CMC · California Mechanical Code

How are relief devices sized and what rating formulas apply?

If a vessel needs protection, the code says first determine the required relieving flow per ASHRAE 15 (adopted in the CMC). Then: pick a pressure‑relief valve sized to ASME BPVC rules (§1112.13) or, for rupture disks and fusible plugs, size them using the CMC formulas in §1112.14 (C = 0.64·P1·d^2; solve for d = 1.25·√(C/P1)). Always confirm piping, backpressure and inlet area meet the CMC requirements so the installed device can actually deliver the required flow.

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Last reviewed: July 6, 2026

What the code requires — plain English

Pressure-relief devices are sized two ways in the CMC: (1) pressure‑relief valves are rated and sized in accordance with the ASME Boiler & Pressure Vessel Code (as required by § 1112.13) and (2) rupture members and fusible plugs that discharge to atmosphere are sized using the CMC’s numeric rating formulas in § 1112.14. The minimum required relieving capacity for a pressure vessel is set by ASHRAE 15 and adopted into the CMC via § 1113.5.

The single most important rule: size relief devices to meet the required discharge capacity (per ASHRAE 15 via § 1113.5) and use § 1112.13 for pressure‑relief valves and § 1112.14 for rupture members/fusible plugs to compute the device rating.

Requirements in detail

Which standard controls the required relieving capacity

  • The CMC adopts ASHRAE 15 for the minimum required discharge capacity of pressure‑relief devices for refrigeration pressure vessels: § 1113.5 (discharge capacity determined in accordance with ASHRAE 15).

Rating rules for pressure‑relief valves (valved devices)

  • The rated discharge capacity of a pressure‑relief valve (expressed in pounds of air per minute or kg/s) must be determined in accordance with ASME BPVC Section VIII.1, per § 1112.13. Also, piping and fittings between the valve and the protected part must have at least the inlet area of the valve.

Rating formulas for rupture members and fusible plugs

  • For rupture members and fusible plugs discharging to atmosphere under critical flow, the CMC provides explicit formulas in § 1112.14 to compute the rated discharge capacity (C) or the minimum required smallest diameter (d). The code gives the equations and definitions for the variables (including how to compute P1 for rupture members and for fusible plugs).

Key formulas (as expressed in the CMC):

  • C = 0.64 × P1 × d^2 [Equation 1112.14(1)]
  • d = 1.25 × sqrt( C / P1 ) [Equation 1112.14(2)]

Where the variables are defined in the section:

  • C = rated discharge capacity (mass flow of air), in pounds per minute (or converted to SI).
  • d = the smallest internal diameter of the inlet, retaining flanges, fusible plug or rupture member, in inches.
  • P1 = depends on device type:
    • For rupture members: P1 = (rated pressure in psig × 1.1) + 14.7 psia (see § 1112.14).
    • For fusible plugs: P1 = the absolute saturation pressure at the plug’s stamped melting temperature (or the refrigerant’s critical pressure, whichever is smaller).

Note: the code also provides the SI conversion factor (1 lb/min ≈ 0.00756 kg/s).

Decision‑relevant dimensions and values (quick reference)

Dimension / value What it is Units Code reference
C Required or rated discharge capacity (mass flow of air) lb/min (SI: kg/s) § 1112.14, § 1113.5
d Smallest internal diameter (inlet, flanges, plug, rupture member) inches § 1112.14
P1 Pressure used in rating formulas (absolute, psia) psia § 1112.14 (definitions for rupture member / fusible plug)
Valve rating method Pressure‑relief valve capacity per ASME BPVC Section VIII.1 — § 1112.13
Minimum discharge capacity source Determines required C for a vessel — § 1113.5 (ASHRAE 15)
Discharge piping area Pipe/fittings must have not less than valve inlet area — § 1112.13

Exceptions & special cases

  • Pressure‑relief valve capacities are determined by ASME BPVC VIII.1 (so valve manufacturers’ stamped capacities and ASME testing rules apply) — see § 1112.13.
  • For rupture members, P1 uses an adjusted pressure (the formula P1 = (psig × 1.1) + 14.7 psia) to account for transient pressure conditions — see § 1112.14.
  • For fusible plugs, P1 is tied to the plug’s stamped melting temperature or the refrigerant critical pressure (whichever is smaller) — see § 1112.14.
  • The CMC delegates the required relieving capacity calculation to ASHRAE 15; that means you must use ASHRAE 15 methods to compute the required C before applying the sizing formulas in § 1112.14 or selecting valves per § 1112.13. § 1113.5 states this adoption.

Common mistakes

  • Assuming the device-stamped capacity equals allowable installed capacity without accounting for backpressure or piping losses — the valve’s effective capacity may be reduced by piping; the CMC requires piping area at least equal to the valve inlet and uses ASME/ASHRAE methods to address reduced capacity (see § 1112.13 and the discharge‑piping rules referenced elsewhere in Chapter 11/1112).
  • Trying to size a rupture disk using valve sizing rules only — rupture members/fusible plugs have their own formula set in § 1112.14 and P1 rules that differ from valve rules.
  • Forgetting to determine the required C from ASHRAE 15 (adopted in § 1113.5) before solving for d or selecting devices.
  • Mixing units (lb/min vs kg/s) without using the code’s conversion factor (1 lb/min = 0.00756 kg/s) stated in § 1112.14.

Worked example — concrete scenario

Scenario: A pressure vessel requires a relief capacity of C_required = 100 lb/min (that required relieving capacity has been determined by ASHRAE 15 per § 1113.5). You are selecting a rupture member with a stamped rated set pressure of 200 psig.

Step 1 — compute P1 for a rupture member (per § 1112.14):
P1 = (rated pressure in psig × 1.1) + 14.7 psia
P1 = (200 × 1.1) + 14.7 = 220 + 14.7 = 234.7 psia.

Step 2 — use the rupture-member formula to solve for the minimum required smallest diameter d (Equation 1112.14(2)):
d = 1.25 × sqrt( C / P1 )

Plug in numbers:

  • sqrt(100 / 234.7) = sqrt(0.4263) = 0.6521
  • d = 1.25 × 0.6521 = 0.815 in

Interpretation & selection:

  • The code defines d as the smallest internal diameter of the inlet, retaining flange, plug or rupture member (inches). You must choose a rupture member and inlet flange/pipe with an internal opening ≥ 0.82 in (rounded). After selection, verify the selected rupture member’s stamped capacity and confirm that discharge piping and any backpressure will not reduce capacity below the required 100 lb/min (see § 1112.13 for valve piping area rule and the discharge piping/backpressure equations in adjacent discharge piping sections).

Notes:

  • If the device chosen has a reduced capacity rating because of piping/backpressure, you must increase the rupture member size or change piping so the effective capacity meets the ASHRAE-required C. § 1112.13 and related discharge‑piping rules cover these adjustments.

Related provisions (CMC sections)

  • § 1112.13 — Rating of Pressure‑Relief Device (ASME BPVC rating, piping area requirement).
  • § 1112.14 — Rating of Rupture Members and Fusible Plugs (formulas, P1 definitions, units).
  • § 1113.5 — Discharge Capacity (minimum required capacity determined in accordance with ASHRAE 15).
  • § 1112.12.2 — Discharge pipe size must be not less than the outlet size of the pressure‑relief device (useful when checking piping versus device inlet area).
  • § 1112.12.4 — Design backpressure and the discharge‑piping length/backpressure relationship (affects effective capacity).

Code references

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

  • CMC § 1112.14 High relevance — show source text

    Where:

    C = Rated discharge capacity expressed as mass flow of air, pounds per minute.

    d = Smallest of the internal diameter of the inlet pipe, retaining flanges, fusible plug, and rupture member , inches.

