CFC · California Fire Code

What are the rules for ESS cabinets, walk-in units and equipment enclosures?

If your business installs ESS in occupied areas, the California Fire Code requires them to be in **locked noncombustible cabinets located within 10 feet** of the equipment they serve, with approved signage and no nearby combustible storage; **walk‑in units** containing ESS are for service access only, and **explosion control** must be provided where the ESS technology or Table 1207.6 requires it.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

Energy Storage Systems (ESS) installed in occupied work centers must be housed in locked noncombustible cabinets or other enclosures, kept close to the equipment they serve, and marked with approved signage per § 1207.4.10. Walk‑in units that contain ESS are restricted to inspection, maintenance and repair only and may not be used for other occupancy purposes per § 1207.4.12. Where required by the technology or Table 1207.6, explosion control (Section 911) must be provided for rooms, areas, ESS cabinets or ESS walk‑in units per § 1207.6.3.

The single most important plain‑English rule: ESS cabinets in occupied work areas must be locked, noncombustible enclosures located close to the equipment they support; walk‑in units with ESS are for service access only; and explosion control is required where the code or technology dictates.

Requirements in detail

ESS cabinets in occupied work centers (what the inspector checks)

  • Cabinets must be locked and made of noncombustible material. § 1207.4.10
  • Cabinets must be located within 10 feet (3048 mm) of the equipment they support. § 1207.4.10
  • Cabinets must carry the approved signage required for ESS (see § 1207.4.8). § 1207.4.10
  • Combustible materials must not be stored in ESS rooms/areas; in occupied work centers, combustible storage must be at least 3 feet (914 mm) from ESS cabinets. § 1207.4.6

Walk‑in units (use, access and sizing)

  • Walk‑in units shall be entered only for inspection, maintenance and repair of ESS and ancillary equipment; they are not permitted to be occupied for other purposes. § 1207.4.12
  • For outdoor walk‑in units, the code establishes a maximum outdoor enclosure size beyond which the installation is treated as an indoor ESS location: 53 ft × 8 ft × 9.5 ft (16 154 mm × 2438 mm × 2896 mm). Units larger than this are treated as indoor installations and must follow indoor separation and fire‑resistance rules. § 1207.5.6

Explosion control and enclosures (technology‑triggered requirements)

  • Where Table 1207.6 or other provisions require it, explosion control complying with Section 911 must be provided for rooms, areas, ESS cabinets or ESS walk‑in units containing electrochemical ESS. § 1207.6.3
  • The code also lists specific exceptions (see Exceptions & special cases below) allowing the fire code official to waive explosion control based on large‑scale testing or other documentation. § 1207.6.3

Structural support and seismic references (installation/structural)

  • Stationary ESS must comply with the seismic design requirements in Chapter 16 of the California Building Code and must not exceed the building floor loading limits. § 1207.4.4
  • Construction documents for ESS must include the support arrangement associated with the installation, including any required seismic restraint, so the fire code official can evaluate structural/support measures. § 1207.1.5

Decision‑relevant dimensions / values (quick reference)

Item Required value / action Code Reference
Cabinets — enclosure material Noncombustible and locked § 1207.4.10
Cabinets — distance to supported equipment Within 10 feet (3048 mm) § 1207.4.10
Combustible storage near cabinets Keep combustible materials ≥ 3 feet (914 mm) away in occupied work centers § 1207.4.6
Walk‑in unit permitted use Enter only for inspection, maintenance, repair; no other occupancy § 1207.4.12
Max outdoor walk‑in unit size 53 ft × 8 ft × 9.5 ft (outdoor) — larger = indoor rules § 1207.5.6
Explosion control Required where Table 1207.6 or other provisions indicate — must comply with Section 911 § 1207.6.3
Seismic design Chapter 16, CBC — ESS must meet seismic design and floor loading limits § 1207.4.4

Exceptions & special cases

  • The fire code official may waive explosion control where large‑scale fire testing (UL 9540A) demonstrates no flammable gas liberation or where documentation demonstrates that gas concentrations will not exceed 25% of LFL under fault conditions. § 1207.6.3
  • Explosion control is not required for certain lead‑acid and nickel‑cadmium systems under limited voltages and specific utility/telecom situations described in the exceptions to § 1207.6.3. § 1207.6.3
  • Outdoor walk‑in units that remain under the maximum outdoor size are treated differently from indoor installations; if they exceed 53 ft × 8 ft × 9.5 ft, they must comply with the indoor ESS rules (fire‑resistance separations, suppression, etc.). § 1207.5.6

If a proposed alternative (reduced clearances, different venting, omission of suppression) is claimed, the authority having jurisdiction may accept large‑scale testing or hazard analyses per § 1207.1.7 and § 1207.1.6 as the basis for approval.

