What is a "high‑probability" refrigeration system?

A high‑probability system is one whose design or component locations make it likely that refrigerant released from a failed connection or component will enter the occupied space (examples include direct systems and certain open‑spray arrangements). The definition and examples are in §1103.2.1 .

Are there aggregate limits for flammable refrigerants?

Yes. The CMC limits the total amount of Group A2, B2, A3, and B3 refrigerants (excluding A2L and B2L unless otherwise addressed) to 1,100 pounds without AHJ approval; additional machinery‑room and mitigation requirements apply where flammables are used §1104.5 .

When are detectors, labeling, and access required?

Listed equipment using flammable refrigerants must be labeled and nameplated, and refrigerant detectors and mitigation measures (including ventilation and automatic actions listed in the equipment listing/ASHRAE 15) are required where releasable charge or space conditions mandate them; see §1104.6 (A2L requirements) and the related machinery‑room provisions §1106.0 for detector and access criteria .

Refrigerant classification & charge limits

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

CMC § 1103.2 High relevance — show source text
1103.2 Classification of Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 227

1103.3 Higher Flammability Refrigerants . . . . . . . . . . . . . . . . . 227

1104.0 Requirements for Refrigerant and Refrigeration System Use . . . 227

1104.1 System Selection . . . . . . . . . . . . . 227

1104.2 Refrigerant Concentration Limit (RCL) . . . . . . . . . . . . . . . . . . 227

Table 1104.1 Permissible Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 228

1104.3 Institutional Occupancies . . . . . . . 229

1104.4 Industrial Occupancies and Refrigerated Rooms . . . . . . . . . . . 229

1104.5 Flammable Refrigerants . . . . . . . . 229

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TABLE OF CONTENTS

1104.6 Group A2L Refrigerants for Human Comfort . . . . . . . . . . . . . . 229

110.4.7 Applications for Human Comfort and for Nonindustrial

Occupancies. . . . . . . . . . . . . . . . . 230

1104.8 Refrigerant Type and Purity . . . . . 230

1104.9 Changing Refrigerants . . . . . . . . . 231

1105.0 General Requirements . . . . . . . . . 231

1105.1 Human Comfort . . . . . . . . . . . . . . 231

1105.2 Supports and Anchorage . . . . . . . 231

1105.3 Access . . . . . . . . . . . . . . . . . . . . . 231

1105.4 Illumination and Service

Receptacles . . . . . . . . . . . . . . . . . 231

1105.5 Ventilation of Rooms

Containing Condensing Units . . . . 231

1105.6 Prohibited Locations . . . . . . . . . . . 232

1105.7 Condensate . . . . . . . . . . . . . . . . . 232

1105.8 Defrost . . . . . . . . . . . . . . . . . . . . . 232

1105.9 Overflows . . . . . . . . . . . . . . . . . . . 232

1105.10 Condensate, Defrost, and Overflow Disposal. . . . . . . . . . . . . 232

1105.11 Refrigerant Port Protection . . . . . . 232

1105.12 Storage . . . . . . . . . . . . . . . . . . . . . 232

1106.0 Refrigeration Machinery Rooms . . 232

1106.1 Where Required . . . . . . . . . . . . . . 232

1106.2 Refrigeration Machinery Room, General Requirements . . . . . . . . . 232
CMC § 1013.7 Medium relevance — show source text
1013.7 Unfired Pressure Vessels . . . . . . . 221

1014.0 Operation and Maintenance of

Boilers and Pressure Vessels. . . . 221

1014.1 General. . . . . . . . . . . . . . . . . . . . . 221

Table 1003.2.1 Controls and Limit Devices for

Automatic Boilers . . . . . . . . . . . . . 222

CHAPTER 11 REFRIGERATION . . . . . . . . . . . . 225

1101.0 General. . . . . . . . . . . . . . . . . . . . . 227

1101.1 Applicability. . . . . . . . . . . . . . . . . . 227

1101.2 Equipment . . . . . . . . . . . . . . . . . . 227

Part I Refrigeration Systems . . . . . . . . 227

1102.0 Refrigeration Systems . . . . . . . . . 227

1102.1 General. . . . . . . . . . . . . . . . . . . . . 227

1102.2 Ammonia Refrigeration Systems . . 227

1102.3 Refrigerants . . . . . . . . . . . . . . . . . 227

1103.0 Classification . . . . . . . . . . . . . . . . 227

1103.1 Classification of Refrigerants . . . . 227

Table 1103.1.1 Refrigerant Safety Group Classifications. . . . . . . . . . . . . . . . 227

