CMC · California Mechanical Code
What emergency shutdown and remote control requirements apply to machinery rooms?
If your building has a refrigeration machinery room, the CMC requires a clearly marked break‑glass emergency shutoff placed immediately outside the main machinery‑room entrance that only turns equipment off (compressors, pumps, normally‑closed valves). Ventilation fans must be on a separate circuit with their own on‑only switch outside the door. For flammable refrigerants, detectors must trigger automatic shutdown at Alarm 2 (upper detection limit or 25% of LFL).
Last reviewed: July 6, 2026
What the code requires — 2–4 sentences
Machinery rooms that house refrigerant equipment must have a clearly identified emergency shutoff switch located immediately adjacent to and outside the principal machinery-room entrance that provides off-only control of compressors, refrigerant pumps and normally-closed automatic refrigerant valves (§ 1108.3). Remote shutdown capability of machinery-room mechanical equipment must be provided immediately outside the machinery room door for emergency shutdown, and ventilation fans must be on a separate electrical circuit with an on-only control switch located immediately outside the door (§ 1107.1.10). For flammable refrigerants, the Fire Code requires the same break‑glass style shutoff and also requires automatic shutdown when detector levels reach the specified alarm threshold (§ 608.10.1).
The single most important rule: provide a clearly marked, break‑glass or tamper‑resistant off‑only emergency shutoff immediately outside the principal machinery-room entrance and ensure detectors/alarms will automatically stop equipment at the alarm set point where required.
Requirements in detail
Location and type of the emergency control
- Where: immediately adjacent to and outside the principal refrigeration machinery room entrance — the switch must be accessible from outside the room (§ 1108.3, § 1107.1.10).
- Type: break‑glass type or approved tamper‑resistant cover for the emergency shutoff (§ 1108.3, Fire Code § 608.10.1).
What the switch must do (control function)
- Emergency shutoff must provide off‑only control of: refrigerant compressors, refrigerant pumps, and normally‑closed automatic refrigerant valves located in the machinery room (§ 1108.3, Fire Code § 608.10.1).
- Ventilation fans must have a separate circuit and an on‑only control switch located immediately outside the door (remote control for ventilation) (§ 1107.1.10, Fire Code § 608.10.2).
Automatic activation by detectors
- For refrigerants other than A1 and B1, the required emergency shutoff must be automatically activated by refrigerant Alarm 2 (i.e., the higher alarm level) in accordance with the detector/alarm requirements, so the shutoff can operate without manual activation when the alarm threshold is reached (§ 1108.3).
- The detector activation thresholds used by the CMC / ASHRAE-derived machinery-room requirements are the upper detection limit of the detector or 25 percent of the lower flammable limit (LFL), whichever is lower; when that value is reached the equipment listed must be de‑energized (§ 1106.11.6.2, Fire Code § 608.9.1).
- The detector/alarm table in the CMC sets response times and reset types (Alarm 2 / emergency alarm — manual reset; Alarm 1 / trouble — automatic), which governs when ventilation and shutdown actions occur (see Table 1106.11.10.2) (§ 1106.11.10.2).
Decision‑relevant summary table
| Decision factor | Requirement | Value / action | Code Reference |
|---|---|---|---|
| Emergency shutoff location | Outside principal entrance, immediately adjacent | Switch immediately adjacent to and outside machinery-room entrance | § 1108.3 |
| Switch type | Visible, tamper‑resistant | Break‑glass or approved tamper‑resistant cover | § 1108.3; § 608.10.1 |
| Control function | Compressors/pumps/valves | Off‑only control of compressors, refrigerant pumps, normally‑closed automatic refrigerant valves | § 1108.3; § 608.10.1 |
| Automatic activation | When required | Automatically activated by Alarm 2 for refrigerants other than A1/B1; automatic shutdown at detector upper limit or 25% LFL (whichever lower) | § 1108.3; § 1106.11.6.2; § 608.9.1 |
| Ventilation fans control | Circuit & remote control | Fans on separate electrical circuit; on‑only switch located immediately outside machinery room door | § 1107.1.10; § 608.10.2 |
| Detector response / reset | Alarm levels & timing | Table 1106.11.10.2 sets response times and manual/automatic reset types (Alarm 2 = emergency/manual reset) | § 1106.11.10.2 |
Exceptions & special cases
- Automatic activation does not apply to A1 and B1 refrigerants — for those refrigerants the emergency shutoff is still required as a manual remote control but automatic Alarm‑2 activation is specified for refrigerants other than A1/B1 (§ 1108.3).
- Where flammable refrigerants are used and § 1106 applies, the Fire Code restates the remote‑control and automatic‑shutdown requirements (see § 608.10.1 and § 608.10.2) and ties detector thresholds to LFL percentages — follow both CMC and Fire Code language for flammable refrigerants.
- Group A2 / A3 / B2 / B3 refrigerants impose additional electrical classification requirements (machinery rooms may need Class I, Division 2 electrical compliance) — consult § 1107.1.8 and the Fire Code for electrical location classification.