Common mistakes

  • Assuming cabinets only need to be lockable (some use unlocked racks). The code requires locked noncombustible cabinets for ESS in occupied work centers. § 1207.4.10
  • Placing cabinets beyond 10 feet from the equipment they support — this violates § 1207.4.10 unless documented otherwise. § 1207.4.10
  • Treating walk‑in units as usable rooms (offices, storage, break rooms) — walk‑in units with ESS are restricted to service access only. § 1207.4.12
  • Failing to check whether the ESS technology triggers explosion control requirements in Table 1207.6; that omission can lead to major retrofits. § 1207.6.3
  • Forgetting required signage and security requirements for ESS enclosures and walk‑in units (see § 1207.4.8 and § 1207.4.9). § 1207.4.8

Worked example — applying the rules with numbers

Scenario: A commercial office wants to place a lithium‑ion ESS cabinet inside a server room used by general staff (not ESS technicians). The ESS will support nearby UPS equipment.

Step‑by‑step:

  1. Because the ESS is in a room occupied by personnel not directly involved with ESS work, the ESS must be in a locked noncombustible cabinet and within 10 ft of the equipment it supports per § 1207.4.10. If the cabinet is 8 ft from the UPS, that meets the distance rule. § 1207.4.10
  2. Signage per § 1207.4.8 must be provided on or adjacent to the cabinet (e.g., “ENERGY STORAGE SYSTEM,” technology ID, “ENERGIZED ELECTRICAL CIRCUITS,” contact info). § 1207.4.8
  3. Store no combustibles inside the room and keep any combustible materials at least 3 feet from the cabinet. § 1207.4.6
  4. Determine whether the ESS technology requires explosion control by checking Table 1207.6. If Table 1207.6 indicates explosion control is required for the selected lithium‑ion battery configuration, provide explosion control per Section 911 as required by § 1207.6.3. If the owner can supply an approved UL 9540A test demonstrating no flammable gas liberation, the fire code official may waive explosion control under the exceptions in § 1207.6.3. § 1207.6.3
  5. Verify seismic support and floor loading compliance via the project structural calculations in accordance with Chapter 16 of the CBC and include the support/seismic restraint details in the construction documents per § 1207.4.4 and § 1207.1.5. § 1207.4.4

If any of those conditions are not met (e.g., cabinet 12 ft away, unlocked, combustible materials within 1 ft), the installation will not comply and will be subject to correction or refusal of permit issuance. § 1207.4.10

Related provisions

  • § 1207.4.8 — Signage for ESS enclosures and walk‑in units.
  • § 1207.4.6 — Combustible storage restrictions and minimum distances in occupied work centers.
  • § 1207.4.4 — Seismic and structural design reference to CBC Chapter 16 and floor loading limits.
  • § 1207.5.6 — Maximum enclosure size for outdoor walk‑in units (53 ft × 8 ft × 9.5 ft).
  • § 1207.1.5 — Construction documents must include support and seismic restraint details.
  • § 1207.1.7 — Large‑scale fire testing (UL 9540A) as a basis for approvals and exceptions.

Code references

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

  • CFC § 1207.4.2 High relevance — show source text

    1207.4.2 Working clearances. Access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment in accordance with the California Electrical Code and the manufacturer’s instructions.

    1207.4.3 Fire-resistance-rated separations. Rooms and other indoor areas containing ESS shall be separated from other areas of the building in accordance with Section 1207.7.4. ESS shall be permitted to be in the same room with the equipment they support.

    1207.4.4 Seismic and structural design. Stationary ESS shall comply with the seismic design requirements in Chapter 16 of the California Building Code, and shall not exceed the floor loading limitation of the building.

    1207.4.5 Vehicle impact protection. Where ESS are subject to impact by a motor vehicle, including forklifts, vehicle impact protection shall be provided in accordance with Section 312.