    For rupture members:

    [Equation 1112.14(3)]

    P1 = (rated pressure in psig x 1.1) + 14.7 psia

    For fusible plugs:

    P1 = Absolute saturation pressure corresponding to the stamped temperature melting point of the fusible plug or the critical pressure of the refrigerant used, whichever is smaller, pound-force per square inch atmosphere, psia. [ASHRAE 15:9.7.7]

    For SI units:1 pound per minute = 0.00756 kg/s

    1113.0 Overpressure Protection.

    1113.1 General. Pressure vessels shall be provided with overpressure protection in accordance with ASME BPVC Section VIII.1. Pressure vessels containing liquid refrigerant that are capable of being isolated by stop valves from other parts of a refrigerating system shall be provided with overpressure protection. Pressure relief devices or fusible plugs shall be sized in accordance with Section 1113.5. [ASHRAE 15:9.7.1, 9.7.2]

    »

    Unless the maximum allowable back pressure ( P0 ) is specified by the relief valve manufacturer, the following maximum allowable back pressure values shall be used for P0, where P is the set pressure and Pa is atmospheric pressure at the nominal elevation of the installation (see Table 1112.12.4):

    (1) For conventional relief valves: 15 percent of set

    pressure:

    P0 = (0.15• P )+ Pa [Equation 1112.12.4(2)] (2) For balanced relief valves: 25 percent of set pres sure:

    P0 = (0.25• P )+ Pa [Equation 1112.12.4(3)]

    (3) For rupture disks alone, fusible plugs, or pilot-operated relief devices: 50 percent of set pressure:

    P0 = (0.50• P )+ Pa [Equation 1112.12.4(4)]

    For fusible plugs, P shall be the saturated absolute pressure for the stamped temperature melting point of the fusible plug or the critical pressure of the refrigerant used, whichever is smaller. [ASHRAE 15:9.7.9.3.1, 9.7.9.3.2]

    TABLE 1112.12.4

    ATMOSPHERIC PRESSURE AT NOMINAL INSTALLATION ELEVATION ( Pa )

    [ASHRAE 15: TABLE 9-2]

  • CMC § 1112.12.4. High relevance — show source text

    ( P [2] 0 P 22 ) d - ln ( P0P2 )

    f - C [2] r 6 - f

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    REFRIGERATION

    expected to operate simultaneously, connect to a common discharge pipe, the common pipe shall be sized large enough to prevent the back pressure at each pressure-relief device from exceeding the maximum allowable back pressure in accordance with Section 1112.12.4.

    [ASHRAE 15:9.7.9.3.3]

    1112.13 Rating of Pressure-Relief Device. The rated discharge capacity of a pressure-relief device expressed in pounds of air per minute (kg/s), shall be determined in accordance with ASME BPVC Section VIII.1. Pipe and fittings between the pressure-relief valve and the parts of the system it protects shall have not less than the area of the pressurerelief valve inlet area. [ASHRAE 15:9.7.6]

    1112.14 Rating of Rupture Members and Fusible Plugs. The rated discharge capacity of a rupture member or fusible plug discharging to the atmosphere under critical flow conditions, in pounds of air per minute (kg/s), shall be determined in accordance with the following formulas:

    C = 0.64 P l d [2] [Equation 1112.14(1)]

    d = 1.25 √ C / P l [Equation 1112.14(2)]

    Where:

    C = Rated discharge capacity expressed as mass flow of air, pounds per minute.

    d = Smallest of the internal diameter of the inlet pipe, retaining flanges, fusible plug, and rupture member , inches.

    For rupture members:

    [Equation 1112.14(3)]

    P1 = (rated pressure in psig x 1.1) + 14.7 psia

    For fusible plugs:

    P1 = Absolute saturation pressure corresponding to the stamped temperature melting point of the fusible plug or the critical pressure of the refrigerant used, whichever is smaller, pound-force per square inch atmosphere, psia. [ASHRAE 15:9.7.7]

    For SI units:1 pound per minute = 0.00756 kg/s

    1113.0 Overpressure Protection.

    1113.1 General. Pressure vessels shall be provided with overpressure protection in accordance with ASME BPVC Section VIII.1. Pressure vessels containing liquid refrigerant that are capable of being isolated by stop valves from other parts of a refrigerating system shall be provided with overpressure protection. Pressure relief devices or fusible plugs shall be sized in accordance with Section 1113.5. [ASHRAE 15:9.7.1, 9.7.2]

    »

    Unless the maximum allowable back pressure ( P0 ) is specified by the relief valve manufacturer, the following maximum allowable back pressure values shall be used for P0, where P is the set pressure and Pa is atmospheric pressure at the nominal elevation of the installation (see Table 1112.12.4):

  • CMC § 9.9.4 High relevance — show source text

    [ASHRAE 15:9.9.4]

    240 2025 CALIFORNIA MECHANICAL CODE

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    REFRIGERATION

    1112.0 Pressure-Relief Devices.

    1112.1 General. Refrigeration systems shall be protected by a pressure-relief device or other approved means to safely relieve pressure due to fire or abnormal conditions. [ASHRAE 15:9.4.1] 1112.2 Positive Displacement Compressor. A positive displacement compressor with a stop valve in the discharge connection shall be equipped with a pressure-relief device that is sized, and with a pressure setting, in accordance with the compressor manufacturer to prevent rupture of the compressor or to prevent the pressure from increasing to more than 10 percent above the maximum allowable working pressure of any other component located in the discharge line between the compressor and the stop valve or in accordance with Section 1113.5, whichever is larger. The pressure-relief device shall discharge into the low-pressure side of the system or in accordance with Section 1112.11.

    Exception: Hermetic refrigerant motor-compressors that are listed and have a displacement not more than 50 cubic feet per minute (1.42 m [3] /min).

    The relief device(s) shall be sized based on compressor flow at the following conditions:

    (1) For compressors in single-stage systems and high-stage compressors of other systems, the flow shall be calculated based on 50°F (10°C) saturated suction temperature at the compressor suction.

    (2) For low-stage or booster compressors in compound refrigerating systems, the compressors that are capable of running only where discharging to the suction of a high-stage compressor, the flow shall be calculated based on the saturated suction temperature equal to the design operating intermediate temperature.

    (3) For low-stage compressors in cascade systems, the compressors that are located in the lower-temperature stage(s) of cascade systems, the flow shall be calculated based on the suction pressure being equal to the pressure setpoint of the pressure-relieving devices that protect the lowside of the stage against overpressure.

    Exceptions: For Section 1112.2(1), Section 1112.2(2), and Section 1112.2(3), the discharge capacity of the relief device shall be permitted to be the minimum regulated flow rate of the compressor where the following conditions are met:

    (1) The compressor is equipped with capacity regulation.

    (2) Capacity regulation actuates to a flow at not less than 90 percent of the pressure-relief device setting.

    (3) A pressure-limiting device is installed and set in accordance with the requirements of Section 1111.0.

    [ASHRAE 15:9.8] 1112.3 Liquid-Containing Portions of Systems. Liquid-containing portions of systems, including piping, that is isolated from pressure-relief devices required elsewhere, and that develops pressures exceeding their working design pressures due to temperature rise, shall be protected by the installation of pressure-relief devices. 1112.4 Evaporators. Heat exchanger coils located downstream, or upstream within 18 inches (457 mm), of a heating source and capable of being isolated shall be fitted with a

  • CMC § 1112.11.3 High relevance — show source text

    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]

    1112.11.4.1 Water (R-718). Where water is the only refrigerant, discharge to a floor drain shall be permitted where all of the following conditions are

    met:

    (1) The pressure-relief device set pressure shall not exceed 15 psig (103 kPag).

    (2) The floor drain shall be sized to handle the flow rate from a single broken tube in any refrigerantcontaining heat exchanger.

    (3) Either of the following:

    (a) The Authority Having Jurisdiction finds it acceptable that the working fluid, corrosion inhibitor, and other additives used in this type of refrigeration system are permitted to infrequently be discharged to the sewer system, or

    (b) A catch tank sized to handle the expected discharge shall be installed and equipped

    For SI units: 1 foot = 304.8 mm, 1 pound-force per square inch =

    6.8947 kPa, 1 pound per minute = 0.00756 kg/s

    with a normally closed drain valve and an overflow line to drain. [ASHRAE 15:9.7.8.4.1]

    1112.12 Discharge Piping. The piping used for pressure-relief device discharge shall be in accordance with Section 1112.12.1 through Section 1112.12.5. [ASHRAE 15:9.7.9]

    1112.12.1 Piping Connection. Piping connected to the discharge side of a fusible plug or rupture member shall have provisions to prevent plugging of the pipe upon operation of a fusible plug or rupture member.

    [ASHRAE 15:9.7.9.1]

    1112.12.2 Pipe Size. The size of the discharge pipe from the pressure-relief device or fusible plug shall be not less than the outlet size of the pressure-relief device or fusible plug. [ASHRAE 15:9.7.9.2]

  • CMC § 1112.12.4 High relevance — show source text

    1112.12.4 Design Back Pressure. The design back pressure due to flow in the discharge piping at the outlet of pressure relief devices and fusible plugs, discharging to atmosphere, shall be limited by the allowable equivalent length of piping determined in accordance with Equation 1112.12.4(1).