1103.2 Classification of Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 227

1103.3 Higher Flammability Refrigerants . . . . . . . . . . . . . . . . . 227

1104.0 Requirements for Refrigerant and Refrigeration System Use . . . 227

1104.1 System Selection . . . . . . . . . . . . . 227

1104.2 Refrigerant Concentration Limit (RCL) . . . . . . . . . . . . . . . . . . 227

Table 1104.1 Permissible Refrigeration Systems . . . . . . . . . . . . . . . . . . . . 228

1104.3 Institutional Occupancies . . . . . . . 229

1104.4 Industrial Occupancies and Refrigerated Rooms . . . . . . . . . . . 229

1104.5 Flammable Refrigerants . . . . . . . . 229

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1104.6 Group A2L Refrigerants for Human Comfort . . . . . . . . . . . . . . 229

110.4.7 Applications for Human Comfort and for Nonindustrial

Occupancies. . . . . . . . . . . . . . . . . 230

1104.8 Refrigerant Type and Purity . . . . . 230

1104.9 Changing Refrigerants . . . . . . . . . 231
CMC § 1108.4 Medium relevance — show source text
3_Exception_
1108.4
|||X|||||||X||||X||||||||||| |Adopting Agency
Adopt Entire Chapter
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amended (amended sections
listed below)
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that are listed below
Chapter/Section
1104.3_Exception_
1108.4
||||||||||||||||||||||||| |Adopting Agency
Adopt Entire Chapter
Adopt Entire Chapter as
amended (amended sections
listed below)
Adopt only those sections
that are listed below
Chapter/Section
1104.3_Exception_
1108.4
||||||||||||||||||||||||| |Adopting Agency
Adopt Entire Chapter
Adopt Entire Chapter as
amended (amended sections
listed below)
Adopt only those sections
that are listed below
Chapter/Section
1104.3_Exception_
1108.4
||||||||||X||||X||||||||||| |Adopting Agency
Adopt Entire Chapter
Adopt Entire Chapter as
amended (amended sections
listed below)
Adopt only those sections
that are listed below
Chapter/Section
1104.3_Exception_
1108.4
|||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 11

REFRIGERATION

1101.0 General.

1101.1 Applicability. Part I governs the design, installation, and construction of refrigeration systems, equipment, refrigerant piping, pressure vessels, safety devices, replacement of parts, alterations, and substitution of different refrigerants. Part II governs the installation and construction of cooling

towers.

1101.2 Equipment. Equipment for refrigerant recovery, recycling, or both shall comply with UL 1963.

Part I – Refrigeration Systems.

1102.0 Refrigeration Systems.

1102.1 General. Refrigeration systems using a refrigerant other than ammonia shall comply with this chapter and ASHRAE 15. Refrigeration systems containing carbon dioxide as the refrigerant shall also comply with IIAR CO2.

1102.2 Ammonia Refrigeration Systems. Refrigeration systems using ammonia as the refrigerant shall comply with IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6 and shall not be required to comply with this chapter.

1102.3 Refrigerants. The refrigerant used shall be of a type listed in Table 1102.3 or in accordance with ASHRAE 34

where approved by the Authority Having Jurisdiction.

Exception: Lithium bromide absorption systems using water as the refrigerant.
CMC § 1104.6.4 Medium relevance — show source text
1104.6.4 Mechanical Ventilation. When the releasable charge of the refrigeration system exceeds the refrigerant concentration limit specified in Section 1104.6.1, the refrigerant charge and ventilation air flow shall be in accordance with the equipment listing and ASHRAE 15. 1104.6.5 Compressors and Pressure Vessels Located Indoors. For refrigeration compressors and pressure vessels located in an indoor space that is accessible only during service and maintenance, the refrigerant charge shall be in accordance with the equipment listing and ASHRAE 15 .

1104.6.6 Refrigerant Sensors. Refrigerant sensors required by Section 1104.6.2 shall meet the following requirements:

(1) Refrigerant sensors shall be evaluated by the testing laboratory as part of the equipment listing.

(2) Refrigerant sensors shall be located such that refrigerant will be detected if the refrigerating system is operating or not operating.

(a) For refrigerating systems that are connected to the occupied space through ductwork, refrigerant sensors shall be located within the listed equipment.