    1207.4.6 Combustible storage. Combustible materials shall not be stored in ESS rooms, areas or walk-in units. Combustible materials in occupied work centers covered by Section 1207.4.10 shall be stored at least 3 feet (914 mm) from ESS cabinets.

    1207.4.7 Toxic and highly toxic gases. ESS that have the potential to release toxic and highly toxic gas during charging, discharging and normal use conditions shall be provided with a hazardous exhaust system in accordance with Chapter 5 of the California Mechanical Code .

    1207.4.8 Signage. Approved signs shall be provided on or adjacent to all entry doors for ESS rooms or areas and on enclosures of ESS cabinets and walk-in units located outdoors, on rooftops or in open parking garages. Signs designed to meet both the requirements of this section and the California Electrical Code shall be permitted. The signage shall include the following or equivalent:

    1. “ENERGY STORAGE SYSTEM,” “BATTERY STORAGE SYSTEM,” “CAPACITOR ENERGY STORAGE SYSTEM” or the equivalent.

    2. The identification of the electrochemical ESS technology present.

    3. “ENERGIZED ELECTRICAL CIRCUITS.”

    4. Where water-reactive electrochemical ESS are present, the signage shall include “APPLY NO WATER.”

    5. Current contact information, including phone number, for personnel authorized to service the equipment and for fire mitigation personnel required by Section 1207.1.8.1.

    Exception: Existing electrochemical ESS shall be permitted to include the signage required at the time they were installed. (Material based on NFPA 855 2023 Ed.)

    1207.4.9 Security of installations. Rooms, areas and walk-in units in which electrochemical ESS are located shall be secured against unauthorized entry and safeguarded in an approved manner. Security barriers, fences, landscaping and other enclosures

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    shall not inhibit the required air flow to or exhaust from the electrochemical ESS and its components. (Material based on NFPA 855 2023 Ed.)

  • CFC § 1207.4.10 High relevance — show source text

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    ENERGY SYSTEMS

    shall not inhibit the required air flow to or exhaust from the electrochemical ESS and its components. (Material based on NFPA 855 2023 Ed.)

    1207.4.10 Occupied work centers. Electrochemical ESS located in rooms or areas occupied by personnel not directly involved with maintenance, service and testing of the systems shall comply with the following:

    1. Electrochemical ESS located in occupied work centers shall be housed in locked noncombustible cabinets or other enclosures to prevent access by unauthorized personnel.
    2. Where electrochemical ESS are contained in cabinets in occupied work centers, the cabinets shall be located within 10 feet (3048 mm) of the equipment that they support.
    3. Cabinets shall include signage complying with Section 1207.4.8. (Material based on NFPA 855 2023 Ed.)

    1207.4.11 Open rack installations. Where electrochemical ESS are installed in a separate equipment room and only authorized personnel have access to the room, they shall be permitted to be installed on an open rack for ease of maintenance. (Material based on NFPA 855 2023 Ed.)

    1207.4.12 Walk-in units. Walk-in units shall be entered only for inspection, maintenance and repair of ESS units and ancillary equipment, and shall not be occupied for other purposes.

    1207.5 Electrochemical ESS protection. The protection of electrochemical ESS shall be in accordance with Sections 1207.5.1 through 1207.5.8 where required by Sections 1207.7 through 1207.10. (Material based on NFPA 855 2023 Ed.)

    TABLE 1207.5—MAXIMUM ALLOWABLE QUANTITIES OF ELECTROCHEMICAL ESS Col2
    TECHNOLOGY MAXIMUM ALLOWABLE QUANTITIESa
    STORAGE BATTERIES STORAGE BATTERIES
    Flow batteriesb 600 kWh
    Lead-acid, all types Unlimited
    Lithium-ion 600 kWh
    Nickel-cadmium (Ni-Cd), nickel-metal hydride (NI-MH) and nickel zinc (Ni-Zn) Unlimited
    Sodium nickel chloride 600 kWh
    Zinc-manganese dioxide (Zn-MnO2) Unlimited
    Other battery technologies 200 kWh
    CAPACITORS CAPACITORS
    All types 20 kWh
    OTHER ELECTROCHEMICAL ESS OTHER ELECTROCHEMICAL ESS
    All types 20 kWh
    For SI: 1 kilowatt hour = 3.6 megajoules.
    a. For electrochemical ESS units rated in amp-hours, kWh shall equal rated voltage times the amp-hour rating divided by 1,000.
    b. Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.    		 For SI: 1 kilowatt hour = 3.6 megajoules.
    a. For electrochemical ESS units rated in amp-hours, kWh shall equal rated voltage times the amp-hour rating divided by 1,000.
    b. Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.
  • CFC § 1207.3.8 High relevance — show source text

    (Material based on NFPA 855 2023 Ed.)

