CMC · California Mechanical Code
When does a refrigeration system follow ASHRAE 15 versus IIAR (ammonia) standards?
If your system uses ammonia, follow the IIAR standards listed in the CMC (**§ 1102.2**); if it uses any other refrigerant, follow Chapter 11 and **ASHRAE 15** (and for CO2 also follow IIAR CO2) — see **§ 1102.1**.
Last reviewed: July 6, 2026
What the code requires — plain English
- If the refrigerant is not ammonia, the system must follow Chapter 11 of the CMC and ASHRAE 15 — see § 1102.1.
- If the refrigerant is ammonia, the system must follow the IIAR standards listed and is not required to comply with Chapter 11 — see § 1102.2.
The single most important rule: If it's ammonia, follow IIAR; if it's any other refrigerant, follow Chapter 11 and ASHRAE 15. (See § 1102.1 and § 1102.2.)
Requirements in detail
Decision dimensions
The table below shows the decision-relevant dimensions, the required standard, and where that rule appears in the CMC.
| Decision factor | Required standard(s) | Notes / immediate consequence | Code Reference |
|---|---|---|---|
| Refrigerant = ammonia | IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, IIAR 6 | Ammonia systems are not required to comply with Chapter 11 (i.e., the rest of this chapter). Follow IIAR documents for design, inspection, testing, maintenance, and related matters. | § 1102.2 — |
| Refrigerant ≠ ammonia | CMC Chapter 11 and ASHRAE 15 | All non-ammonia refrigeration systems must comply with the chapter and ASHRAE 15. | § 1102.1 — |
| Refrigerant = carbon dioxide (CO2) | CMC Chapter 11, ASHRAE 15, and IIAR CO2 | CO2 systems are specifically required to comply with IIAR CO2 in addition to ASHRAE 15. | § 1102.1 — |
Key defined terms and thresholds (first appearances)
- Ammonia — the refrigerant that triggers IIAR-based compliance (see § 1102.2).
- ASHRAE 15 — the referenced standard for refrigeration safety for non-ammonia refrigerants (see § 1102.1).
- IIAR (e.g., IIAR 2, IIAR 3, etc.) — the industry standards that govern ammonia refrigeration equipment and practice (see § 1102.2).
What “not required to comply with this chapter” means
- For ammonia systems, the CMC authoritatively points the designer/operator to the IIAR suite instead of the Chapter 11 requirements; the Chapter’s provisions do not apply as the mandatory baseline for those systems. See § 1102.2.
Exceptions & special cases
- Carbon dioxide (CO2) systems: Although CO2 is not ammonia, § 1102.1 requires CO2 systems to comply with IIAR CO2 in addition to ASHRAE 15 and Chapter 11 — treat CO2 as a special hybrid case.
- The CMC text includes specific lists of IIAR documents for ammonia (IIAR 2, 3, IIAR/ANSI 4, 5, 6). Always confirm the exact IIAR editions referenced by the Authority Having Jurisdiction (AHJ) or the adopted code edition. See § 1102.2.
- If your design uses an unusual refrigerant not listed in Table 1102.3, the CMC references ASHRAE 34 for classification where approved by the AHJ (see § 1102.3).
Common mistakes
- Assuming Chapter 11 applies to ammonia systems. The code explicitly directs ammonia systems to IIAR standards and relieves them from Chapter 11 compliance — § 1102.2.
- Treating CO2 as “just another non-ammonia refrigerant.” CO2 must also meet IIAR CO2 in addition to ASHRAE 15 — § 1102.1.
- Not verifying the AHJ-approved editions of ASHRAE or IIAR standards. The CMC ties compliance to those standards but AHJs can approve editions or alternative references — consult the AHJ and the CMC adoption language (see § 1102.3 for refrigerant listings).
Worked example — concrete scenario
Scenario A: A cold-storage plant uses R‑717 (ammonia) in its primary refrigeration loop.
- Decision: Because the refrigerant is ammonia, design, installation and maintenance must follow the IIAR standards listed by the CMC (IIAR 2, 3, IIAR/ANSI 4, 5, 6). The plant is not required to comply with Chapter 11’s alternative provisions. Cite: § 1102.2.