(b) For refrigerating systems that are directly connected to the occupied space without ductwork, the refrigerant sensor shall be located in the equipment in accordance with the equipment listing. Additional remote refrigerant sensors shall be permitted within the occupied space when included as part of the equipment mitigation system according to manufacturer’s instructions. {ASHRAE 15:7.6.5}

1104.7 Applications for Human Comfort and for Non- industrial Occupancies. In nonindustrial occupancies, Group A2, A3, B1, B2L, B2, and B3 refrigerants shall not be used in high-probability systems for human comfort. Use of Group A2L refrigerants used in high-probability systems for human comfort shall be in accordance with Section 1104.6.

1104.8 Refrigerant Type and Purity. Refrigerants shall be of a type specified by the equipment manufacturer. Unless otherwise specified by the equipment manufacturer, refrigerants used in new equipment shall be of purity in accordance with AHRI 700.

1104.8.1 Recovered Refrigerants. Recovered refrigerants shall not be reused except in the system from which they were removed, or as provided in Section 1104.8.2 or Section 1104.8.3. When contamination is evident by discoloration, odor, acid test results, or system history, recovered refrigerants shall be reclaimed in accordance with Section 1104.8.3 before reuse. [ASHRAE 15:7.5.1.4]

1104.8.2 Recycled Refrigerants. Recycled refrigerants shall not be reused except in systems using the same refrigerant and lubricant designation and belonging to the same owner as the systems from which they were removed. Where contamination is evident by discoloration, odor, acid test results, or system history, recycled refrigerants shall be reclaimed in accordance with Section 1104.8.3.

Exception: Drying shall not be required in order to use recycled refrigerants where water is the refrigerant, is used as an absorbent or is a deliberate additive.

[ASHRAE 15:7.5.1.5]

1104.8.3 Reclaimed Refrigerants. Used refrigerants shall not be reused in a different owner’s equipment unless tested and found to be in accordance with the
CMC § 1101.0 Medium relevance — show source text
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CHAPTER 11

REFRIGERATION

1101.0 General.

1101.1 Applicability. Part I governs the design, installation, and construction of refrigeration systems, equipment, refrigerant piping, pressure vessels, safety devices, replacement of parts, alterations, and substitution of different refrigerants. Part II governs the installation and construction of cooling

towers.

1101.2 Equipment. Equipment for refrigerant recovery, recycling, or both shall comply with UL 1963.

Part I – Refrigeration Systems.

1102.0 Refrigeration Systems.

1102.1 General. Refrigeration systems using a refrigerant other than ammonia shall comply with this chapter and ASHRAE 15. Refrigeration systems containing carbon dioxide as the refrigerant shall also comply with IIAR CO2.

1102.2 Ammonia Refrigeration Systems. Refrigeration systems using ammonia as the refrigerant shall comply with IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6 and shall not be required to comply with this chapter.

1102.3 Refrigerants. The refrigerant used shall be of a type listed in Table 1102.3 or in accordance with ASHRAE 34

where approved by the Authority Having Jurisdiction.

Exception: Lithium bromide absorption systems using water as the refrigerant.

1103.0 Classification.

1103.1 Classification of Refrigerants. Refrigerants shall be classified in accordance with Table 1102.3 or in accor dance with ASHRAE 34 where approved by the Authority Having Jurisdiction.

1103.1.1 Safety Group. Table 1102.3 classifies refrigerants by toxicity and flammability, and assigns safety groups using combinations of toxicity class and flammability class. For the purposes of this chapter, the refrigerant Groups A1, A2L, A2, A3, B1, B2L, B2, and B3 shall be considered to be individual and distinct safety groups, as shown in Table 1103.1.1. Each refrigerant is assigned into not more than one group.

TABLE 1103.1.1

REFRIGERANT SAFETY GROUP CLASSIFICATIONS

1103.2 Classification of Refrigeration Systems. Refrigeration systems shall be classified according to the degree of probability that a leakage of refrigerant will enter an occupancy-classified area in accordance with Section 1103.2.1 and Section 1103.2.2. [ASHRAE 15:5.2]

1103.2.1 High-Probability System. Systems in which the basic design, or the location of components, is such that a leakage of refrigerant from a failed connection, seal, or component will enter the occupied space shall be classified as high-probability systems. A typical high-probability system shall be one of the following:

(1) A direct system
CMC § 1103.0 Medium relevance — show source text
where approved by the Authority Having Jurisdiction.