    1207.3.8 Replacements. Replacements of ESS shall be considered new ESS installations and shall comply with the provisions of Section 1207 as applicable to new ESS. The ESS being replaced shall be decommissioned in accordance with Section 1207.2.3. (Material based on NFPA 855 2023 Ed.)

    1207.3.9 Reused and repurposed equipment. Equipment and materials shall only be reused or reinstalled as permitted in Section 104.9.1. Storage batteries previously used in other applications, such as electric vehicle propulsion, shall not be reused in applications regulated by Chapter 12 unless approved by the fire code official and unless the equipment is refurbished by a battery refurbishing company approved in accordance with UL 1974. (Material based on NFPA 855 2023 Ed.)

    1207.4 General installations requirements. Stationary and mobile ESS shall comply with the requirements of Sections 1207.4.1 through 1207.4.12.

    1207.4.1 Electrical disconnects. Where the ESS disconnecting means is not within sight of the main electrical service disconnecting means, placards or directories shall be installed at the location of the main electrical service disconnecting means indicating the location of stationary storage battery system disconnecting means in accordance with the California Electrical Code .

    Exception: Electrical disconnects for lead-acid and nickel-cadmium battery systems at facilities under the exclusive control of communications utilities and operating at less than 50 VAC and 60 VDC shall be permitted to have electrical disconnects signage in accordance with NFPA 76.

    1207.4.2 Working clearances. Access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment in accordance with the California Electrical Code and the manufacturer’s instructions.

    1207.4.3 Fire-resistance-rated separations. Rooms and other indoor areas containing ESS shall be separated from other areas of the building in accordance with Section 1207.7.4. ESS shall be permitted to be in the same room with the equipment they support.

    1207.4.4 Seismic and structural design. Stationary ESS shall comply with the seismic design requirements in Chapter 16 of the California Building Code, and shall not exceed the floor loading limitation of the building.

    1207.4.5 Vehicle impact protection. Where ESS are subject to impact by a motor vehicle, including forklifts, vehicle impact protection shall be provided in accordance with Section 312.

    1207.4.6 Combustible storage. Combustible materials shall not be stored in ESS rooms, areas or walk-in units. Combustible materials in occupied work centers covered by Section 1207.4.10 shall be stored at least 3 feet (914 mm) from ESS cabinets.

    1207.4.7 Toxic and highly toxic gases. ESS that have the potential to release toxic and highly toxic gas during charging, discharging and normal use conditions shall be provided with a hazardous exhaust system in accordance with Chapter 5 of the California Mechanical Code .

  • CFC § 1207.1.7. High relevance — show source text

    1. Lot lines.

    2. Public ways.

    3. Stored combustible materials.

    4. Locations where motor vehicles can be parked.

    5. Hazardous materials.

    6. Other exposure hazards.

    Exceptions:

    1. Clearances are permitted to be reduced to 3 feet (914 mm) where a 1-hour free-standing fire barrier suitable for exterior use and extending 5 feet (1524 mm) above and 5 feet (1524 mm) beyond the physical boundary of the ESS installation is provided to protect the exposure.
    2. Clearances are permitted to be reduced to 3 feet (914 mm) where a weatherproof enclosure constructed of noncombustible materials is provided over the ESS, and it has been demonstrated that a fire within the enclosure will not ignite combustible materials outside the enclosure based on large-scale fire testing complying with Section 1207.1.7. (Material based on NFPA 855 2023 Ed.)

    1207.9.4 Fire suppression systems. ESS located in walk-in units on rooftops or in walk-in units in open parking garages shall be provided with automatic fire suppression systems within the ESS enclosure in accordance with Section 1207.5.5. Areas containing ESS other than walk-in units in open parking structures on levels not open above to the sky shall be provided with an automatic fire suppression system complying with Section 1207.5.5.