If a particular requirement or nuance is not explicitly covered in the retrieved CMC text you provided, I have called that out rather than inventing additional requirements.
Common mistakes
- Installing the emergency shutoff switch inside the machinery room instead of immediately outside the principal entrance (violates § 1108.3 / § 1107.1.10).
- Using a combined circuit for ventilation fans rather than a separate electrical circuit (ventilation must be separable and have its own outside switch). § 1107.1.10.
- Making the equipment shutoff an on/off multiposition switch instead of an off‑only emergency shutdown for compressors/pumps/valves as required by § 1108.3 and § 608.10.1.
- Failing to configure detectors and Alarm 2 setpoints so that automatic shutdown occurs at the proper threshold (upper detection limit or 25% of LFL) — check Table 1106.11.10.2 and § 1106.11.6.2 for alarm logic.
- Not using a break‑glass or tamper‑resistant cover for exterior emergency switches — the code requires visible, approved protection (§ 1108.3, § 608.10.1).
Worked example — concrete scenario
Scenario: A supermarket installs a refrigeration machinery room with a refrigerant that is flammable (so Fire Code detector rules apply). The project team must comply as follows:
- Install a clearly labeled break‑glass emergency shutoff immediately adjacent to the principal machinery‑room door that provides off‑only control of the room’s compressors, pumps and normally‑closed automatic refrigerant valves, per § 1108.3 and § 608.10.1.
- Mount an on‑only switch for the machinery‑room exhaust fans on a separate electrical circuit, and place that switch immediately outside the door per § 1107.1.10 and § 608.10.2.
- Configure the refrigerant detectors so Alarm 2 will activate at the detector’s upper detection limit or 25% of the LFL, whichever is lower; program Alarm 2 to automatically shut off compressors/pumps/valves (automatic activation required for refrigerants other than A1/B1) per § 1108.3 and the detector/ventilation requirements in § 1106.11.6.2 and Table 1106.11.10.2.
Sequence when a leak occurs: detector reaches Alarm 2 threshold (25% LFL or upper limit) → detector annunciates and transmits alarm → system automatically de‑energizes compressors/pumps/normally‑closed valves (and records alarm) → break‑glass switch remains available outside for manual shutoff or to reset per the required reset type (Alarm 2 emergency alarms generally require manual reset) (§ 1106.11.10.2, § 1108.3, § 608.10.1).
Related provisions
- § 1106.11.6.2 — Equipment automatically de‑energized by detector action (list of equipment).
- § 1106.11.10.2 — Detector set points, response times, alarm/reset types (Table 1106.11.10.2).
- § 1106.2.5 — Detector/alarm requirements referenced for Alarm 2 activation.
- § 1107.1.7.2 — Detector action to de‑energize equipment at alarm levels.
- § 1107.1.8 — Electrical classification where A2, A3, B2, B3 refrigerants are used.
- § 608.9.1 (Fire Code) — Detector alarm levels (upper detection limit vs 25% LFL) and required alarm annunciation.
- § 608.10.1 (Fire Code) — Refrigeration system emergency shutoff wording consistent with § 1108.3.
- § 608.10.2 (Fire Code) — Ventilation fan on‑only control requirement.
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 1107.1.10 High relevance — show source text
1107.1.10 Remote Control. Remote control of the
mechanical equipment in the refrigeration machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door.
1108.0 Refrigeration Machinery Room Equipment and Controls.
1108.1 General. Equipment, piping, ducts, vents, or similar devices that are not essential for the refrigeration process, maintenance of the equipment, or for the illumination, ventilation, or fire protection of the room shall not be placed in or pass through a refrigeration machinery room.
1108.2 Electrical. Electrical equipment and installations shall comply with California Electrical Code . The refrigeration machinery room shall not be classified as a hazardous location except as provided in Section 1107.1.7 or Section 1107.1.8.
1108.3 Emergency Shutoff. A clearly identified emergency shutoff switch of the break-glass type or with an approved tamper-resistant cover shall be provided immediately adjacent to and outside of the principal refrigeration machinery room entrance. The switch shall provide off-only control of refrigerant compressors, refrigerant pumps, and normally-closed automatic refrigerant valves located in the machinery room. For other than A1 and B1 refrigerants, emergency shutoff shall be automatically activated by refrigerant Alarm 2 in accordance with Section 1106.2.5.
1108.4 Installation, Maintenance, and Testing. Detection and alarm systems in accordance with Section 1106.2.5 shall be installed, maintained, and tested in accordance with the California Fire Code and with the equipment manufac- turer’s specification . 1108.5 Emergency Pressure Control System. Where required by the fire code, an emergency pressure control system shall be installed in accordance with applicable fire code requirements.
1109.0 Refrigeration Piping, Containers, and Valves.
1109.1 Materials. Materials used in the construction and installation of refrigerating systems shall be suitable for conveying the refrigerant used. Materials shall not be used that will deteriorate because of the refrigerant, the lubricant, or their combination in the presence of air or moisture to a degree that poses a safety hazard. [ASHRAE 15:9.1.1] Refrigerant piping shall be metallic. Materials for refrigerant piping, tubing, and fittings shall comply with the applicable standards in Table 1109.1.