Scenario B: A supermarket installs a new rooftop condensing unit charged with R‑448A (a non‑ammonia refrigerant).
- Decision: The system must comply with CMC Chapter 11 and ASHRAE 15, per § 1102.1. The designer must apply the Chapter 11 machinery‑room, ventilation, detector, and concentration‑limit rules together with ASHRAE 15 requirements. Cite: § 1102.1.
Scenario C: A laboratory installs a transcritical CO2 cascade system.
- Decision: Follow CMC Chapter 11 and ASHRAE 15, and also comply with IIAR CO2 as required in § 1102.1. Confirm detector, ventilation, and AHJ expectations for CO2 per IIAR CO2 guidance.
Related provisions (CMC sections)
- § 1102.1 — General rule for refrigerants other than ammonia; CO2 special requirement.
- § 1102.2 — Ammonia refrigeration systems: IIAR standards apply and Chapter 11 is not required for ammonia.
- § 1102.3 — Refrigerant listing and references (Table 1102.3 / ASHRAE 34 approval by AHJ).
- § 1103.1 — Refrigerant classification (safety groups and Table 1103.1.1).
(If you want, I can extract the exact text of Table 1102.3 and Table 1103.1.1 or map a given refrigerant to its safety group and the specific Chapter 11 concentration limits — tell me the refrigerant or upload the system spec.)
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 607.4.1 High relevance — show source text
607.4.1 Design standards. The design, fabrication and assembly of system components shall be suitable for the working pressures, temperatures and structural stresses to be encountered by the components.
607.4.2 Components in contact with heated oil. System components that come in contact with heated cooking oil shall be rated for the maximum operating temperatures expected in the system.
607.5 Tank venting. Normal and emergency venting shall be provided for cooking oil storage tanks.
607.5.1 Normal vents. Normal vents shall be located above the maximum normal liquid line, and shall have a minimum effective area not smaller than the largest filling or withdrawal connection. Normal vents shall be permitted to vent inside the building.
607.5.2 Emergency vents. Emergency relief vents shall be located above the maximum normal liquid line, and shall be in the form of a device or devices that will relieve excessive internal pressure caused by an exposure fire. For nonmetallic tanks, the emergency relief vent shall be allowed to be in the form of construction. Emergency vents shall be permitted to vent inside the building.
607.6 Heating of cooking oil. Electrical equipment used for heating cooking oil in cooking oil storage systems shall be listed to UL 499 and shall comply with the California Electrical Code . Use of electrical immersion heaters shall be prohibited in nonmetallic tanks.
607.7 Electrical equipment. Electrical equipment used for the operation of cooking oil storage systems shall comply with the Cali- fornia Electrical Code.
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.
CMC § 608.1 High 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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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.
- Treatment and flaring systems.
- Valves and appurtenances necessary to the operation of emergency refrigeration control boxes.
- Fans and associated equipment intended to operate emergency ventilation systems.
- 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 § 1101.0 High 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 § 1108.4 High relevance — show source text
3_Exception_
1108.4
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amended (amended sections
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1104.3_Exception_
1108.4
||||||||||||||||||||||||| |Adopting Agency
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amended (amended sections
listed below)
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that are listed below
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1104.3_Exception_
1108.4
||||||||||||||||||||||||| |Adopting Agency
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amended (amended sections
listed below)
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that are listed below
Chapter/Section
1104.3_Exception_
1108.4
||||||||||X||||X||||||||||| |Adopting Agency
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amended (amended sections
listed below)
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that are listed below
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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.
2025 CALIFORNIA MECHANICAL CODE 225
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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.
California Mechanical Code Medium relevance — show source text
|
Fail| |b.
Force the time between 9:00 p.m. and 9:00 a.m. and simulate a partial or no charge of the tank and
simulate no cooling load by setting the indoor temperature setpoint higher than the ambient tempera-
ture. Verify that the TES system starts charging (storing energy).|
Pass| |b.
Force the time between 9:00 p.m. and 9:00 a.m. and simulate a partial or no charge of the tank and
simulate no cooling load by setting the indoor temperature setpoint higher than the ambient tempera-
ture. Verify that the TES system starts charging (storing energy).|
Fail| |c.