    Exception: A fire suppression system is not required in open parking garages if large-scale fire testing complying with Section 1207.1.7 is provided that shows that a fire will not impact the exposures in Section 1207.9.3. (Material based on NFPA 855 2023 Ed.)

    1207.9.5 Rooftop installations. ESS and associated equipment that are located on rooftops and not enclosed by building construction shall comply with the following:

    1. Stairway access to the roof for emergency response and fire department personnel shall be provided either through a bulkhead from the interior of the building or a stairway on the exterior of the building.
    2. Service walkways at least 5 feet (1524 mm) in width shall be provided for service and emergency personnel from the point of access to the roof to the system.

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    1. ESS and associated equipment shall be located from the edge of the roof a distance equal to at least the height of the system, equipment or component but not less than 5 feet (1524 mm).
    2. The roofing materials under and within 5 feet (1524 mm) horizontally from an ESS or associated equipment shall be noncombustible or shall have a Class A rating when tested in accordance with ASTM E108 or UL 790.
    3. A Class I standpipe outlet shall be installed at an approved location on the roof level of the building or in the stairway bulkhead at the top level.
    4. The ESS shall be the minimum of 10 feet (3048 mm) from the fire service access point on the rooftop. (Material based on NFPA 855 2023 Ed.)

    1207.9.6 Open parking garages. ESS and associated equipment that are located in open parking garages shall comply with all of the following:

    1. ESS shall not be located within 50 feet (15 240 mm) of air inlets for building HVAC systems.
  • CFC § 1207.9.6 High relevance — show source text

    1207.9.6 Open parking garages. ESS and associated equipment that are located in open parking garages shall comply with all of the following:

    1. ESS shall not be located within 50 feet (15 240 mm) of air inlets for building HVAC systems.

    Exception: This distance shall be permitted to be reduced to 25 feet (7620 mm) if the automatic fire alarm system monitoring the radiant-energy sensing detectors de-energizes the ventilation system connected to the air intakes upon detection of fire.

    1. ESS shall not be located within 25 feet (7620 mm) of exits leading from the attached building where located on a covered level of the parking structure not directly open to the sky above.
    2. An approved fence with a locked gate or other approved barrier shall be provided to keep the general public at least 5 feet (1524 mm) from the outer enclosure of the ESS. (Material based on NFPA 855 2023 Ed.)

    1207.10 Mobile ESS equipment and operations. Mobile ESS equipment and operations shall comply with Sections 1207.10.1 through 1207.10.7.7. (Material based on NFPA 855 2023 Ed.)

    TABLE 1207.10—MOBILE ENERGY STORAGE SYSTEMS (ESS) Col2 Col3
    COMPLIANCE REQUIRED COMPLIANCE REQUIRED DEPLOYMENTa
    Feature Section Section
    All ESS installations 1207.4 Yesb
    Fire suppression systems 1207.5.5 Yesc
    Maximum allowable quantities 1207.5.2 Yes
    Maximum enclosure size 1207.5.6 Yes
    Means of egress separation 1207.5.8 Yes
    Size and separation 1207.5.1 Yesd
    Smoke and automatic fire detection 1207.5.4 Yese
    Technology-specific protection 1207.6 Yes
    Vegetation control 1207.5.7 Yes
    a. See Section 1207.10.2.
    b. Mobile operations on wheeled vehicles and trailers shall not be required to comply with Section 1207.4.4 seismic and structural load requirements.
    c. Fire suppression system connections to the water supply shall be permitted to use approved temporary connections.
    d. In walk-in units, spacing is not required between ESS units and the walls of the enclosure.
    e. Alarm signals are not required to be transmitted to an approved location for mobile ESS deployed 30 days or less.    		 a. See Section 1207.10.2.
    b. Mobile operations on wheeled vehicles and trailers shall not be required to comply with Section 1207.4.4 seismic and structural load requirements.
    c. Fire suppression system connections to the water supply shall be permitted to use approved temporary connections.
    d. In walk-in units, spacing is not required between ESS units and the walls of the enclosure.
    e. Alarm signals are not required to be transmitted to an approved location for mobile ESS deployed 30 days or less.    		 a. See Section 1207.10.2.
    b. Mobile operations on wheeled vehicles and trailers shall not be required to comply with Section 1207.4.4 seismic and structural load requirements.
    c. Fire suppression system connections to the water supply shall be permitted to use approved temporary connections.
    d.
  • CFC § 1207.1.7 High relevance — show source text

    Exceptions: (Material based on NFPA 855 2023 Ed.)