2025 CALIFORNIA MECHANICAL CODE 237
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REFRIGERATION
For SI Units: 1 pound = 0.453 kg, 1 cubic foot per minute = 0.47194 L/s, 1 pound-force per square inch = 6.8947 kPa
FIGURE 1106.11.11.4
LEVEL 2 VENTILATION RATE FOR CLASS 2L REFRIGERANTS
[ASHRAE 15: FIGURE 8-1]
238 2025 CALIFORNIA MECHANICAL CODE
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REFRIGERATION
CMC § 1107.1.7.1 High relevance — show source text
1107.1.7.1 Mechanical Ventilation. The mechanical ventilation system in the machinery room is run continuously in accordance with Section 1106.11.6.1 and failure of the mechanical ventilation system actuates an alarm, or the mechanical ventilation system in the machinery room is activated by one or more refrigerant detectors, in accordance with the requirements of Section 1106.11.11.
1107.1.7.2 Refrigeration Detectors. For the refrigerant detection required in Section 1106.2.5, detection of refrigerant concentration that exceeds 25 percent of the LFL or the upper detection limit of the refrigerant detector, whichever is lower, shall automatically de-energize the following equipment in the machinery room:
(1) refrigerant compressors
(2) refrigerant pumps
(3) normally-closed automatic refrigerant valves
1107.1.7.3 Machinery Rooms. The machinery room shall comply with Section 1106.11. 1107.1.8 Group A2, A3, B2, or B3 Refrigerants. Where any refrigerant of Groups A2, A3, B2, or B3 are used, the machinery room shall comply with Class 1, Division 2, of of the California Electrical Code .
1107.1.9 Refrigeration Systems. As part of the mechanical ventilation system in accordance with Section 1106.2.8, refrigeration systems that contain more
than 110 pounds (50 kg) of any Group A2L, A2, A3, B2L, B2, or B3, refrigerant shall have not less than one exhaust air inlet located adjacent to each system not more than 9 feet (3 m) away.
1107.1.10 Remote Control. Remote control of the
mechanical equipment in the refrigeration machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door.
1108.0 Refrigeration Machinery Room Equipment and Controls.
1108.1 General. Equipment, piping, ducts, vents, or similar devices that are not essential for the refrigeration process, maintenance of the equipment, or for the illumination, ventilation, or fire protection of the room shall not be placed in or pass through a refrigeration machinery room.
1108.2 Electrical. Electrical equipment and installations shall comply with California Electrical Code . The refrigeration machinery room shall not be classified as a hazardous location except as provided in Section 1107.1.7 or Section 1107.1.8.
1108.3 Emergency Shutoff. A clearly identified emergency shutoff switch of the break-glass type or with an approved tamper-resistant cover shall be provided immediately adjacent to and outside of the principal refrigeration machinery room entrance. The switch shall provide off-only control of refrigerant compressors, refrigerant pumps, and normally-closed automatic refrigerant valves located in the machinery room. For other than A1 and B1 refrigerants, emergency shutoff shall be automatically activated by refrigerant Alarm 2 in accordance with Section 1106.2.5.
CMC § 608.9.1 High relevance — show source text
608.9.1 Refrigerants other than ammonia. A detector, or a sampling tube that draws air to a detector, shall be provided at an approved location where refrigerant from a leak is expected to accumulate. The system shall be designed to initiate audible and visible alarms inside of and outside each entrance to the refrigerating machinery room and transmit a signal to an approved location where the concentration of refrigerant detected exceeds the lesser of the following:
- The corresponding TLV-TWA values shown in the California Mechanical Code for the refrigerant classification.
- Twenty-five percent of the lower flammable limit (LFL).
Detection of a refrigerant concentration exceeding the upper detection limit or 25 percent of the lower flammable limit (LFL), whichever is lower, shall stop refrigerant equipment in the machinery room in accordance with Section 608.10.1.
608.10 Remote controls. Where flammable refrigerants are used and compliance with Section 1106 of the California Mechanical Code is required, remote control of the mechanical equipment and appliances located in the machinery room as required by Sections 608.10.1 and 608.10.2 shall be provided at an approved location immediately outside the machinery room and adjacent to its principal entrance.
608.10.1 Refrigeration system emergency shutoff. A clearly identified switch of the break-glass type or with an approved tamperresistant cover shall provide off-only control of refrigerant compressors, refrigerant pumps and normally closed automatic refrigerant valves located in the machinery room. Additionally, this equipment shall be automatically shut off when the refrigerant vapor concentration in the machinery room exceeds the vapor detector’s upper detection limit or 25 percent of the LEL, whichever is lower.
608.10.2 Ventilation system. A clearly identified switch of the break-glass type or with an approved tamper-resistant cover shall provide on-only control of the machinery room ventilation fans.