Force the time to be between 6:00 p.m. and 9:00 p.m. and simulate a partial charge on the tank and
simulate a cooling load by setting the indoor temperature set point lower than the ambient tempera-
ture. Verify that the TES system starts discharging.|
Pass| |c.
Force the time to be between 6:00 p.m. and 9:00 p.m. and simulate a partial charge on the tank and
simulate a cooling load by setting the indoor temperature set point lower than the ambient tempera-
ture. Verify that the TES system starts discharging.|
Fail| |d.
Force the time to be between noon and 6:00 p.m. and simulate a cooling load by lowering the indoor
air temperature set point below the ambient temperature. Verify that the tank starts discharging and
the compressor is off. For systems designed to meet partial loads the system should be run until the
TES storage is fully depleted. The number of hours of operation must meet or exceed the designed
operational hours for the system.|
Pass| |d.
Force the time to be between noon and 6:00 p.m. and simulate a cooling load by lowering the indoor
air temperature set point below the ambient temperature. Verify that the tank starts discharging and
the compressor is off. For systems designed to meet partial loads the system should be run until the
TES storage is fully depleted. The number of hours of operation must meet or exceed the designed
operational hours for the system.|
Fail| |e.
Force the time to be between 9:00 a.m. to noon, and simulate a cooling load by lowering the indoor
air temperature set point below the ambient temperature. Verify that the tank does not discharge and
the cooling load is met by the compressor only.|
Pass| |e.
Force the time to be between 9:00 a.m. to noon, and simulate a cooling load by lowering the indoor
air temperature set point below the ambient temperature. Verify that the tank does not discharge and
the cooling load is met by the compressor only.|
Fail| |f.
Force the time to be between 9:00 p.m. and 9:00 a.m. and simulate a full tank charge by changing the
output of the sensor to the EMS. Verify that the tank charging is stopped.|
Pass| |f.
Force the time to be between 9:00 p.m. and 9:00 a.m.CMC § 1102.3 Medium relevance — show source text
A major milestone reached in the industry was the introduction of lower flammability refrigerants such as A2L and B2L. The industry’s concerns to address lower Global Warming Potential (GWP) refrigerants led to the development of these lower flammability refrigerants. Chapter 11 does not only include these lower flammability refrigerants in Table 1102.3, but it also contains specific A2L and B2L provisions to address the precautions necessary for the proper use of these products. In particular, high-probability systems using A2L refrigerants for human comfort applications are covered by provisions which include refrigerant concentration limits, mechanical ventilation, ignition sources, compressors and pressure vessels, and refrigerant sensors.
In addition, Chapter 11 addresses other minimum requirements for refrigeration systems such as refrigeration machinery rooms (including ventilation), relief valves, and pressure vessels. Apart from refrigerants, the chapter also addresses minimum requirements for systems that use other mediums such as ammonia and brine systems. For ammonia systems, such systems are required to comply with IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6.
Chapter 12 Hydronics. Chapter 12 regulates hydronic systems that are part of heating, cooling, ventilation, and conditioning systems. Such piping systems include steam, hot water, radiant heating and cooling, chilled water, steam condensate, condenser water, ground source heat pump systems, snow and ice melt systems, ambient temperature loops, and district ambient temperature loops. Provisions within this chapter addressing ground source heat pumps and ambient temperature loops apply to the hydronic portions of the system. Geothermal energy systems, including ground source heat pumps and ambient temperature loops, are regulated by Chapter 17.
Materials for piping and tubing must meet the working temperature and pressure of the system. In addition, materials must be compatible with the transfer medium to prevent deformation, bursting, or any chemical action between the material and the transfer medium. The allowable joining methods for piping or tubing are provided for application and enforcement purposes.
Chapter 13 Fuel Gas Piping. Chapter 13 regulates gas piping systems in a building, structure or within the property lines of buildings up to 5 psi. Gas piping systems must supply the minimum volume of gas required by each gas appliance to perform their proper operation under working conditions without exceeding the maximum pressure specified by each manufacturer. Because of the hazards associated with fuel gas, it is important to ensure the gas system has been inspected and tested, and that it is safe to turn on the gas supply to the building.