    1. Where approved, explosion control is permitted to be waived by the fire code official based on large-scale fire testing complying with Section 1207.1.7 that demonstrates that flammable gases are not liberated from electrochemical ESS cells or modules.

    2. Where approved, explosion control is permitted to be waived by the fire code official based on documentation provided in accordance with Section 104.2.2 that demonstrates that the electrochemical ESS technology to be used does not have the potential to release flammable gas concentrations in excess of 25 percent of the LFL anywhere in the room, area, walk-in unit or structure under thermal runaway or other fault conditions.

    3. Where approved, ESS cabinets that have no debris, shrapnel or enclosure pieces ejected during large-scale fire testing complying with Section 1207.1.5 shall be permitted in lieu of providing explosion control complying with Section 911.

    4. Explosion control is not required for lead-acid and nickel-cadmium battery systems less than 50 VAC, 60 VDC in telecommunication facilities under the exclusive control of communications utilities located in building spaces or walk-in units used exclusively for such installations.

    5. Explosion control is not required for lead-acid and nickel-cadmium systems used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, located in building spaces or walk-in units used exclusively for such installations.

    6. Explosion control is not required for lead-acid battery systems in uninterruptable power supplies listed and labeled in accordance with UL 1778, utilized for standby power applications, and housed in a single cabinet in a single fire area in buildings or walk-in units.

    1207.6.4 Safety caps. Where required by Table 1207.6 or elsewhere in this code, vented batteries and other ESS shall be provided with flame-arresting safety caps.

    1207.6.5 Thermal runaway. Where required by Table 1207.6 or elsewhere in this code, batteries and other ESS shall be provided with a listed device or other approved method to prevent, detect and minimize the impact of thermal runaway.

    1207.7 Indoor installations. Indoor ESS installations shall be in accordance with Sections 1207.7.1 through 1207.7.4. (Material based on NFPA 855 2023 Ed.)

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    TABLE 1207.7—INDOOR ESS INSTALLATIONS Col2 Col3 Col4
    COMPLIANCE REQUIRED COMPLIANCE REQUIRED DEDICATED-USE
    BUILDINGSa    		 NONDEDICATED-USE
    BUILDINGSb
    Feature Section Section Section
    Dwelling units and sleeping units 1207.7.3 NA Yes
    COMPLIANCE REQUIRED COMPLIANCE REQUIRED DEDICATED-USE
    BUILDINGSa    		 NONDEDICATED-USE
    BUILDINGSb
    Feature Section Section Section
    Elevation 1207.5.
  • CFC § 1207.4.8 High relevance — show source text

    1207.4.8 Signage. Approved signs shall be provided on or adjacent to all entry doors for ESS rooms or areas and on enclosures of ESS cabinets and walk-in units located outdoors, on rooftops or in open parking garages. Signs designed to meet both the requirements of this section and the California Electrical Code shall be permitted. The signage shall include the following or equivalent:

    1. “ENERGY STORAGE SYSTEM,” “BATTERY STORAGE SYSTEM,” “CAPACITOR ENERGY STORAGE SYSTEM” or the equivalent.

    2. The identification of the electrochemical ESS technology present.

    3. “ENERGIZED ELECTRICAL CIRCUITS.”

    4. Where water-reactive electrochemical ESS are present, the signage shall include “APPLY NO WATER.”

    5. Current contact information, including phone number, for personnel authorized to service the equipment and for fire mitigation personnel required by Section 1207.1.8.1.

    Exception: Existing electrochemical ESS shall be permitted to include the signage required at the time they were installed. (Material based on NFPA 855 2023 Ed.)

    1207.4.9 Security of installations. Rooms, areas and walk-in units in which electrochemical ESS are located shall be secured against unauthorized entry and safeguarded in an approved manner. Security barriers, fences, landscaping and other enclosures

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    shall not inhibit the required air flow to or exhaust from the electrochemical ESS and its components. (Material based on NFPA 855 2023 Ed.)