    [Equation 1112.12.4(1)]

    L= 0.2146 - d [5] ( P [2] 0 P 22 ) d - ln ( P0P2 )

    f - C [2] r 6 - f

    Where:

    L = Equivalent length of discharge piping, feet.

    Cr = Rated capacity as stamped on the pressure relief device in pounds per minute (lb/min), or in standard cubic feet per minute (SCFM) multiplied by 0.0764, or as calculated in Section 1112.14 for a rupture member or fusible plug, or as adjusted for reduced capacity due to piping in accordance with the manufacturer of the device, or as adjusted for reduced capacity due to piping as estimated by an approved method.

    f = Moody friction factor in fully turbulent flow.

    d = Inside diameter of pipe or tube, inches.

    ln = Natural logarithm.

    P2 = Absolute pressure at outlet of discharge piping, psia.

    P0 = Allowed back pressure (absolute) at the outlet of pressure relief device, psia.

    22 ) d - ln (

    L=

    0.2146 - d [5] ( P [2] 0 P

    ( P [2] 0 P 22 ) d - ln ( P0P2 )

    f - C [2] r 6 - f

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    REFRIGERATION

    expected to operate simultaneously, connect to a common discharge pipe, the common pipe shall be sized large enough to prevent the back pressure at each pressure-relief device from exceeding the maximum allowable back pressure in accordance with Section 1112.12.4.

    [ASHRAE 15:9.7.9.3.3]

    1112.13 Rating of Pressure-Relief Device. The rated discharge capacity of a pressure-relief device expressed in pounds of air per minute (kg/s), shall be determined in accordance with ASME BPVC Section VIII.1. Pipe and fittings between the pressure-relief valve and the parts of the system it protects shall have not less than the area of the pressurerelief valve inlet area. [ASHRAE 15:9.7.6]

    1112.14 Rating of Rupture Members and Fusible Plugs. The rated discharge capacity of a rupture member or fusible plug discharging to the atmosphere under critical flow conditions, in pounds of air per minute (kg/s), shall be determined in accordance with the following formulas:

    C = 0.64 P l d [2] [Equation 1112.14(1)]

  • CMC § 9.9 Medium relevance — show source text

    Exception: Pressure limiting devices are not required for listed factory-sealed systems containing less than 22 pounds (9.9 kg) of Group A1 refrigerant. [ASHRAE 15:9.9.1] 1111.2 Setting. Pressure limiting devices shall be set in accordance with one the following:

    (1) For positive displacement compressors:

    (a) When systems are protected by a highside pressure relief device, the compressor’s pressure limiting device shall be set not more than 90 percent of the operating pressure for the highside pressure relief device.

    (b) When systems are not protected by a highside pressure relief device, the compressor’s pressure limiting device shall be set not more than the system’s highside design pressure.

    (2) For nonpositive displacement compressors:

    (a) When systems are protected by a highside pressure relief device, the compressor’s pressure limiting device shall be set not more than 90 percent of the operating pressure for the highside pressure relief device.

    (b) When systems are protected by a lowside pressure relief device that is only subject to lowside pressure, and is provided with a permanent relief path between the systems’ highside and lowside, without intervening valves, the compressor’s pressure limiting device shall be set not more than the systems’ highside design pressure. [ASHRAE 15:9.9.2]

    1111.3 Location. Stop valves shall not be installed between the pressure imposing element and pressure limiting devices serving compressors. [ASHRAE 15:9.9.3] 1111.4 Emergency Stop. Activation of a pressure-limiting device shall stop the action of the pressure-imposing element.

    [ASHRAE 15:9.9.4]

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    REFRIGERATION

    1112.0 Pressure-Relief Devices.

    1112.1 General. Refrigeration systems shall be protected by a pressure-relief device or other approved means to safely relieve pressure due to fire or abnormal conditions. [ASHRAE 15:9.4.1] 1112.2 Positive Displacement Compressor. A positive displacement compressor with a stop valve in the discharge connection shall be equipped with a pressure-relief device that is sized, and with a pressure setting, in accordance with the compressor manufacturer to prevent rupture of the compressor or to prevent the pressure from increasing to more than 10 percent above the maximum allowable working pressure of any other component located in the discharge line between the compressor and the stop valve or in accordance with Section 1113.5, whichever is larger. The pressure-relief device shall discharge into the low-pressure side of the system or in accordance with Section 1112.11.

    Exception: Hermetic refrigerant motor-compressors that are listed and have a displacement not more than 50 cubic feet per minute (1.42 m [3] /min).

    The relief device(s) shall be sized based on compressor flow at the following conditions:

    (1) For compressors in single-stage systems and high-stage compressors of other systems, the flow shall be calculated based on 50°F (10°C) saturated suction temperature at the compressor suction.

  • CMC § 110.2 Medium relevance — show source text

    Compliance with the cooling-only perfor-
    mance is required as defined in Notes b and c of Table 110.2-I.
    h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
    i. Source leaving liquid temperature.
    1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full-load cool-
    ing rating.
    2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
    from the cooling operation full-load rating.
    3. For heating-only fluid-to-fluid chiller packages, the evaporator flow rate obtained with an entering liquid temperature of 54°F and a leaving liquid temperature of 44°F
    shall be used.
    j. NA means the requirements are not applicable.|a. The size category is the full-load net refrigeration cooling mode capacity, which is the capacity of the evaporator available for cooling of the thermal load external to the chill-
    ing package.
    b. For air source heat pumps, compliance with both the 47°F and 17°F heating source outdoor air temperature (OAT) rating efficiency is required for heating.
    c. Heating full-load rating conditions are at standard rating conditions defined in AHRI 550/590 (I-P), Table 4, which includes the impact of defrost for air source heating ratings.
    d. For units that operate in both cooling and heating, compliance with both the cooling and heating efficiency is required.
    e. For heat recovery heating chilling package applications where there is simultaneous cooling and heating, compliance with the heating performance heat recover COPHR is
    only required at one of the four heating AHRI 550/590 (I-P) standard ratings conditions of Low, Medium, Hot-Water 1 or Hot-Water 2. Compliance with the cooling-only perfor-
    mance is required as defined in Notes b and c of Table 110.2-I.
    f. For liquid source heat recovery chilling packages that have capabilities for heat rejection to a heat recovery condenser and a tower condenser, the COPHR applies to operation
    at full load with 100 percent heat recovery (no tower rejection). Units that only have capabilities for partial heat recovery shall meet the requirements of Table 110.2-D, Water
    Chilling Packages—Minimum Efficiency Requirements.
    g. For heat recovery heating chilling package applications where there is simultaneous cooling and heating, compliance with the heating performance heat recover COPHR is
    only required at one of the four heating AHRI 550/590 (I-P) standard ratings conditions of Low, Medium, Hot-Water 1 or Hot-Water 2. Compliance with the cooling-only perfor-
    mance is required as defined in Notes b and c of Table 110.2-I.
    h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
    i. Source leaving liquid temperature.
    1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full-load cool-
    ing rating.
    2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
    from the cooling operation full-load rating.
    3.

  • CMC § 304.8 Medium relevance — show source text

    (2) The floor drain shall be sized to handle the flow rate from a single broken tube in any refrigerantcontaining heat exchanger.

    (3) Either of the following:

    (a) The Authority Having Jurisdiction finds it acceptable that the working fluid, corrosion inhibitor, and other additives used in this type of refrigeration system are permitted to infrequently be discharged to the sewer system, or

    (b) A catch tank sized to handle the expected discharge shall be installed and equipped

    For SI units: 1 foot = 304.8 mm, 1 pound-force per square inch =

    6.8947 kPa, 1 pound per minute = 0.00756 kg/s

    with a normally closed drain valve and an overflow line to drain. [ASHRAE 15:9.7.8.4.1]

    1112.12 Discharge Piping. The piping used for pressure-relief device discharge shall be in accordance with Section 1112.12.1 through Section 1112.12.5. [ASHRAE 15:9.7.9]

    1112.12.1 Piping Connection. Piping connected to the discharge side of a fusible plug or rupture member shall have provisions to prevent plugging of the pipe upon operation of a fusible plug or rupture member.