608.11 Emergency pressure control system. Permanently installed refrigeration systems in machinery rooms containing more than 6.6 pounds (3 kg) of flammable, toxic or highly toxic refrigerant or ammonia shall be provided with an emergency pressure control system in accordance with Sections 608.11.1 and 608.11.2.
608.11.1 Automatic crossover valves. Each high- and intermediate-pressure zone in a refrigeration system shall be provided with a single automatic valve providing a crossover connection to a lower pressure zone. Automatic crossover valves shall comply with Sections 608.11.1.1 through 608.11.1.3.
608.11.1.1 Overpressure limit set point. Automatic crossover valves shall be arranged to automatically relieve excess system pressure to a lower pressure zone if the pressure in a high- or intermediate-pressure zone rises to within 90 percent of the set point for emergency pressure relief devices.
608.11.1.2 Manual operation. Where required by the fire code official, automatic crossover valves shall be capable of manual operation.
608.11.1.3 System design pressure. Refrigeration system zones that are connected to a higher pressure zone by an automatic crossover valve shall be designed to safely contain the maximum pressure that can be achieved by interconnection of the two zones.
608.11.2 Automatic emergency stop. An automatic emergency stop feature shall be provided in accordance with Sections 608.11.2.1 and 608.11.2.2.
CMC § 3108F.3 High relevance — show source text
VT = VSL + VSH + VFL + VFH = Total Volume (stored and flowing)
* Quantities are based on maximum flow rate, including simultaneous transfers._|3108F.3 Fire prevention.
3108F.3.1 Ignition source control.
3108F.3.1.1 Protection from ignition by static electricity, lightning or stray currents shall be in accordance with API RP 2003
8.4.
3108F.3.1.2 Requirements to prevent electrical arcing shall be in conformity with 2 CCR 2341 [8.3] (N/E).
3108F.3.1.3 Multi-berth terminal piers shall be constructed so as to provide a minimum of 100 ft between adjacent manifolds (N).
3108F.3.2 Emergency shutdown (ESD) systems. Emergency shutdown systems are essential to oil spill and fire prevention. These systems may include, but are not limited to, ESD valves, shore isolation valves (SIVs), automatic pump shutdown, controls, actuators and alarms. The ESD systems shall conform to 2 CCR 2380 [8.3] and 33 CFR 154.550 [8.5], and provide: 1. Remote actuation stations strategically located, so that ESD valve(s) may be shut within required times (N). 2. Multiple actuation stations installed at strategic locations, so that one such station is located more than 100 ft from areas classified as Class I, Group D, Division 1 or 2 per the California Electrical Code [8.6]. Actuation stations shall be wired in paral- lel to achieve redundancy and arranged so that fire damage to one station will not disable the ESD system (N). 3. Communications or control circuits to synchronize simultaneous closure of the shore isolation valves (SIVs) with the shut- down of loading pumps (N). 4. A manual reset to restore the ESD system to an operational state after each initiation (N). 5. An alarm to indicate failure of the primary power source (N). 6. A secondary (emergency) power source (N). 7. Periodic testing of the system (N/E). 8. Fire proofing of motors and control-cables that are installed in areas classified as Class I, Group D, Division 1 or 2 per the California Electrical Code [8.6]. Fire proofing shall, at a minimum, comply with the recommendations in Section 6 of API RP 2218 [8.7] (N).
3108F.3.2.1 Emergency shutdown (ESD) valves. ESD valves shall conform to the requirements in Section 3109F.5, as applicable, and the following: 1. Be located near the dock manifold connection or loading arm (N/E). 2. Have “Local” and “Remote” actuation capabilities (N).
CMC § 1106.2.5 Medium relevance — show source text
(1) Combustion air shall be ducted from outside the machinery room and sealed in such a manner as to prevent refrigerant leakage from entering the combustion chamber.
(2) A refrigerant detector, that is in accordance with Section 1106.2.5, shall be installed to automatically shut down the combustion process in the event of refrigerant leak age.
Exception: Machinery rooms where carbon dioxide (R-744) or water (R-718) is the refrigerant.
1106.6 Ventilation Intake. Makeup air intakes to replace the exhaust air shall be provided to the refrigeration machinery room directly from outside the building. Intakes shall be located as required by other sections of the code and fitted with backdraft dampers or other approved flow-control means to prevent reverse flow. Distribution of makeup air shall be arranged to provide thorough mixing within the refrigeration machinery room to prevent short circuiting of the makeup air directly to the exhaust.