Chapter 14 Process Piping. Chapter 14 regulates process piping that typically is found in refineries. Process piping is considered the piping or tubing portion that transports liquid or gas, which is used directly in research, laboratory, or production process. This chapter may be used with another chapter of the code. For example, refrigeration piping, fuel gas piping, or fuel oil piping may need to comply with this chapter for process piping and the applicable chapter for materials, design, and installation.
Chapter 15 Solar Energy Systems. Chapter 15 refers the user to the Uniform Solar, Hydronics and Geothermal Code (USHGC) for solar energy system requirements. The USHGC contains comprehensive design, installation, and construction requirements for all types of solar thermal systems, such as drainback, thermosiphon, open-loop, and closed-loop systems. The USHGC also addresses installation of solar photovoltaic (PV) systems including array circuit(s), inverter(s), and controller(s) for such systems.
CMC § 1102.3 Medium relevance — show source text
Chapter 10 Boilers and Pressure Vessels. Chapter 10 regulates the construction, installation, operation, repair, and alteration of boilers and pressure vessels. The safety provisions within this chapter address controls and limit devices for automatic boilers, methods of determining expansion tank capacities, discharge piping, relief valves, shutoff valves, gas-pressure and combustion regulators, and inspections and tests. Potable water heaters are free from the requirements of Chapter 10 as they are within the scope of the Uniform Plumbing Code (UPC).
Pressure vessels store large amounts of energy and must comply with ASME Boiler and Pressure Vessel Code (BPVC) Section VIII.1. The stored energy must be contained to prevent disastrous failures. Boilers must comply with ASME BPVC Section I, ASME BPVC Section IV, or NFPA 85. Installing a safety relief valve and expansion tank prevents pressures in the tank from exceeding the design threshold.
Chapter 11 Refrigeration. Chapter 11 regulates the design, installation, and construction requirements of refrigeration systems and the installation and construction of cooling towers. Refrigeration is a method used for achieving heat transfer to cool spaces. Refrigerants are the most common medium used to transfer the heat energy from the low-temperature level to the high-temperature level. Table
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FORMAT OF THE UNIFORM MECHANICAL CODE
1102.3 lists the most commonly used refrigerants and is labeled by a number. The concentration limits provided in Table 1102.3 are useful for the quantity of refrigerant required to cool a volume of space safely.
A major milestone reached in the industry was the introduction of lower flammability refrigerants such as A2L and B2L. The industry’s concerns to address lower Global Warming Potential (GWP) refrigerants led to the development of these lower flammability refrigerants. Chapter 11 does not only include these lower flammability refrigerants in Table 1102.3, but it also contains specific A2L and B2L provisions to address the precautions necessary for the proper use of these products. In particular, high-probability systems using A2L refrigerants for human comfort applications are covered by provisions which include refrigerant concentration limits, mechanical ventilation, ignition sources, compressors and pressure vessels, and refrigerant sensors.
In addition, Chapter 11 addresses other minimum requirements for refrigeration systems such as refrigeration machinery rooms (including ventilation), relief valves, and pressure vessels. Apart from refrigerants, the chapter also addresses minimum requirements for systems that use other mediums such as ammonia and brine systems. For ammonia systems, such systems are required to comply with IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6.
Chapter 12 Hydronics. Chapter 12 regulates hydronic systems that are part of heating, cooling, ventilation, and conditioning systems. Such piping systems include steam, hot water, radiant heating and cooling, chilled water, steam condensate, condenser water, ground source heat pump systems, snow and ice melt systems, ambient temperature loops, and district ambient temperature loops. Provisions within this chapter addressing ground source heat pumps and ambient temperature loops apply to the hydronic portions of the system. Geothermal energy systems, including ground source heat pumps and ambient temperature loops, are regulated by Chapter 17.
CMC § 608.13.7 Medium relevance — show source text
608.13.7 Ammonia diffusion systems. Ammonia diffusion systems shall include a tank containing 1 gallon of water for each pound of ammonia (8.3 L of water for each 1 kg of ammonia) that will be released in 1 hour from the largest relief device connected to the discharge pipe. The water shall be prevented from freezing. The discharge pipe from the pressure relief device shall distribute ammonia in the bottom of the tank, but not lower than 33 feet (10 058 mm) below the maximum liquid level. The tank shall contain the volume of water and ammonia without overflowing.