    [ASHRAE 15:9.7.9.1]

    1112.12.2 Pipe Size. The size of the discharge pipe from the pressure-relief device or fusible plug shall be not less than the outlet size of the pressure-relief device or fusible plug. [ASHRAE 15:9.7.9.2]

    1112.12.3 Maximum Length. The maximum length of the discharge piping installed on the outlet of pressure-relief devices and fusible plugs discharging to the atmosphere shall be determined in accordance with Section 1112.12.4 and Section 1112.12.5. {ASHRAE 15:9.7.9.3}

    1112.12.4 Design Back Pressure. The design back pressure due to flow in the discharge piping at the outlet of pressure relief devices and fusible plugs, discharging to atmosphere, shall be limited by the allowable equivalent length of piping determined in accordance with Equation 1112.12.4(1).

    [Equation 1112.12.4(1)]

    L= 0.2146 - d [5] ( P [2] 0 P 22 ) d - ln ( P0P2 )

    f - C [2] r 6 - f

    Where:

    L = Equivalent length of discharge piping, feet.

    Cr = Rated capacity as stamped on the pressure relief device in pounds per minute (lb/min), or in standard cubic feet per minute (SCFM) multiplied by 0.0764, or as calculated in Section 1112.14 for a rupture member or fusible plug, or as adjusted for reduced capacity due to piping in accordance with the manufacturer of the device, or as adjusted for reduced capacity due to piping as estimated by an approved method.

    f = Moody friction factor in fully turbulent flow.

    d = Inside diameter of pipe or tube, inches.

    ln = Natural logarithm.

    P2 = Absolute pressure at outlet of discharge piping, psia.

  • CMC § 304.8 Medium relevance — show source text

    For SI units: 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa

    1112.12.5 Simultaneous Operation. When outlets of two or more relief devices or fusible plugs, which are

    TABLE 1112.12.4

    ATMOSPHERIC PRESSURE AT NOMINAL INSTALLATION ELEVATION ( Pa )

    [ASHRAE 15: TABLE 9-2]

    For SI units: 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa

    244 2025 CALIFORNIA MECHANICAL CODE

    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    REFRIGERATION

    1113.2 Type of Protection. Pressure vessels with an internal gross volume of 3 cubic feet (0.1 m [3] ) or less shall use one or more pressure relief devices or a fusible plug. Pressure vessels of more than 3 cubic feet (0.1 m [3] ) but less than 10 cubic feet (0.28 m [3] ) internal gross volume shall use one or more pressure relief devices. Fusible plugs shall not be used.

    [ASHRAE 15:9.7.2.1, 9.7.2.2]

    1113.3 Discharging into Lowside of System. For pressure-relief valves discharging into the lowside of the system, a single relief valve (not rupture member) of the required relieving capacity shall not be used on vessels of 10 cubic feet (0.28 m [3] ) or more internal gross volume except under the conditions permitted in Section 1112.11.3. [ASHRAE 15:9.7.3]

    1113.4 Parallel Pressure-Relief Devices. Two or more

    pressure-relief devices in parallel to obtain the required capacity shall be considered as one pressure-relief device. The discharge capacity shall be the sum of the capacities required for each pressure vessel being protected.

    1113.5 Discharge Capacity. The minimum required discharge capacity of the pressure-relief device or fusible plug for a pressure vessel shall be determined in accordance with ASHRAE 15.

    1113.6 Three-Way Valve. Pressure vessels of 10 cubic feet (0.28 m [3] ) or more internal gross volume shall use one or more rupture member(s) or dual pressure-relief valves where discharging to the atmosphere. Dual pressure-relief valves shall be installed with a three-way valve to allow testing or repair. Where dual relief valves are used, the valve shall comply with Section 1113.5.

    Exception: A single relief valve shall be permitted on pressure vessels of 10 cubic feet (0.28 m [3] ) or more internal gross volume where in accordance with the following conditions:

    (1) The relief valves are located on the lowside of the sys tem.

    (2) The vessel is provided with shutoff valves designed to allow pumpdown of the refrigerant charge of the pressure vessel.

    (3) Other pressure vessels in the system are separately protected in accordance with Section 1113.1. [ASHRAE 15:9.7.2.3]

    1114.0 Special Discharge Requirements.

  • CMC § 5503.2.2 Medium relevance — show source text

    5503.2.2 Vessels or equipment other than containers. Heat exchangers, vaporizers, insulation casings surrounding containers, vessels and coaxial piping systems in which liquefied cryogenic fluids could be trapped because of leakage from the primary container shall be provided with a pressure relief device.

    5503.2.3 Sizing. Pressure relief devices shall be sized in accordance with the specifications to which the container was fabricated. The relief device shall have sufficient capacity to prevent the maximum design pressure of the container or system from being exceeded.

    5503.2.4 Access. Pressure relief devices shall be located such that they are provided with ready access for inspection and repair.

    5503.2.5 Arrangement. Pressure relief devices shall be arranged to discharge unobstructed to the open air in such a manner as to prevent impingement of escaping gas on personnel, containers, equipment and adjacent structures or to enter enclosed spaces. Exception: DOTn-specified containers with an internal volume of 2 cubic feet (0.057 m [3] ) or less.

    5503.2.6 Shutoffs between pressure relief devices and containers. Shutoff valves shall not be installed between pressure relief devices and containers.

    Exceptions:

    1. A shutoff valve is allowed on containers equipped with multiple pressure relief device installations where the arrangement of the valves provides the full required flow through the minimum number of required relief devices at all times.
    2. A locking-type shutoff valve is allowed to be used upstream of the pressure relief device for service-related work performed by the supplier when in accordance with the requirements of the ASME Boiler and Pressure Vessel Code .

    5503.2.7 Temperature limits. Pressure relief devices shall not be subjected to cryogenic fluid temperatures except when operating.

    5503.3 Pressure relief vent piping. Pressure relief vent-piping systems shall be constructed and arranged so as to remain functional and direct the flow of gas to a safe location in accordance with Sections 5503.3.1 and 5503.3.2.

    5503.3.1 Sizing. Pressure relief device vent piping shall have a cross-sectional area not less than that of the pressure relief device vent opening and shall be arranged so as not to restrict the flow of escaping gas.

    5503.3.2 Arrangement. Pressure relief device vent piping and drains in vent lines shall be arranged so that escaping gas will discharge unobstructed to the open air and not impinge on personnel, containers, equipment and adjacent structures or enter enclosed spaces. Pressure relief device vent lines shall be installed in such a manner to exclude or remove moisture and condensation and prevent malfunction of the pressure relief device because of freezing or ice accumulation.

    5503.4 Marking. Cryogenic containers and systems shall be marked in accordance with Sections 5503.4.1 through 5503.4.6.

    5503.4.1 Identification signs. Visible hazard identification signs in accordance with NFPA 704 shall be provided at entrances to buildings or areas in which cryogenic fluids are stored, handled or used.

    5503.4.2 Identification of contents. Stationary and portable containers shall be marked with the name of the gas contained. Stationary above-ground containers shall be placarded in accordance with Sections 5003.5 and 5003.6. Portable containers shall be identified in accordance with CGA C-7.