234 2025 CALIFORNIA MECHANICAL CODE
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REFRIGERATION
1106.11.6.1 Mechanical Ventilation. The machinery room shall have a mechanical ventilation system in accordance with Section 1106.11.11. The mechanical ventilation system shall:
(1) Run continuously, and failure of the mechanical ventilation system actuates an alarm, or
(2) Be activated by one or more refrigerant detectors, conforming to requirements of Section 1106.11.8. [ASHRAE 15:8.13.6.1] 1106.11.6.2 Detection System. Detection of refrigerant concentration that exceeds 25 percent of the LFL or the upper detection limit of the refrigerant detector, whichever is lower, shall automatically de-energize the following equipment in the machin ery room:
(1) Refrigerant compressors
(2) Refrigerant pumps
(3) Normally closed automatic refrigerant valves
(4) Other unclassified electrical sources of ignition with apparent power rating greater than 1 kVA, where the apparent power is the product of the circuit voltage and current rating. [ASHRAE 15:8.13.6.2] 1106.11.7 Mechanical Equipment Control. Remote control of the mechanical equipment in the refrigerating machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door. [ASHRAE 15:8.13.7] 1106.11.8 Refrigerant Detectors. Each refrigerating machinery room in accordance with Section 1106.11 shall contain one or more refrigerant detectors in accordance with Section 1106.11.9. The detector(s) sensing element shall be located in areas where refrigerant from a leak will concentrate, with one or more set points that activate responses in accordance with Section 1106.11.10 for alarms and Section 1106.11.11 for mechanical ventilation. Multiport-type devices shall be prohibited. {ASHRAE 15:8.13.8} 1106.11.9 Refrigerant Detectors Requirements. Refrigerant detectors required by Section 1106.11 shall meet all of the following conditions:
CMC § 8.13.6.2 Medium relevance — show source text
(1) Refrigerant compressors
(2) Refrigerant pumps
(3) Normally closed automatic refrigerant valves
(4) Other unclassified electrical sources of ignition with apparent power rating greater than 1 kVA, where the apparent power is the product of the circuit voltage and current rating. [ASHRAE 15:8.13.6.2] 1106.11.7 Mechanical Equipment Control. Remote control of the mechanical equipment in the refrigerating machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door. [ASHRAE 15:8.13.7] 1106.11.8 Refrigerant Detectors. Each refrigerating machinery room in accordance with Section 1106.11 shall contain one or more refrigerant detectors in accordance with Section 1106.11.9. The detector(s) sensing element shall be located in areas where refrigerant from a leak will concentrate, with one or more set points that activate responses in accordance with Section 1106.11.10 for alarms and Section 1106.11.11 for mechanical ventilation. Multiport-type devices shall be prohibited. {ASHRAE 15:8.13.8} 1106.11.9 Refrigerant Detectors Requirements. Refrigerant detectors required by Section 1106.11 shall meet all of the following conditions:
(1) A refrigerant detector shall be capable of detecting each of the specific refrigerant designations in the machinery room.
(2) The refrigerant detector shall activate responses within a time not to exceed a limit specified in Section 1106.11.10 and Section 1106.11.11 after exposure to refrigerant concentration exceeding a limit value specified in Section 1106.11.10 and Section 1106.11.11.
(3) The refrigerant detector shall have a set point not greater than the applicable Occupational Exposure Limit (OEL) value in accordance with Table 1102.3. The applicable OEL value shall be the lowest OEL value for any refrigerant designation in the machinery room. For refrigerants that do not have an OEL value in Table 1102.3, use a value determined in accordance with the OEL as defined by ASHRAE 34 where approved by the Authority Having Jurisdiction.
(4) The refrigerant detector shall have a set point not more than the applicable Refrigerant Concentration Limit (RCL) value in accordance with Table 1102.3. The applicable RCL value shall be the lowest RCL value for any refrigerant designation in the machinery room. For refrigerants that do not have a RCL value in Table 1102.3, use a value determined in accordance with the RCL as defined by ASHRAE 34 where approved by the Authority Having Jurisdiction.
(5) The refrigerant detector shall provide a means for automatic self-testing and shall be in accordance with Section 1106.11.10.4. The refrigerant detector shall be tested during installation and annually thereafter in accordance with the fire code, or at an interval not exceeding the manufacturer’s installation instructions, whichever is less. Testing shall verify compliance with the alarm set points and response times per Section 1106.11.10 and Section 1106.11.11. [ASHRAE 15:8.13.9]
CMC § 608.7 Medium relevance — show source text
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.
6-10 2025 CALIFORNIA FIRE CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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.
- 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.
608.9.1 Refrigerants other than ammonia. A detector, or a sampling tube that draws air to a detector, shall be provided at an approved location where refrigerant from a leak is expected to accumulate. The system shall be designed to initiate audible and visible alarms inside of and outside each entrance to the refrigerating machinery room and transmit a signal to an approved location where the concentration of refrigerant detected exceeds the lesser of the following:
- The corresponding TLV-TWA values shown in the California Mechanical Code for the refrigerant classification.
- Twenty-five percent of the lower flammable limit (LFL).
Detection of a refrigerant concentration exceeding the upper detection limit or 25 percent of the lower flammable limit (LFL), whichever is lower, shall stop refrigerant equipment in the machinery room in accordance with Section 608.10.1.
608.10 Remote controls. Where flammable refrigerants are used and compliance with Section 1106 of the California Mechanical Code is required, remote control of the mechanical equipment and appliances located in the machinery room as required by Sections 608.10.1 and 608.10.2 shall be provided at an approved location immediately outside the machinery room and adjacent to its principal entrance.