608.14 Mechanical ventilation exhaust. Exhaust from mechanical ventilation systems serving refrigeration machinery rooms containing flammable, toxic or highly toxic refrigerants, other than ammonia, capable of exceeding 25 percent of the LFL or 50 percent of the IDLH shall be equipped with approved treatment systems to reduce the discharge concentrations to those values or lower.
Exception: Refrigeration systems containing Group A2L complying with Section 608.18.
608.15 Notification of refrigerant discharges. The fire code official shall be notified immediately when a discharge becomes reportable under state, federal or local regulations in accordance with Section 5003.3.1.
608.16 Records. A record of refrigerant quantities brought into and removed from the premises shall be maintained.
[M] 608.17 Electrical equipment. Where refrigerant of Groups A2, A3, B2 and B3, as defined in the California Mechanical Code, are used, refrigeration machinery rooms shall conform to the Class I, Division 2, hazardous location classification requirements of the California Electrical Code.
Exception: Ammonia machinery rooms that are provided with ventilation in accordance with Section 1101.1.2 of the California Mechanical Code .
[M] 608.18 Group A2L and B2L refrigerant. Machinery rooms for Group A2L and B2L refrigerant shall comply with Sections 1106.4.1 through 1106.4.3 of the California Mechanical Code .
608.18.1 Elevated temperatures. Open flame-producing devices or continuously operating hot surfaces over 1,290°F (700°C) shall not be permanently installed in the room.
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[M] 608.18.2 Refrigerant detector. In addition to the requirements of Section 1105.3 of the California Mechanical Code, refrigerant detectors shall signal an alarm and activate the ventilation system in accordance with the response time specified in Table 608.18.2.
TABLE 608.18.2—GROUP A2L AND B2L DETECTOR ACTIVATION Col2 Col3 Col4 Col5 ACTIVATION LEVEL MAXIMUM
RESPONSE TIME (seconds)ASHRAE 15
VENTILATION LEVELALARM RESET ALARM TYPE Less than or equal to the OEL in Table 1103.1 of the
California Mechanical Code300 1 Automatic Trouble Less than or equal to the refrigerant concentration level
in Table 1103.1 of the_California Mechanical Code_15 2 Manual Emergency 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
The material for the pin terminals is on Table 41. Copper Rod-Soft Drawn, Tinned, Aluminum Connector EC Grade, Untinned
Connector is supplied pre-filled with inhibitor and sealed.
Connector is supplied pre-filled with inhibitor and sealed.
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
- To make straight connections of insulated aluminum secondary neutral to bare copper neutral, see Note 10 Page 7.
- To connect aluminum primary stress cone termination to terminal tap connector or cutout.
- 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 § 1220.4.2 Medium relevance — show source text
8|1220.4.2 – 1220.4.6| |1221.7|1221.6| |1308.2 – 1308.4.1|1308.3 – 1308.5.1| |Table 1308.3.1|Table 1308.4.1| |1308.4.2|1308.5.2| |1308.4.2.2 – 1308.6.4|1308.5.2.1 – 1308.7.3| |Table 1308.4.6.2|Table 1308.5.6.2| |1308.6.5 – 1308.13.1|1308.7.7 – 1308.14.1| |1312.1.2 – 1312.1.3|1312.1.1 – 1312.1.2| |Chapter 17|Appendix F| |Chapter 18|Chapter 17| |D 103.2|D 103.1| |E 503.5.6.7|E 503.5.6.6| |E 503.5.7.2 – E 503.5.7.6|E 503.5.7.1 – E 503.5.7.5| |Table E 503.5.7.2|Table E 503.5.7.1| |Table E 503.5.7.6|Table E 503.5.7.5| |Table E 503.5.10.1.2(1)|Table E 503.5.10(1)| |Table E 503.5.10.1.2(2)|Table E 503.5.10(2)| |E 503.5.10.1.2|E 503.5.10| |E 503.5.10.2 – E 503.5.10.2.2|E 503.5.10.1 – E 503.5.10.1.2| |E 503.5.12.1|E 503.5.12| |E 503.5.12.2|E 503.5.12.1| |E 503.6.5.4|E 503.6.5.4.1|
xxii 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
RELATED PUBLICATIONS AND SERVICES
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Uniform Mechanical Code – 2024 Edition:
The Uniform Mechanical Code contains complete requirements for the installation and maintenance of heating, ventilating, cooking and refrigeration systems.