  • CMC § 1112.13 Medium relevance — show source text

    1112.13 Rating of Pressure-Relief Device. . . . . . . . . . . . . . . . . . . . . . 244

    1112.14 Rating of Rupture Members and Fusible Plugs . . . . . . . . . . . . . . . . 244

    1113.0 Overpressure Protection. . . . . . . . 244

    1113.1 General. . . . . . . . . . . . . . . . . . . . . 244

    1113.2 Type of Protection . . . . . . . . . . . . 245

    1113.3 Discharging into Lowside of System . . . . . . . . . . . . . . . . . . . . . 245

    1113.4 Parallel Pressure-Relief Devices . . 245

    1113.5 Discharge Capacity . . . . . . . . . . . 245

    1113.6 Three-Way Valve . . . . . . . . . . . . . 245

    1114.0 Special Discharge Requirements. . 245

    1114.1 General. . . . . . . . . . . . . . . . . . . . . 245

    1114.2 Design Requirements . . . . . . . . . . 245

    1114.3 Testing . . . . . . . . . . . . . . . . . . . . . 245

    1115.0 Labeling and Identification . . . . . . 245

    1115.1 General. . . . . . . . . . . . . . . . . . . . . 245

    1115.2 Volume and Type . . . . . . . . . . . . . 245

    1115.3 Permanent Sign . . . . . . . . . . . . . . 245

    1115.4 Marking of Pressure-Relief Devices. . . . . . . . . . . . . . . . . . . . . 245

    1115.5 Nameplate . . . . . . . . . . . . . . . . . . 245

    1116.0 Testing of Refrigeration Equipment . . . . . . . . . . . . . . . . . . 246

    1116.1 Factory Tests . . . . . . . . . . . . . . . . 246

    1116.2 Field Tests . . . . . . . . . . . . . . . . . . 246

    1116.3 Test Gases . . . . . . . . . . . . . . . . . . 246

    1116.4 Declaration . . . . . . . . . . . . . . . . . . 246

    1116.5 Brine Systems . . . . . . . . . . . . . . . 247

    1117.0 Refrigerant-Containing Pressure Vessels . . . . . . . . . . . . . . . . . . . . . 247

    1117.1 Inside Dimensions 6 Inches

    or Less . . . . . . . . . . . . . . . . . . . . . 247

    1117.2 Inside Dimensions More than

    6 Inches . . . . . . . . . . . . . . . . . . . . 247

    1117.3 Pressure Vessels for 15 psig or Less . . . . . . . . . . . . . . . . . . . . . 247

  • CMC § 1112.1 Medium relevance — show source text

    1112.1 General. . . . . . . . . . . . . . . . . . . . . 241

    1112.2 Positive Displacement Compressor . . . . . . . . . . . . . . . . . 241

    1112.3 Liquid-Containing Portions of Systems . . . . . . . . . . . . . . . . . . 241

    1112.4 Evaporators . . . . . . . . . . . . . . . . . 241

    1112.5 Hydrostatic Expansion . . . . . . . . . 241

    1112.6 Actuation. . . . . . . . . . . . . . . . . . . . 242

    1112.7 Stop Valves Prohibited . . . . . . . . . 242

    1112.8 Location . . . . . . . . . . . . . . . . . . . . 242

    1112.9 Materials . . . . . . . . . . . . . . . . . . . . 242

    1112.10 Pressure-Relief Valve Setting . . . . 242

    1112.11 Discharge from Pressure-Relief Devices. . . . . . . . . . . . . . . . . . . . . 242

    1112.12 Discharge Piping . . . . . . . . . . . . . 243

    Table 1112.12.4 Atmospheric Pressure at Nominal

    Installation Elevation. . . . . . . . . . . 244

    xxxix

    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    TABLE OF CONTENTS

    1112.13 Rating of Pressure-Relief Device. . . . . . . . . . . . . . . . . . . . . . 244

    1112.14 Rating of Rupture Members and Fusible Plugs . . . . . . . . . . . . . . . . 244

    1113.0 Overpressure Protection. . . . . . . . 244

    1113.1 General. . . . . . . . . . . . . . . . . . . . . 244

    1113.2 Type of Protection . . . . . . . . . . . . 245

    1113.3 Discharging into Lowside of System . . . . . . . . . . . . . . . . . . . . . 245

    1113.4 Parallel Pressure-Relief Devices . . 245

    1113.5 Discharge Capacity . . . . . . . . . . . 245

    1113.6 Three-Way Valve . . . . . . . . . . . . . 245

    1114.0 Special Discharge Requirements. . 245

    1114.1 General. . . . . . . . . . . . . . . . . . . . . 245

    1114.2 Design Requirements . . . . . . . . . . 245

    1114.3 Testing . . . . . . . . . . . . . . . . . . . . . 245

    1115.0 Labeling and Identification . . . . . . 245

    1115.1 General. . . . . . . . . . . . . . . . . . . . . 245

    1115.2 Volume and Type . . . . . . . . . . . . . 245

  • CMC § 6-9 Medium relevance — show source text

    Positio
    W|PG&E Service Condu
    (in the Center Positio
    W|

    Figure 6-9 Overhead- or Underground-Fed Combination Meter and Service-Termination Panel (225 Amps, 1 � )

    Table 6-2 Residential Combination (OH/UG) Meter Panel

    Rating in Amps X Y N W Conduit
    Range
    Rating in Amps Minimum Dimensions (In Inches) Minimum Dimensions (In Inches) Minimum Dimensions (In Inches) Minimum Dimensions (In Inches) Minimum Dimensions (In Inches)
    225 12 7 9½ 6½ 3 – 4

    6-13 2022 – 2023

    Section 6, Electric Metering: Residential

    6.4.3. (continued)

    Meter Socket (Notes 2 & 4) Manual Bypass Studs (Note 3)

    1-1/8” Min.

    Col1 Col2
    1
    		 1

    Hex Screw Lug

    Col1 Col2 Col3 Col4
    3/

    1-
    1/2”
    in.    		 1/2”
    in.    		 1/2”
    in.    		 1/2”
    in.

    Front View

    See Note 3

    Neutral Bonded To Enclosure

    Sealing Provisions

    3/4”

    1-1/2”

    1” Min.

    Side View

    Figure 6-10 Overhead or Underground Service-Termination Meter Panel with Manual Bypass studs (320 Amps, 120/240-Volt, 1 � )

    Notes in Reference to Figure 6-10.

    1. Ensure that this service equipment is marked with a continuous amp rating of 320 amps. Alternatively, service equipment can be marked “400 amp” (320 amps continuous).

    2. Each phase bus section must include 12−24 bypass studs, 1/2 inches in height with 1/2−inch hex nuts (measured across the flat). The studs must have a horizontal spacing of 1-1/2 inch (measured from the centers) between the line- and load-bus sections and must be offset from the line-side termination lugs to permit cable to enter from the top without interfering with the utility-provided manual bypass links.

    3. Terminations for service conductors must be aluminum-bodied mechanical lugs with a range-taking ability of #1 American Wire Gauge (AWG) through 600 thousand circular mils (kcmil). The lugs must be secured to ensure vertical alignment. Line-side lugs must be offset from the face of the bus to permit cable to enter from the top. The line and load positions must be identified in 3/4-inch high block letters.

    2022 – 2023 6-14

    Section 6, Electric Metering: Residential

    6.4.4. Multiple Meters

    PG&E requires grouped, single-meter installations for multifamily residential buildings.

    This requirement excludes row-type condominiums where each unit is considered a single-family residence and is metered individually. Row-type condominiums must meet the applicable metering requirements described in the following subsections.

  • CMC § 2.25 Medium relevance — show source text

    000 Btu/h and
    < 135,000 Btu/h
    (cooling capacity)|17°F db/15°F wb
    outdoor air|2.25 COP|2.25 COP| |Air cooled
    (heating mode)
    Split system and single package|≥ 135,000 Btu/h and
    < 240,000 Btu/h
    (cooling capacity)|47°F db/43°F wb
    outdoor air|Federal Minimum COP|Federal Minimum COP| |Air cooled
    (heating mode)
    Split system and single package|≥ 240,000 Btu/h and
    < 760,000 Btu/h|≥ 240,000 Btu/h and
    < 760,000 Btu/h|Federal Minimum COP|Federal Minimum COP| |Air cooled
    (heating mode)
    Split system and single package|≥ 135,000 Btu/h
    (cooling capacity)|17°F db/15°F wb
    outdoor air|2.05 COP|2.05 COP| |Water source
    (heating mode)|< 135,000 Btu/h
    (cooling capacity)|68ºF entering water|Federal Minimum COP|ISO-13256-1| |Water source
    (heating mode)|≥ 135,000 Btu/h and
    < 240,000 Btu/h|68ºF entering water|Federal Minimum COP|ISO-13256-1| |Groundwater source
    (heating mode)|< 135,000 Btu/h
    (cooling capacity)|50ºF entering water|3.7 COP|ISO-13256-1| |Ground source
    (heating mode)|< 135,000 Btu/h
    (cooling capacity)|32ºF entering water|3.2 COP|ISO-13256-1| |Water source water-to-water
    (heating mode)|< 135,000 Btu/h
    (cooling capacity)|68ºF entering water|3.7 COP|ISO-13256-2| |Groundwater source water-to-
    water
    (heating mode)|< 135,000 Btu/h
    (cooling capacity)|50ºF entering water|3.1 COP|ISO-13256-2| |Ground source brine-to-water
    (heating mode)|< 135,000 Btu/h
    (cooling capacity)|32ºF entering water|2.5 COP|ISO-13256-2| |a. Deduct 0.2 from the required EERs and IEERs for units with a heating section other than electric resistance heat.
    b. Applicable test procedure and reference year are provided under the definitions.|a. Deduct 0.2 from the required EERs and IEERs for units with a heating section other than electric resistance heat.
    b. Applicable test procedure and reference year are provided under the definitions.|a. Deduct 0.2 from the required EERs and IEERs for units with a heating section other than electric resistance heat.
    b. Applicable test procedure and reference year are provided under the definitions.|a. Deduct 0.2 from the required EERs and IEERs for units with a heating section other than electric resistance heat.
    b. Applicable test procedure and reference year are provided under the definitions.|a. Deduct 0.2 from the required EERs and IEERs for units with a heating section other than electric resistance heat.
    b. Applicable test procedure and reference year are provided under the definitions.|