Exception: Lithium bromide absorption systems using water as the refrigerant.

1103.0 Classification.

1103.1 Classification of Refrigerants. Refrigerants shall be classified in accordance with Table 1102.3 or in accor dance with ASHRAE 34 where approved by the Authority Having Jurisdiction.

1103.1.1 Safety Group. Table 1102.3 classifies refrigerants by toxicity and flammability, and assigns safety groups using combinations of toxicity class and flammability class. For the purposes of this chapter, the refrigerant Groups A1, A2L, A2, A3, B1, B2L, B2, and B3 shall be considered to be individual and distinct safety groups, as shown in Table 1103.1.1. Each refrigerant is assigned into not more than one group.

TABLE 1103.1.1

REFRIGERANT SAFETY GROUP CLASSIFICATIONS

1103.2 Classification of Refrigeration Systems. Refrigeration systems shall be classified according to the degree of probability that a leakage of refrigerant will enter an occupancy-classified area in accordance with Section 1103.2.1 and Section 1103.2.2. [ASHRAE 15:5.2]

1103.2.1 High-Probability System. Systems in which the basic design, or the location of components, is such that a leakage of refrigerant from a failed connection, seal, or component will enter the occupied space shall be classified as high-probability systems. A typical high-probability system shall be one of the following:

(1) A direct system

(2) An indirect open spray system in which the refrigerant is capable of producing pressure that is more than the secondary coolant. [ASHRAE 15:5.2.1]

1103.2.2 Low-Probability System. Systems in which the basic design, or the location of the components, is such that a leakage of refrigerant from a failed connection, seal, or component cannot enter the occupied space shall be classified as low-probability systems. A typical low-probability system shall be one of the following:

(1) An indirect closed system

(2) Double indirect system

(3) An indirect open spray system. In a low-probability indirect open spray system, the secondary coolant pressure remains more than the refrigerant pressure in operating and standby conditions. [ASHRAE 15:5.2.2]

1103.3 Higher Flammability Refrigerants. Group A3 and B3 refrigerants shall not be used except where approved by the Authority Having Jurisdiction.

Exceptions:

(1) Laboratories with more than 100 square feet (9.29 m [2] ) of space per person.

(2) Industrial occupancies.

(3) Listed self-contained systems containing not more than 0.331 pounds (0.150 kg) of Group A3 refrigerant, provided that the equipment is installed in accordance with the listing and the manufacturer’s installation instructions. [ASHRAE 15:7.5.3]

1104.0 Requirements for Refrigerant and Refrigera- tion System Use.
CMC § 608.1 Medium relevance — show source text
SECTION 608—MECHANICAL REFRIGERATION

[M] 608.1 Scope. Refrigeration systems shall be installed in accordance with the California Mechanical Code .

608.1.1 Refrigerants other than ammonia. Where a refrigerant other than ammonia is used, refrigeration systems and the buildings in which such systems are installed shall be in accordance with ASHRAE 15.

608.1.2 Ammonia refrigeration. Refrigeration systems using ammonia refrigerant and the buildings in which such systems are installed shall comply with IIAR 2 for system design; IIAR 6 for inspection, testing and maintenance; and IIAR 7 for operating procedures. Decommissioning of ammonia refrigeration systems shall comply with IIAR 8, and engineering practices for existing ammonia refrigeration systems shall be in accordance with IIAR 9.

608.2 Permits. An operational permit shall be obtained for refrigeration systems as set forth in Section 105.5.46.

[M] 608.3 Refrigerants. The use and purity of new, recovered and reclaimed refrigerants shall be in accordance with the California Mechanical Code .

[M] 608.4 Refrigerant classification. Refrigerants shall be classified in accordance with the California Mechanical Code .

[M] 608.5 Change in refrigerant type. A change in the type of refrigerant in a refrigeration system shall be in accordance with the California Mechanical Code .

608.6 Access. Access to refrigeration systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant shall be provided for the fire department at all times as required by the fire code official.

608.7 Testing of equipment. Refrigeration equipment and systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant shall be subject to periodic testing in accordance with Section 608.7.1. Records of tests shall be maintained. Tests of emergency devices or systems required by this chapter shall be conducted by persons trained and qualified in refrigeration systems.