Uniform Mechanical Code Illustrated Training Manual:
CMC § 5.10.1.2 Medium relevance — show source text
5.10.1.2(2)|Table E 503.5.10(2)| |E 503.5.10.1.2|E 503.5.10| |E 503.5.10.2 – E 503.5.10.2.2|E 503.5.10.1 – E 503.5.10.1.2| |E 503.5.12.1|E 503.5.12| |E 503.5.12.2|E 503.5.12.1| |E 503.6.5.4|E 503.6.5.4.1|
xxii 2025 CALIFORNIA MECHANICAL CODE
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
RELATED PUBLICATIONS AND SERVICES
The Documents Listed are Not by this Reference Adopted by The State of California.
IAPMO provides a variety of other products which are useful for inspectors, building officials, architects, engineers,
manufacturers, contractors, plumbers, and apprentices.
IAPMO Headquarters Directory
4755 East Philadelphia Street, Ontario, California 91761-2816
Publication Order Desk Phone: 800-85-IAPMO
Publication Toll Free Fax: 877-85-CODES
E-mail: iapmo@iapmo.org
Website: www.iapmo.org
Free Code Question: 800-201-0335
Uniform Mechanical Code – 2024 Edition:
The Uniform Mechanical Code contains complete requirements for the installation and maintenance of heating, ventilating, cooking and refrigeration systems.
Uniform Mechanical Code Illustrated Training Manual:
Contains technical diagrams and illustrations that demonstrate the intent and use of the UMC. A great reference for everyone involved in Mechanical HVACR design and installation.
Uniform Mechanical Code Study Guide:
The Study Guide is a complete self-study course for learning the UMC. A big help in getting ready for a certification exam! This book is the perfect complement to the UMC Illustrated Training Manual.
Guide to Important Code Questions to the Uniform Mechanical Code:
An excellent reference for learning and understanding mechanical code changes and identifies code changes between editions. It is a useful tool for preparing code change proposals.
Uniform Plumbing Code – 2024 Edition:
The Uniform Plumbing Code is the most widely adopted plumbing code in the world. The 2024 edition contains complete “turnkey” requirements for the installation and maintenance of plumbing systems, all in one easy to use book.
Uniform Plumbing Code Illustrated Training Manual:
The UPC Illustrated Training Manual is an excellent reference for anyone involved in the plumbing industry. It contains an extensive definitions section and several hundred comprehensive technical diagrams and illustrations. It serves as a textbook, and it also is useful as a valuable tool for explaining the intent and use of the Code.
Uniform Plumbing Code Study Guide:
This book is the perfect complement to the UPC Illustrated Training Manual. Alone, it constitutes a complete self-study course for learning the UPC. It has hundreds of questions, general practice exams, and plumbing math, pipe sizing exercises and fitting identification. A big help in getting you ready for a certification exam!
Guide to Important Code Questions to the Uniform Plumbing Code:
An excellent reference for learning and understanding plumbing code changes and identifies code changes between editions. It is a useful tool for preparing code change proposals.
2025 CALIFORNIA MECHANICAL CODE xxiii
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
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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]
Frequently asked questions
Which specific IIAR documents does the CMC point to for ammonia systems?
The CMC directs ammonia refrigeration systems to IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6, and states they need not comply with Chapter 11. See § 1102.2.
If a system uses CO2, do I follow IIAR or ASHRAE?
You must follow ASHRAE 15 and Chapter 11, and also comply with IIAR CO2 as required by § 1102.1.
Does “not be required to comply with this chapter” mean IIAR replaces all CMC requirements for ammonia?
Yes — for the aspects covered by the referenced IIAR documents the CMC directs designers/operators to IIAR standards for ammonia systems. Always confirm with the AHJ for any local enforcement specifics. See § 1102.2.
Where do I find refrigerant classifications referenced by the chapter?
See Table 1102.3 and the classification language, and ASHRAE 34 where approved by the AHJ (see § 1102.3).
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