  • CMC § 0.25 Medium relevance — show source text

    g|NA|0.25g|(0.25)g|NA|0.25g|(0.25)g| |Oxidizer|3j|H-2 or H-3|10d, e|(10)d, e|(10)d, e|2d|(2)d|(2)d|2d|(2)d| |Oxidizer|2|H-3|250d, e|(250)d, e|(250)d, e|250d|(250)d|(250)d|50d|(50)d| |Oxidizer|1|NA|4,000e, f|(4,000)e, f|(4,000)e, f|4,000f|(4,000)f|(4,000)f|1,000f|(1,000)f| |Oxidizing gas|Gaseous|H-3|NA|NA|1,500d,e|NA|NA|1,500d, e|NA|NA| |Oxidizing gas|Liquefied|Liquefied|Liquefied|(150)d, e|NA|NA|(150)d, e|NA|NA|NA| |Pyrophoric|NA|H-2|4e, g|(4)e, g|50e, g|1g|(1)g|10e, g|0|0| |Unstable
    (reactive)|4|H-1|1e, g|(1)e, g|10e, g|0.25g|(0.25)g|2e, g|0.25g|(0.25)g| |Unstable
    (reactive)|3|H-1 or H-2|5d, e|(5)d, e|50d, e|1d|(1)d|10d, e|1d|(1)d| |Unstable
    (reactive)|2|H-3|50d, e|(50)d, e|750d, e|50d|(50)d|750d, e|10d|(10)d| |Unstable
    (reactive)|1|NA|NL|NL|NL|NL|NL|NL|NL|NL| |Water
    reactive|3|H-2|5d, e|(5)d, e|NA|5d|(5)d|NA|1d|(1)d| |Water
    reactive|2|H-3|50d, e|(50)d, e|(50)d, e|50d|(50)d|(50)d|10d|(10)d| |Water
    reactive|1|NA|NL|NL|NL|NL|NL|NL|NL|NL| |For SI: 1 cubic foot = 0.02832 m3, 1 pound = 0.454 kg, 1 gallon = 3.785 L.
    NA = Not Applicable, NL = Not Limited, UD = Unclassified Detonable.
    a. For use of control areas, see Section 5003.8.3.
    b. The aggregate quantity in use and storage shall not exceed the maximum allowance quantity for storage, including applicable increases.
    c. For hazardous materials in Group B higher education laboratory occupancies, see Section 428 of the_California Building Code_ and Chapter 38.
    d._ [SFM]__ In other than Group L occupancies, maximum allowable quantities shall be increased 100 percent in buildings equipped throughout with an automatic sprinkler system in_
    _accordance with Section 903.3.1.1.

  • CEC § 2022 Medium relevance — show source text

    1. All disconnect devices must have locking provisions that accept a PG&E padlock with a 5/16-inch lock shaft. Keyed locks are not allowed. If the disconnect device is operable without opening the enclosure, the operating handle must be lockable. If the enclosure must be opened to operate the disconnect device, the enclosure must be lockable.

    2. Molded case circuit breakers, pull-out type disconnects, or any other similar device are not acceptable as an approved disconnect switch.

    3. For applications not described, contact the PG&E Electric Generation Interconnection (EGI) department.

    4. Interconnections in any PG&E sealable compartment are NOT allowed without written authorization from the Electric Meter Engineering or Electric Distribution Standards departments. For any questions, contact PG&E’s EGI department.

    Rev. #07: 3/25/2022 060559 Page 1 of 7

    Greenbook

    Disconnect Switch Requirements for Distributed Generation Customers

    Disconnect Switch Requirements

    Basic

    As specified and in Electric Rule 21, “Generating Facility Interconnections,” and in PG&E’s Distribution Interconnection Handbook, the generating system or facility must have an ac disconnect switch. The device must meet all of the PG&E requirements, as specified in this document.

    All disconnect switches must conform to nationally recognized standards and meet all applicable certification requirements. These include, but are not limited to: NFPA 70−National Electrical Code (NEC), California Electrical Code (CEC), Underwriters Laboratories (UL), or other Nationally Recognized Testing Laboratory (NRTL).

    PG&E-approved disconnect switch models, rated up to 1200 amps, currently listed in both the Eaton and Siemens Safety Switch Cross-Reference Guides, meet all of the functional requirements described below. These guides can be found on PG&E’s Distribution Interconnection Handbook website at http://www.pge.com/dih/. Disconnect switches rated over 1200 amps and up to 4000 amps must meet all of the requirements described in this document.

    Functional

    • Manually operated: Operated by a person and not operated electronically.

    • Gang-operated: One switch handle opens and closes all phases simultaneously.

    • Includes marking or signage on the switch that clearly indicates the open (off) and closed (on) positions.

    • Lockable in the open (off) position using a PG&E padlock.

    • Allows visible verification that an air-gap of separation has occurred between the blades and contact points.

    • Has a viewing window, for visible verification, on all pad−mounted (floor standing) disconnect switches. A viewing window is not required, but allowed, on all wall−mounted disconnect switches.

    • A fusible ac disconnect switch is required for generators that do not have over-current protection (i.e., breakers, fuses) at the point of interconnection with the utility.

    • Adequately sized to handle fault and overcurrent conditions.

    Labeling

    • Permanently attached signage on the front that explains this is the ac disconnect switch for the generation. Example: “UTILITY AC DISCONNECT SWITCH”.

    • Labels shall be permanent and suitable for the environment and shall be engraved phenolic or comply with ANSI Z535.4. Lettering shall be a minimum 3/8” high and in all capitals.

    • When the disconnect switch is not grouped with the meter panel provide a map showing the location.

  • CMC § 03-25 Medium relevance — show source text

    |1/0 Str.| |Run|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.|2/0 Str.| |Run|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.|3/0 Str.| |Run|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.|4/0 Str.| |Run|250|250|250|250|250|250|250|250|250|250|−|−|

    Table 17 Die Information for YP-C (Figure-6 Type) Connectors ( Figure 13)

    Manufacture and
    Catalog Numbers    		 Col2 Die 1, 2 Connector
    Code    		 Required
    Number of
    Compressions
    Brundy Dossert Die Die Die
    YP2C2 DC6 U-O 305844 1
    YP29C26 DC25−13 U-D3 305845 1
    YP28C28 − U-D3 012086 1

    1 These dies use a 12-ton press tool. 2 Refer to Table 24 on Page 21 for Die ordering information.

    015251 Page 18 of 39 Rev. #07: 03-25-22

    UG-1: Connectors Greenbook Connectors for Insulated Cables Underground Distribution Systems

    Tap Connectors Compression Type for Secondary Conductors (copper-to-copper (continued)

    Table 18 Blackburn, Homac, Kearney and Penn-Union H-Tap

    Figure 14 Blackburn, Kearney, Homac, Penn-Union H-Tap Type

    Copper Col2 Connectors (Figure 14) Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 Col12 Col13
    Conductor Size
    AWG or kcmil    		 Conductor Size
    AWG or kcmil    		 Tap Tap Tap Tap Tap Tap Tap Tap Tap Tap Tap
    Conductor Size
    AWG or kcmil    		 Conductor Size
    AWG or kcmil    		 #6 Sol. #4 Sol. #4 Str. #2 Sol. #1 Sol. #2 Str. 1/0 Sol. 1/0 Str. 2/0 Str. 3/0 Str. 4/0 Str.
    Run #6 Sol.
  • CMC § 1.75 Medium relevance — show source text

    250|1.75|0.65|3.25|9.25|6.00|303844|303844| |1/0|2|SAPT-1/0-26|YE25R-60|0.250|1.75|0.65|3.25|9.25|6.00|303845|303845| |4/0|2/0|SAPT-4/0-206|YE28R-60|0.375|1.54|0.91|3.50|10.9|6.00|303846|W249
    U249
    U2492| |350|4/0|PTB-350-6|YE31AG3|0.460|2.25|1.12|4.70|10.7|6.00|303554|−
    U31ART
    U31ART2| |500/60
    0|500|PTM-500-346|YE34AP-
    GE|0.750|2.56|1.57|6.30|12.3|6.00|300013|−
    U34ART3
    U34ART2,3| |700|500|PTL-750|YE39AGB|0.750|2.56|1.60|6.30|12.3|6.00|303555|−
    −
    P39ART| |1,000|700|PTF-1000-34
    6|YE44AG7|0.750|2.56|1.60|6.30|12.3|6.00|033757|−
    −
    P44ART|

    1 Within this column, the first entry corresponds to a 6-ton press tool, the second entry corresponds to a 12-ton press tool, and the third entry corresponds to a 15-ton press tool. 2 A U-die adapter must be used when utilizing U-dies in 15-ton press tool. 3 Homac equivalent of this die is 106A.