608.10.1 Refrigeration system emergency shutoff. A clearly identified switch of the break-glass type or with an approved tamperresistant cover shall provide off-only control of refrigerant compressors, refrigerant pumps and normally closed automatic refrigerant valves located in the machinery room. Additionally, this equipment shall be automatically shut off when the refrigerant vapor concentration in the machinery room exceeds the vapor detector’s upper detection limit or 25 percent of the LEL, whichever is lower.
CMC § 8.13.6 Medium relevance — show source text
[ASHRAE 15:8.13.6]
»
(1) Operated, where occupied, to supply not less than 0.5 CFM/ft [2] [2.54 L/(s•m [2] )] of machinery room area or 20 cubic feet per minute (9.44 L/s) per person.
(2) Operable, where occupied at a volume required to not exceed the higher of a temperature rise of 18°F (10°C) above inlet air temperature or a maximum temperature of 122°F (50°C).
1106.4 Natural Ventilation. When a refrigerating system is located outdoors more than 20 feet (6096 mm) from building openings and is enclosed by a penthouse, lean-to, or other open structure, natural or mechanical ventilation shall be provided. The requirements for such natural ventilation shall be in accordance with the following:
(1) The free-aperture cross section for the ventilation of a machinery room shall be not less than as determined in accordance with Equation 1106.4.
F = √ G (Equation 1106.4)
Where:
F = The free opening area, ft [2] (m [2] ).
G = The mass of refrigerant in the largest system, any part of which is located in the machinery room, pounds.
For SI units: 1 square foot = 0.0929 m [2], 1 pound = 0.453 kg
(2) Locations of the gravity ventilation openings shall be based on the relative density of the refrigerant to air.
[ASHRAE 15:8.14]
1106.5 Combustion Air. No open flames that use combustion air from the machinery room shall be installed where refrigerant is used. Combustion equipment shall not be installed in the same machinery room with refrigerant-containing equipment except under one of the following conditions:
(1) Combustion air shall be ducted from outside the machinery room and sealed in such a manner as to prevent refrigerant leakage from entering the combustion chamber.
(2) A refrigerant detector, that is in accordance with Section 1106.2.5, shall be installed to automatically shut down the combustion process in the event of refrigerant leak age.
Exception: Machinery rooms where carbon dioxide (R-744) or water (R-718) is the refrigerant.
1106.6 Ventilation Intake. Makeup air intakes to replace the exhaust air shall be provided to the refrigeration machinery room directly from outside the building. Intakes shall be located as required by other sections of the code and fitted with backdraft dampers or other approved flow-control means to prevent reverse flow. Distribution of makeup air shall be arranged to provide thorough mixing within the refrigeration machinery room to prevent short circuiting of the makeup air directly to the exhaust.
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), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
REFRIGERATION
1106.11.6.1 Mechanical Ventilation. The machinery room shall have a mechanical ventilation system in accordance with Section 1106.11.11. The mechanical ventilation system shall:
(1) Run continuously, and failure of the mechanical ventilation system actuates an alarm, or
CMC § 8.6 Medium relevance — show source text
Actuation stations shall be wired in paral-_ lel to achieve redundancy and arranged so that fire damage to one station will not disable the ESD system (N). 3. Communications or control circuits to synchronize simultaneous closure of the shore isolation valves (SIVs) with the shut- down of loading pumps (N). 4. A manual reset to restore the ESD system to an operational state after each initiation (N). 5. An alarm to indicate failure of the primary power source (N). 6. A secondary (emergency) power source (N). 7. Periodic testing of the system (N/E). 8. Fire proofing of motors and control-cables that are installed in areas classified as Class I, Group D, Division 1 or 2 per the California Electrical Code [8.6]. Fire proofing shall, at a minimum, comply with the recommendations in Section 6 of API RP 2218 [8.7] (N).
3108F.3.2.1 Emergency shutdown (ESD) valves. ESD valves shall conform to the requirements in Section 3109F.5, as applicable, and the following: 1. Be located near the dock manifold connection or loading arm (N/E). 2. Have “Local” and “Remote” actuation capabilities (N).
3108F.3.2.2 Shore isolation valves (SIVs). Shore isolation valve(s) shall conform to the requirements in Section 3109F.5, as appli- cable, and the following: 1. Be located onshore for each cargo pipeline. All SIVs shall be clustered together, for easy access (N). 2. Be clearly identified together with associated pipeline (N/E). 3. Have adequate lighting (N/E). 4. Be provided with communications or control circuits to synchronize simultaneous closure of the ESD system with the shutdown of loading pumps (N).
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MARINE OIL TERMINALS
5. Have a manual reset to restore the SIV system to an operational state after each shut down event (N). 6. Be provided with thermal expansion relief to accommodate expansion of the liquid when closed. Thermal relief piping shall be properly sized and routed around the SIV, into the downstream segment of the pipeline or into other contain- ment (N/E). 7. SIVs installed in pipelines carrying H C liquids, or at a MOT with a spill classification “Medium” or “High” (see Table 31F-1- 1), shall be equipped with “Local” and “Remote” actuation capabilities. Local control SIVs may be motorized and/or operated manually (N).