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BUILDING SERVICES AND SYSTEMS

608.7.1 Periodic testing. The following emergency devices or systems shall be periodically tested in accordance with the manufacturer’s instructions and as required by the fire code official.
1. Treatment and flaring systems.
2. Valves and appurtenances necessary to the operation of emergency refrigeration control boxes.
3. Fans and associated equipment intended to operate emergency ventilation systems.
4. Detection and alarm systems.
608.8 Emergency signs. Refrigeration units or systems having a refrigerant circuit containing more than 220 pounds (100 kg) of Group A1 or 30 pounds (14 kg) of any other group refrigerant shall be provided with approved emergency signs, charts and labels in accordance with NFPA 704. Hazard signs shall be in accordance with the California Mechanical Code for the classification of refrigerants listed therein.

608.9 Refrigerant detection. Machinery rooms shall be provided with a refrigerant detector with an audible and visible alarm. Where ammonia is used as the refrigerant, detection shall comply with IIAR 2. For refrigerants other than ammonia, refrigerant detection shall comply with Section 608.9.1.
CMC § 1114.2 Medium relevance — show source text
(2) Lithium bromide absorption system using water as the refrigerant.

1114.2 Design Requirements. Flaring devices shall be designed to incinerate the entire discharge. The products of refrigerant incineration shall not pose health or environmental hazards. Incineration shall be automatic upon initiation of discharge, shall be designed to prevent blow-back, and shall not expose structures or materials to the threat of fire. Standby fuel, such as LP-Gas, and standby power shall have the capacity to operate for one and a half times the required time for complete incineration of the charge.

1114.3 Testing. Flaring systems shall be tested to demonstrate their safety and effectiveness. A report from an approved agency shall be submitted detailing the emission products from the system as installed.

1115.0 Labeling and Identification.

1115.1 General. In addition to labels required elsewhere in this chapter, a refrigeration system shall be provided with identification labels in accordance with Section 1115.2

through Section 1115.5.

1115.2 Volume and Type. A condenser, receiver, absorber, accumulator and similar equipment having an internal volume of more than 3 cubic feet (0.1 m [3] ) and containing refrigerant shall be equipped with a permanent label setting forth the type of refrigerant in such vessel.

1115.3 Permanent Sign. In a refrigeration machinery room and for a direct refrigerating system of more than 10 horsepower (7.5 kW), there shall be a permanent sign at an approved location giving the following information:

(1) Name of contractor installing the equipment.

(2) Name and number designation of refrigerant in system.

(3) Pounds of refrigerant in system.

1115.4 Marking of Pressure-Relief Devices. Pressurerelief valves for refrigerant containing components shall be set and sealed by the manufacturer or an assembler as defined in ASME BPVC Section VIII.1. Each pressure relief valve shall be marked by the manufacturer or assembler with the data required in ASME BPVC Section VIII.1.

Exception: Relief valves for systems with design pressures of 15 pounds-force per square inch gauge (psig) (103 kPa gauge) or less shall be marked by the manufacturer with the pressure setting capacity. [ASHRAE 15:9.6.1]

1115.4.1 Rupture Members. Rupture members for refrigerant pressure vessels shall be marked with the data required in accordance with ASME BPVC Section VIII.1. [ASHRAE 15:9.6.2]

1115.4.2 Fusible Plugs. Fusible plugs shall be marked with the melting temperatures in °F (°C).

[ASHRAE 15:9.6.3]

1115.5 Nameplate. Each self-contained system and each separate condensing unit, compressor, or compressor unit sold for field assembly in a refrigerating system shall carry a nameplate marked with the manufacturer’s name, nationally registered trademark or trade name, identification num

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REFRIGERATION
CMC § 1104.6.2.2 Medium relevance — show source text
1104.6.2.2 Labeling. A label indicating a flammable refrigerant is used shall be placed adjacent to service ports and other locations where service involving components containing refrigerant is performed, as specified by the product listing.

[ASHRAE 15:7.6.2.2]

1104.6.2.3 Refrigerant Detection Systems. Refrigerant detection systems shall be in accordance with the listing and ASHRAE 15.

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REFRIGERATION

1104.6.2.4 Refrigerant Concentration Above Limit. When the refrigerant detection system senses a refrigerant exceeding its setpoint, the following actions shall be taken:

(1) The supply air fan of the equipment shall activate with a minimum airflow rate specified by the manufacturer.