    Notes

    1. The material for the pin terminals is on Table 41. Copper Rod-Soft Drawn, Tinned, Aluminum Connector EC Grade, Untinned

    2. Connector is supplied pre-filled with inhibitor and sealed.

    3. Connector is supplied pre-filled with inhibitor and sealed.

    4. Pin terminals connected to copper secondary conductors use a copper connector. Pin terminals connected to aluminum secondary conductors use a fired wedge or h-tap.

    Application

    1. To make straight connections of insulated aluminum secondary neutral to bare copper neutral, see Note 10 Page 7.
    2. To connect aluminum primary stress cone termination to terminal tap connector or cutout.
    3. To make watertight termination for secondary risers.

    015251 Page 38 of 39 Rev. #07: 03-25-22

    UG-1: Connectors Greenbook Connectors for Insulated Cables Underground Distribution Systems

    Pin Terminals (continued)

    Table 42 Color Coding Col2
    Color Coding Requirements for Plastic End Plugs in Pin Terminals Color Coding Requirements for Plastic End Plugs in Pin Terminals
    Conductor Size Plug Color
    #6 Blue
    #2 Red
    1/0 Yellow
    4/0 Pink
    350 Brown
    700 Purple

    Table 43 Specifications and Ordering Information for Copper Pin Terminal

  • CMC § 7-11 Medium relevance — show source text

    000|7-11|9-0|6-11|7-2|6-5|6-0|5-7|4-8|4-7| |24wj|1-#4|60,000|9-8|10-11|8-5|8-9|7-10|7-4|6-10|5-9|5-7| |24wj|1-#5|40,000|9-10|11-2|8-7|8-11|8-0|7-6|7-0|5-10|5-8| |24wj|1-#5|60,000|12-0|13-7|10-6|10-10|9-9|9-2|8-6|7-2|6-11| |24wj|2-#4
    1-#6|40,000|11-1|12-7|9-8|10-1|9-1|8-6|7-10|6-7|6-5| |24wj|2-#4
    1-#6|60,000|15-6|17-7|13-6|14-0|12-8|11-10|10-8|8-7|8-4| |24wj|2-#5|40,000|15-6|17-11|12-8|13-4|11-6|10-7|9-7|7-10|7-7| |24wj|2-#5|60,000|DR|DR|DR|DR|DR|DR|DR|DR|DR| |24wj|Center distance_A_m, n|Center distance_A_m, n|2-4|3-0|1-9|1-11|1-6|1-4|1-2|STL|STL| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 pound per square foot = 0.0479 kPa, Grade 40 = 280 MPa, Grade 60 = 420 MPa.
    a. Where lintels are formed with waffle-grid forms, form material shall be removed, if necessary, to create top and bottom flanges of the lintel that are not less than 3 inches in
    depth (in the vertical direction), are not less than 5 inches in width for 6-inch-nominal waffle-grid forms and not less than 7 inches in width for 8-inch-nominal waffle-grid
    forms. See Figure R608.8(3). Flat form lintels shall be permitted in place of waffle-grid lintels. See Tables R608.8(2) through R608.8(5).
    b. See Table R608.3 for tolerances permitted from nominal thicknesses and minimum dimensions and spacing of cores.
    c. Table values are based on concrete with a minimum specified compressive strength of 2,500 psi. See Notes l and n. Table values are based on uniform loading. See Section
    R608.8.2 for lintels supporting concentrated loads.
    d. Deflection criterion is_L_/240, where_L_ is the clear span of the lintel in inches, or1/2 inch, whichever is less.
    e. Linear interpolation is permitted between ground snow loads.
    f. DR indicates design required. STL indicates stirrups required throughout lintel.
    g.

  • California Mechanical Code Medium relevance — show source text

    Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length||6” Min. Ground
    Clearance to
    Equipment or Panels
    4” Min.
    See 1.B.(1) on Page 2
    48” − 96” Length|| |e
    st

    84”
    Max.
    Height
    42”
    Min.
    Height
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length||6” Min. Ground
    Clearance to
    Equipment or Panels
    4” Min.
    See 1.B.(1) on Page 2
    48” − 96” Length|1/|

    Figure 1 Panel Board Construction With Struts

    Figure 2 Large Panel Board Construction With Struts

    See Note 1D on Page 2 for Fasteners

    3” Min. Galv. Rigid Steel Pipe or 6” x 6” or 8” Dia. Wood Post

    1/2” Slope

    12” Min.

    Concrete Footing

    to Equipment or Panels

    s Col2 Col3
    Panels, Boards,
    or Struts
    42”
    Min.
    Height

    t
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    6” Min.
    84”
    Max.
    eight
    48” - 96” Length    		 Panels, Boards,
    or Struts
    42”
    Min.
    Height

    t
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    6” Min.
    84”
    Max.
    eight
    48” - 96” Length    		 Panels, Boards,
    or Struts
    42”
    Min.
    Height

    t
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    6” Min.
    84”
    Max.
    eight
    48” - 96” Length
    t
    36
    6”
    8
    M
    ei    		 t
    36
    6”
    8
    M
    ei    		 Panels, Boards,
    or Struts
    t
    36
    6”
    8
    M
    ei    		 t
    36
    6”
    8
    M
    ei    		 48” - 96” Length
    t
    36
    6”
    8
    M
    ei    		 t
    36
    6”
    8
    M
    ei    		 6” Min.
  • CMC § 1127A.4.5 Medium relevance — show source text

    3. Shear force induced in a fastener or mounting device from the application of a 250-pound (1112 N) point load shall be less than the allowable lateral load of either the fastener or mounting device or the supporting structure, whichever is the smaller allowable load.

    4. Tensile force induced in a fastener by a direct tension force of a 250-pound (1112 N) point load, plus the maximum moment from the application of a 250-pound (1112 N) point load, shall be less than the allowable withdrawal load between the fastener and supporting structure.

    5. Grab bars shall not rotate within their fittings.

    1127A.4.5 Surface. A grab bar and any wall or other surface adjacent to it shall be free of any sharp or abrasive elements and shall have rounded edges.

    1127A.4.6 Spacing. When grab bars are mounted adjacent to a wall, the space between the wall and the grab bars shall be 1 [1] / 2 inches (38 mm). (See Figure 11A-9C.) The space between the grab bar and projecting objects below and at the ends shall be 1 [1] / 2 inches (38 mm) minimum. The space between the grab bar and projecting objects above shall be 12 inches (305 mm) minimum.

    Exceptions:

    1. The space between the grab bars and shower controls, shower fittings and other grab bars above shall be permitted to be 1 [1] / 2 inches (38 mm) minimum. 2. For L-shaped or U-shaped grab bars the space between the walls and the grab bar shall be 1 [1] / 2 inches (38 mm) minimum for a distance of 6 inches (152 mm) on either side of the inside corner between two adjacent wall surfaces.

    1127A.5 Bathing facilities.

    1127A.5.1 General. When common use bathing facilities are provided for residents or guests, including showers, bathtubs or lockers, at least one of each type of fixture in each facility, and not less than 1 percent of all fixtures, shall comply with this section.

    1127A.5.2 Bathtubs. Bathtubs required to be accessible shall comply with the following:

    1127A.5.2.1 Floor space. Clearance in front of bathtubs shall extend the length of the bathtub and shall be 48 inches (1219 mm) wide minimum for forward approach and 30 inches (762 mm) wide minimum for parallel approach. A lavatory complying with Section 1127A.3 shall be permitted at the control end of the clearance. When a permanent seat is provided at the head end of the bathtub, the clearance shall extend 12 inches (305 mm) minimum beyond the wall at the head end of the bathtub . (See Figure 11A- 9E.)