3108F.4 Automated fire detection system. An MOT shall have a permanently installed automated fire detection or sensing system (N).
Fire detection systems shall be tested and maintained per the manufacturer or the local enforcing agency requirements. Specifica- tions shall be retained. The latest testing and maintenance records shall be readily accessible to the Division (N/E).
CMC § 0.25 Medium relevance — show source text
RC.I|0.25 ×V + 0.63|0.25 ×V + 0.63| |Commercial ice-
cream freezers|Remote (RC)|Horizontal Closed
Solid (HCS)|Horizontal Closed
Solid (HCS)|Horizontal Closed
Solid (HCS)|HCS.RC.I|0.25 ×V + 0.63|0.25 ×V + 0.63| |Commercial ice-
cream freezers|Remote (RC)|Service Over
Counter (SOC)|Service Over
Counter (SOC)|Service Over
Counter (SOC)|SOC.RC.I|1.09 ×TDA + 0.26|1.09 ×TDA + 0.26| |Commercial ice-
cream freezers|Self-contained
(SC)|Vertical Open
(VOP)|Vertical Open
(VOP)|Vertical Open
(VOP)|VOP.SC.I|5.40 ×TDA + 15.02|AHRI 1200| |Commercial ice-
cream freezers|Self-contained
(SC)|Semivertical Open
(SVO)|Semivertical Open
(SVO)|Semivertical Open
(SVO)|SVO.SC.I|5.41 ×TDA + 14.63|5.41 ×TDA + 14.63| |Commercial ice-
cream freezers|Self-contained
(SC)|Horizontal Open
(HZO)|Horizontal Open
(HZO)|Horizontal Open
(HZO)|HZO.SC.I|2.42 ×TDA + 9.00|2.42 ×TDA + 9.00| |Commercial ice-
cream freezers|Self-contained
(SC)|Vertical Closed
Transparent (VCT)|Vertical Closed
Transparent (VCT)|Vertical Closed
Transparent (VCT)|VCT.SC.I|0.62 ×TDA + 3.29|0.62 ×TDA + 3.29| |Commercial ice-
cream freezers|Self-contained
(SC)|Horizontal Closed
Transparent (HCT)|Horizontal Closed
Transparent (HCT)|Horizontal Closed
Transparent (HCT)|HCT.SC.I|0.56 ×TDA + 0.43|0.56 ×TDA + 0.43| |Commercial ice-
cream freezers|Self-contained
(SC)|Vertical Closed
Solid (VCS)|Vertical Closed
Solid (VCS)|Vertical Closed
Solid (VCS)|VCS.SC.I|0.34 ×V + 0.88|0.34 ×V + 0.88| |Commercial ice-
cream freezers|Self-contained
(SC)|Horizontal Closed
Solid (HCS)|Horizontal Closed
Solid (HCS)|Horizontal Closed
Solid (HCS)|HCS.SC.I|0.34 ×V + 0.88|0.34 ×V + 0.88| |Commercial ice-
cream freezers|Self-contained
(SC)|Service Over
Counter (SOC)|Service Over
Counter (SOC)|Service Over
Counter (SOC)|SOC.SC.I|1.53 ×TDA +0.36|1.53 ×TDA +0.36|For SI units: °C=(°F-32)/1.8
CMC § 3004.2 Medium relevance — show source text
3004.2 Escalators and moving walks. Escalators and moving walks shall be constructed of approved noncombustible and fireretardant materials. This requirement shall not apply to electrical equipment, wiring, wheels, handrails and the use of [1] / 28 -inch (0.9 mm) wood veneers on balustrades backed up with noncombustible materials.
3004.2.1 Enclosure. Escalator floor openings shall be enclosed with shaft enclosures complying with Section 713.
3004.2.2 Escalators. Where provided in below-grade transportation stations, escalators shall have a clear width of not less than 32 inches (815 mm).
3004.3 Conveyors. Conveyors and conveying systems shall comply with ASME B20.1.
3004.3.1 Enclosure. Conveyors and related equipment connecting successive floors or levels shall be enclosed with shaft enclosures complying with Section 713.
3004.3.2 Conveyor safeties. Power-operated conveyors, belts and other material-moving devices shall be equipped with automatic limit switches that will shut off the power in an emergency and automatically stop all operation of the device.
3004.4 Personnel and material hoists. Personnel and material hoists shall be designed utilizing an approved method that accounts for the conditions imposed during the intended operation of the hoist device. The design shall include, but is not limited to, anticipated loads, structural stability, impact, vibration, stresses and seismic restraint. The design shall account for the construction, installation, operation and inspection of the hoist tower, car, machinery and control equipment, guide members and hoisting mechanism. Additionally, the design of personnel hoists shall include provisions for field testing and maintenance that will demonstrate that the hoist device functions in accordance with the design. Field tests shall be conducted upon the completion of an installation or following a major alteration of a personnel hoist.
SECTION 3005—MACHINE ROOMS
3005.1 Access. A permanent and approved means of access shall be provided to elevator machine rooms, control rooms, control spaces and machinery spaces.