(2) Turn off the compressor and all other electrical devices, excluding the control power transformers, control systems, and the supply air fan. The supply air fan shall continue to operate for at least five minutes after the refrigerant detection system has sensed a drop in the refrigerant concentration below the value specified in Section 1104.6.6(b).

Exception: The compressor operation shall not be turned off when the compressor operation reduces the leak rate or the total amount of

released refrigerant to the indoor space.

(3) Any device that controls airflow located within the product or in ductwork that supplies air to the occupied space shall be fully open. Any device that controls airflow shall be listed.

(4) Mitigation action required by the equipment listing shall be initiated. {ASHRAE 15:7.6.2.4} 1104.6.3 Ignition Sources Located in Ductwork. Open-flame-producing devices shall not be permanently installed in the ductwork that serves the space. Unclassified electrical devices shall not be located within the ductwork that serves the space. Devices containing hot surfaces exceeding 1290°F (700°C) shall not be located in the ductwork that serves the space unless there is a minimum airflow of 200 ft/min (1.0 m/s) across the heating device(s) and there is proof of airflow before the heating device(s) is energized. [ASHRAE 15:7.6.37.6.3.3]

1104.6.4 Mechanical Ventilation. When the releasable charge of the refrigeration system exceeds the refrigerant concentration limit specified in Section 1104.6.1, the refrigerant charge and ventilation air flow shall be in accordance with the equipment listing and ASHRAE 15. 1104.6.5 Compressors and Pressure Vessels Located Indoors. For refrigeration compressors and pressure vessels located in an indoor space that is accessible only during service and maintenance, the refrigerant charge shall be in accordance with the equipment listing and ASHRAE 15 .

1104.6.6 Refrigerant Sensors. Refrigerant sensors required by Section 1104.6.2 shall meet the following requirements:

(1) Refrigerant sensors shall be evaluated by the testing laboratory as part of the equipment listing.

(2) Refrigerant sensors shall be located such that refrigerant will be detected if the refrigerating system is operating or not operating.
CMC § 1104.0. Medium relevance — show source text
4 only|Any|Any| |E|Group A1 or A2L4 only|Any|Any| |F-1|Group A12 or A2L2,4 only|Any|Any| |F-2|Any2|Any|Any| |H-1|Any|Any|Any| |H-2|Any|Any|Any| |H-3|Any|Any|Any| |H-4|Group A1 or A2L4 only|Any|Any| |H-5|Group A1 or A2L4 only|Any|Any| |I-1|None|Any|Any| |I-2|Group A1 or A2L4 only|Any|Any| |I-3|None|Any|Any| |I-4|Group A1 or A2L4 only|Any|Any| |M|Group A12 or A2L2,4 only|Any|Any| |R-1|Group A1 or A2L4 only|Any|Any| |R-2|Group A1 or A2L4 only|Any|Any| |R-3|Group A1 or A2L4 only|Any|Any| |R-4|Group A1 or A2L4 only|Any|Any| |S-1|Group A12 or A2L2,4 only|Any|Any| |S-2|Any2|Any|Any| |U|Any|Any|Any|

Notes: 1 See Section 1104.0. 2 A refrigerant shall be permitted to be used within a high-probability system where the room or space is in accordance with Section 1104.4. 3 Occupancy classifications are defined in the building code. 4 See Section 1104.6 for requirements applicable to A2L equipment.

independent circuit of high-probability systems shall not exceed the amounts shown in Table 1102.3, except as provided in Section 1104.3, Section 1104.4, and Section 1104.6. The volume of occupied space shall be determined in accordance with Section 1104.2.1 through Section 1104.2.3. Exceptions: (1) Listed equipment in locations other than public corridors and lobbies containing not more than 6.6 pounds (2.99 kg) of refrigerant, regardless of its refrigerant safety classification, provided the equipment is installed in accordance with the listing and with the manufacturer’s installation instructions.

(2) Listed equipment for use in laboratories with more than 100 square feet (9.29 m [2] ) of space per person, regardless of the refrigerant safety classification, provided that the equipment is installed in accordance with the listing and the manufacturer’s installation instructions. {ASHRAE 15:7.2}

1104.2.1 Volume Calculations. The volume used to convert from refrigerant concentration limits to refrigerating system quantity limits for refrigerants in Section 1104.2 shall be based on the volume of space to which refrigerant disperses in the event of a refrigerant leak.