    1127A.5.2.2 Seat. A removable in-tub seat or a permanent seat at the head end of the tub shall be provided. The structural strength of seats and their attachments shall comply with Section 1127A.4.4. Seats shall be mounted securely and shall not slip during use.

  • CMC § 11B-65 Medium relevance — show source text

    2025 CALIFORNIA BUILDING CODE 11B-65

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMMODATIONS, COMMERCIAL BUILDINGS AND PUBLIC HOUSING

    11B-407.4.10.3 Structural strength. Allowable stresses shall not be exceeded for materials used when a vertical or horizontal force of 250 pounds (1112 N) is applied at any point on the support rail, fastener, mounting device or supporting structure.

    SECTION 11B- 408 — LIMITED-USE/LIMITED-APPLICATION ELEVATORS

    11B- 408.1 General. Limited-use/limited-application elevators shall comply with Section 11B- 408 and with ASME A17.1. They shall be passenger elevators as classified by ASME A17.1. Elevator operation shall be automatic.

    11B- 408.2 Elevator landings. Landings serving limited-use/limited-application elevators shall comply with Section 11B- 408.2.

    11B- 408.2.1 Call buttons. Elevator call buttons and keypads shall comply with Section 11B- 407.2.1.

    11B- 408.2.2 Hall signals. Hall signals shall comply with Section 11B- 407.2.2.

    11B- 408.2.3 Hoistway signs. Signs at elevator hoistways shall comply with Section 11B- 407.2.3.1.

    11B- 408.3 Elevator doors. Elevator hoistway doors shall comply with Section 11B- 408.3.

    11B- 408.3.1 Sliding doors. Sliding hoistway and car doors shall comply with Sections 11B- 407.3.1 through 11B- 407.3.3 and 11B- 408.4.1.

    11B -408.3.2 Swinging doors. Swinging hoistway doors shall open and close automatically and shall comply with Sections 11B- 404 , 11B- 407.3.2 and 11B- 408.3.2.

    11B- 408.3.2.1 Power operation. Swinging doors shall be power-operated and shall comply with ANSI/BHMA A156.19.

    11B- 408.3.2.2 Duration. Power-operated swinging doors shall remain open for 20 seconds minimum when activated.

    11B- 408.4 Elevator cars. Elevator cars shall comply with Section 11B- 408.4.

    11B- 408.4.1 Car dimensions and doors. Elevator cars shall provide a clear width 42 inches ( 1067 mm) minimum and a clear depth 54 inches ( 1372 mm) minimum. Car doors shall be positioned at the narrow ends of cars and shall provide 32 inches ( 813 mm) minimum clear width.

    Exceptions:

  • CMC § 25.4 Medium relevance — show source text

    000|83,500|155,000|

    Col1 Col2 Structural Sheathing Col4 Col5 Structural I Col7 Col8
    Thickness
    (in.)    		 A-A, A-C Marine All Other
    Grades    		 A-A, A-C Marine All Other
    Grades
    Sanded
    Plywood    		 1/4 24,000 31,000 24,000 31,000 31,000 31,000
    Sanded
    Plywood    		 11/32 25,500 33,000 25,500 33,000 33,000 33,000
    Sanded
    Plywood    		 3/8 26,000 34,000 26,000 34,000 34,000 34,000
    Sanded
    Plywood    		 15/32 38,000 49,500 38,000 49,500 49,500 49,500
    Sanded
    Plywood    		 1/2 38,500 50,000 38,500 50,000 50,000 50,000
    Sanded
    Plywood    		 19/32 49,000 63,500 49,000 63,500 63,500 63,500
    Sanded
    Plywood    		 5/8 49,500 64,500 49,500 64,500 64,500 64,500
    Sanded
    Plywood—
    continued    		 23/32 50,500 65,500 50,500 65,500 65,500 65,500
    Sanded
    Plywood—
    continued    		 3/4 51,000 66,500 51,000 66,500 66,500 66,500
    Sanded
    Plywood—
    continued    		 7/8 52,500 68,500 52,500 68,500 68,500 68,500
    Sanded
    Plywood—
    continued    		 1 73,500 95,500 73,500 95,500 95,500 95,500
    Sanded
    Plywood—
    continued    		 11/8 75,000 97,500 75,000 97,500 97,500 97,500
    For SI: 1 inch = 25.4 mm, 1 pound/inch = 0.1751 N/mm.
    a. 5-ply applies to plywood with five or more layers. For 5-ply plywood with three layers, use values for 4-ply panels.    		 For SI: 1 inch = 25.4 mm, 1 pound/inch = 0.1751 N/mm.
    a. 5-ply applies to plywood with five or more layers. For 5-ply plywood with three layers, use values for 4-ply panels.    		 For SI: 1 inch = 25.4 mm, 1 pound/inch = 0.1751 N/mm.
    a. 5-ply applies to plywood with five or more layers. For 5-ply plywood with three layers, use values for 4-ply panels.    		 For SI: 1 inch = 25.4 mm, 1 pound/inch = 0.1751 N/mm.
    a.
  • California Mechanical Code Medium relevance — show source text

    (1) on Page 2
    1/

    48” − 96” Length|||| |e
    st

    84”
    Max.
    Height
    42”
    Min.
    Height
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length|||| |e
    st

    84”
    Max.
    Height
    42”
    Min.
    Height
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length|||| |e
    st

    84”
    Max.
    Height
    42”
    Min.
    Height
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length||6” Min. Ground
    Clearance to
    Equipment or Panels
    4” Min.
    See 1.B.(1) on Page 2
    48” − 96” Length|6” Min. Ground
    Clearance to
    Equipment or Panels
    4” Min.
    See 1.B.(1) on Page 2
    48” − 96” Length| |e
    st

    84”
    Max.
    Height
    42”
    Min.
    Height
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length||6” Min. Ground
    Clearance to
    Equipment or Panels
    4” Min.
    See 1.B.(1) on Page 2
    48” − 96” Length|| |e
    st

    84”
    Max.
    Height
    42”
    Min.
    Height
    6” Min. Ground
    Clearance to
    Equipment or Panels
    36” Min.
    4” Min.
    See 1.B.(1) on Page 2
    1/

    48” − 96” Length||6” Min. Ground
    Clearance to
    Equipment or Panels
    4” Min.
    See 1.B.(1) on Page 2
    48” − 96” Length|1/|

    Figure 1 Panel Board Construction With Struts

    Figure 2 Large Panel Board Construction With Struts

    See Note 1D on Page 2 for Fasteners

    3” Min. Galv. Rigid Steel Pipe or 6” x 6” or 8” Dia. Wood Post

    1/2” Slope

    12” Min.

    Concrete Footing

    to Equipment or Panels

Frequently asked questions

How do I find the required C (discharge capacity) to start the sizing?

The C required for a vessel is determined using ASHRAE 15 procedures; § 1113.5 adopts ASHRAE 15 as the basis for required discharge capacity.

When do I use the formulas in § 1112.14 instead of a valve manufacturer’s rating?

Use § 1112.14 formulas for rupture members and fusible plugs that discharge to atmosphere. Use manufacturer/ASME ratings (ASME BPVC Section VIII.1) for pressure‑relief valves as required by § 1112.13.

Does the discharge piping affect the required device size?

Yes. Piping and fittings can reduce effective capacity through backpressure. The CMC requires the piping area be at least the valve inlet area (see § 1112.13) and contains discharge‑piping/backpressure limits (see § 1112.12.4). Always check effective capacity after piping is specified.

Which pressure value do I use in the rupture‑member formula?

For rupture members use P1 = (rated pressure in psig × 1.1) + 14.7 psia, per § 1112.14. For fusible plugs use the absolute saturation pressure at the plug’s stamped melting temperature (or refrigerant critical pressure, whichever is smaller).

Are the C and d formulas in inches and lb/min only?

The code gives the formulas in imperial units (C in lb/min, d in inches) and supplies the SI conversion for mass flow (1 lb/min = 0.00756 kg/s) in § 1112.14. Use the conversion factor when you must present SI units.

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How must safety/temperature/pressure-relief valve discharge piping be installed?

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Overpressure Protection, Relief Devices and Discharge

California Mechanical Code