3005.2 Temperature and humidity control. Elevator machine rooms, machinery spaces that contain the driving machine, and control rooms or spaces that contain the operation or motion controller for elevator operation shall be provided with an independent ventilation or air-conditioning system to protect against the overheating of the electrical equipment. The system shall maintain the temperature and humidity be capable of maintaining temperatures within the range established by the manufacturer of the elevator equipment.
3005.3 Pressurization. The elevator machine room, control rooms or control space with openings into a pressurized elevator hoistway shall be pressurized upon activation of a heat or smoke detector located in the elevator machine room, control room or control space.
3005.4 Machine rooms, control rooms, machinery spaces, and control spaces. The following rooms and spaces shall be enclosed with fire barriers constructed in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 711, or both:
Machine rooms.
Control rooms.
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ELEVATORS AND CONVEYING SYSTEMS
- Control spaces.
- Machinery spaces outside of the hoistway enclosure.
CMC § 2.79 Medium relevance — show source text
I|2.79 ×TDA + 8.70|AHRI 1200| |Commercial ice-
cream freezers|Remote (RC)|Semivertical Open
(SVO)|Semivertical Open
(SVO)|Semivertical Open
(SVO)|SVO.RC.I|2.79 ×TDA + 8.70|2.79 ×TDA + 8.70| |Commercial ice-
cream freezers|Remote (RC)|Horizontal Open
(HZO)|Horizontal Open
(HZO)|Horizontal Open
(HZO)|HZO.RC.I|0.70 ×TDA + 8.74|0.70 ×TDA + 8.74| |Commercial ice-
cream freezers|Remote (RC)|Vertical Closed
Transparent (VCT)|Vertical Closed
Transparent (VCT)|Vertical Closed
Transparent (VCT)|VCT.RC.I|0.58 ×TDA + 3.05|0.58 ×TDA + 3.05| |Commercial ice-
cream freezers|Remote (RC)|Horizontal Closed
Transparent (HCT)|Horizontal Closed
Transparent (HCT)|Horizontal Closed
Transparent (HCT)|HCT.RC.I|0.40 ×TDA + 0.31|0.40 ×TDA + 0.31| |Commercial ice-
cream freezers|Remote (RC)|Vertical Closed
Solid (VCS)|Vertical Closed
Solid (VCS)|Vertical Closed
Solid (VCS)|VCS.RC.I|0.25 ×V + 0.63|0.25 ×V + 0.63| |Commercial ice-
cream freezers|Remote (RC)|Horizontal Closed
Solid (HCS)|Horizontal Closed
Solid (HCS)|Horizontal Closed
Solid (HCS)|HCS.RC.I|0.25 ×V + 0.63|0.25 ×V + 0.63| |Commercial ice-
cream freezers|Remote (RC)|Service Over
Counter (SOC)|Service Over
Counter (SOC)|Service Over
Counter (SOC)|SOC.RC.I|1.09 ×TDA + 0.26|1.09 ×TDA + 0.26| |Commercial ice-
cream freezers|Self-contained
(SC)|Vertical Open
(VOP)|Vertical Open
(VOP)|Vertical Open
(VOP)|VOP.SC.I|5.40 ×TDA + 15.02|AHRI 1200| |Commercial ice-
cream freezers|Self-contained
(SC)|Semivertical Open
(SVO)|Semivertical Open
(SVO)|Semivertical Open
(SVO)|SVO.SC.I|5.41 ×TDA + 14.63|5.41 ×TDA + 14.63| |Commercial ice-
cream freezers|Self-contained
(SC)|Horizontal Open
(HZO)|Horizontal Open
(HZO)|Horizontal Open
(HZO)|HZO.SC.I|2.42 ×TDA + 9.00|2.42 ×TDA + 9.
Frequently asked questions
Who must provide the emergency shutoff switch?
The design/owner of any refrigeration machinery room required by the CMC must provide it. The switch must be installed immediately outside the principal entrance as required by § 1108.3.
Does the switch need to automatically shut equipment off on detector alarm?
Yes — for refrigerants other than A1 and B1, Alarm 2 must automatically activate the emergency shutoff per § 1108.3; Fire Code § 608.10.1 echoes this for flammable refrigerants and ties it to detector thresholds.
What exactly must be turned off by the emergency shutoff?
The off‑only switch must de‑energize refrigerant compressors, refrigerant pumps, and normally‑closed automatic refrigerant valves located in the machinery room, per § 1108.3.
Can the ventilation fans be controlled from the same switch as the compressors?
No — ventilation fans must be on a separate electrical circuit and have an on‑only control switch located immediately outside the machinery room door per § 1107.1.10 and Fire Code § 608.10.2.
How do detector thresholds affect shutdown?
Detectors are required to stop equipment when refrigerant concentration exceeds the upper detection limit or 25% of the LFL, whichever is lower; the detector/ alarm table sets response times and reset types that determine timing of ventilation and shutdown actions (§ 1106.11.6.2, § 1106.11.10.2, Fire Code § 608.9.1).
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