[ASHRAE 15:7.3]
CMC § 1104.0. Medium relevance — show source text
4 only|Any|Any| |S-2|Any2|Any|Any| |U|Any|Any|Any|

Notes: 1 See Section 1104.0. 2 A refrigerant shall be permitted to be used within a high-probability system where the room or space is in accordance with Section 1104.4. 3 Occupancy classifications are defined in the building code. 4 See Section 1104.6 for requirements applicable to A2L equipment.

independent circuit of high-probability systems shall not exceed the amounts shown in Table 1102.3, except as provided in Section 1104.3, Section 1104.4, and Section 1104.6. The volume of occupied space shall be determined in accordance with Section 1104.2.1 through Section 1104.2.3. Exceptions: (1) Listed equipment in locations other than public corridors and lobbies containing not more than 6.6 pounds (2.99 kg) of refrigerant, regardless of its refrigerant safety classification, provided the equipment is installed in accordance with the listing and with the manufacturer’s installation instructions.

(2) Listed equipment for use in laboratories with more than 100 square feet (9.29 m [2] ) of space per person, regardless of the refrigerant safety classification, provided that the equipment is installed in accordance with the listing and the manufacturer’s installation instructions. {ASHRAE 15:7.2}

1104.2.1 Volume Calculations. The volume used to convert from refrigerant concentration limits to refrigerating system quantity limits for refrigerants in Section 1104.2 shall be based on the volume of space to which refrigerant disperses in the event of a refrigerant leak.

[ASHRAE 15:7.3]

1104.2.2 Nonconnecting Spaces. Where a refrigerating system, or a part thereof, is located in one or more enclosed occupied spaces that do not connect through permanent openings or HVAC ducts, the volume of the smallest occupied space shall be used to determine the refrigerant quantity limit in the system. Where different stories and floor levels connect through an open atrium or mezzanine arrangement, the volume to be used in calculating the refrigerant quantity limit shall be determined by multiplying the floor area of the lowest space by 8.2 feet (2499 mm). [ASHRAE 15:7.3.1]

228 2025 CALIFORNIA MECHANICAL CODE

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REFRIGERATION

1104.2.3 Ventilated Spaces. Where a refrigerating system, or a part thereof, is located within an air handler, in an air distribution duct system, or in an occupied space served by a mechanical ventilation system, the entire air distribution system shall be analyzed to determine the worst-case distribution of leaked refrigerant. The worst case or the smallest volume in which the leaked refrigerant disperses shall be used to determine the refrigerant quantity limit in the system, subject to the criteria in accordance with Section 1104.2.3.1 through Section 1104.2.3.3. [ASHRAE 15:7.3.2]

CMC § 90.1 Medium relevance — show source text

[ASHRAE 90.1: TABLE 6.4.3.4.3]

Col1	OUTDOOR AIR INTAKE (CFM/ft2)	Col3	EXHAUST/RELIEF (CFM/ft2)	Col5
CLIMATE ZONE	NONMOTORIZED1	MOTORIZED	NONMOTORIZED3	MOTORIZED
0, 1, 2	0, 1, 2	0, 1, 2	0, 1, 2	0, 1, 2
Any height	20	4	20	4
3	3	3	3	3
Any height	20	10	20	10
4, 5B, 5C	4, 5B, 5C	4, 5B, 5C	4, 5B, 5C	4, 5B, 5C
Fewer than three stories	204	10	20	10
Three or more stories	204	10	204	10
5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8
Fewer than three stories	204	4	20	4
Three or more stories	204	4	204	4

For SI units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.00047 m [3] /s, 1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per minute per square foot = 5.08 [(L/s)/m [2] ], 1 inch water gauge = 0.249 kPa

Notes:

1 When tested in accordance with AMCA 500D.

2 Dampers smaller than 12 inches (305 mm) in height, width, or diameter need not be tested but shall be of the same design and construction as the smallest tested damper meeting the listed leakage rate requirement.

3 Nonmotorized dampers smaller than 24 inches (610 mm) in height, width, or diameter shall be permitted to have a leakage rate of 40 CFM/ft 2 [0.203 (m 3 /s)/m 2 ].

4 Where permitted by Section E 503.4.6.4.1, exception 2.

2025 CALIFORNIA MECHANICAL CODE 425

APPENDIX E

(2) Systems serving zones where humidity levels are required to be maintained with precision of not more than ±5 percent relative humidity to comply with applicable codes or accreditation standards or as approved by the Authority Having Jurisdiction.

[ASHRAE 90.1:6.4.3.6.2]

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