 .

If my trap arm is 3 inches in diameter, how much direction change is allowed without a cleanout?

For trap arms 3 inches (80 mm) and larger, up to 135 degrees of change is allowed without a cleanout; otherwise the standard 90° limit applies for smaller trap arms (§ 1002.3) .

What if the developed length I measure includes vertical offsets?

Developed length is measured along the centerline of the trap arm from the trap weir to the inner edge of the vent; vertical offsets are included in developed length. Use that developed length to compare with Table 1002.2 limits in § 1002.2 .

Is it acceptable to connect the vent at a point below the trap weir if I add a check or device?

No. The code plainly requires the vent pipe opening from soil or waste pipe (except WC) to not be below the weir of the trap — devices that create flow into the vent do not change this requirement (§ 1002.4) .

If I have a long horizontal wet vent branch, do trap arm limits still apply?

Yes. Horizontal wet vent provisions (e.g., § 908.2) explicitly require trap arms to comply with Table 1002.2 limits; a wet vent does not relax those trap arm developed length limits .

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California Plumbing Code