    1207.4.10 Occupied work centers. Electrochemical ESS located in rooms or areas occupied by personnel not directly involved with maintenance, service and testing of the systems shall comply with the following:

    1. Electrochemical ESS located in occupied work centers shall be housed in locked noncombustible cabinets or other enclosures to prevent access by unauthorized personnel.
    2. Where electrochemical ESS are contained in cabinets in occupied work centers, the cabinets shall be located within 10 feet (3048 mm) of the equipment that they support.
    3. Cabinets shall include signage complying with Section 1207.4.8. (Material based on NFPA 855 2023 Ed.)

    1207.4.11 Open rack installations. Where electrochemical ESS are installed in a separate equipment room and only authorized personnel have access to the room, they shall be permitted to be installed on an open rack for ease of maintenance. (Material based on NFPA 855 2023 Ed.)

    1207.4.12 Walk-in units. Walk-in units shall be entered only for inspection, maintenance and repair of ESS units and ancillary equipment, and shall not be occupied for other purposes.

    1207.5 Electrochemical ESS protection. The protection of electrochemical ESS shall be in accordance with Sections 1207.5.1 through 1207.5.8 where required by Sections 1207.7 through 1207.10. (Material based on NFPA 855 2023 Ed.)

  • CFC § 9.5 High relevance — show source text

    ** Outdoor walk-in units housing ESS shall not exceed 53 feet by 8 feet by 9.5 feet high (16 154 mm × 2438 mm × 2896 mm), not including bolt-on HVAC and related equipment, as approved. Outdoor walk-in units exceeding these limitations shall be considered indoor installations and comply with the requirements in Section 1207.7. (Material based on NFPA 855 2023 Ed.) 1207.5.7 Vegetation control. Areas within 10 feet (3048 mm) on each side of outdoor ESS shall be cleared of combustible vegetation and other combustible growth. Single specimens of trees, shrubbery or cultivated ground cover such as green grass, ivy, succulents or similar plants used as ground cover shall be permitted to be exempt provided that they do not form a means of readily transmitting fire. (Material based on NFPA 855 2023 Ed.) 1207.5.8 Means of egress separation. ESS located outdoors and in open parking garages shall be separated from any means of egress as required by the fire code official to ensure safe egress under fire conditions, but in no case less than 10 feet (3048 mm).

    Exception: The fire code official is authorized to approve a reduced separation distance if large-scale fire testing complying with Section 1207.1.7 is provided that shows that a fire involving the ESS will not adversely impact occupant egress. (Material based on NFPA 855 2023 Ed.)

    1207.6 Electrochemical ESS technology-specific protection. Electrochemical ESS installations shall comply with the requirements of this section in accordance with the applicable requirements of Table 1207.6. (Material based on NFPA 855 2023 Ed.)

    TABLE 1207.6—ELECTROCHEMICAL ESS TECHNOLOGY-SPECIFIC REQUIREMENTS Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10
    COMPLIANCE REQUIREDb COMPLIANCE REQUIREDb BATTERY TECHNOLOGY BATTERY TECHNOLOGY BATTERY TECHNOLOGY BATTERY TECHNOLOGY BATTERY TECHNOLOGY BATTERY TECHNOLOGY OTHER ESS
    AND BATTERY
    TECHNOLOGIESb    		 CAPACITOR
    ESSb
    Feature Section Lead-
    acid    		 Nickel
    cadmium
    (Ni-Cd),
    nickel-metal
    hydride
    (Ni-MH) and
    nickel zinc
    (Ni-Zn)    		 Zinc-
    manganese
    dioxide
    (Zn-MnO2)    		 Lithium-ion Flow Sodium
    nickel
    chloride    		 Sodium
    nickel
    chloride    		 Sodium
    nickel
    chloride
    Exhaust
    ventilation    		 1207.6.1 Yes Yes Yes No Yes No Yes Yes
    Explosion control 1207.6.
  • CFC § 1207.1.7. High relevance — show source text
    1. Clearances to buildings are permitted to be reduced to 3 feet (914 mm) where a weatherproof enclosure constructed of noncombustible materials is provided over the ESS, and it has been demonstrated that a fire within the enclosure will not ignite combustible materials outside the enclosure based on large-scale fire testing complying with Section 1207.1.7.

    1207.8.4 Exterior wall installations. ESS shall be permitted to be installed outdoors on exterior walls of buildings when all of the following conditions are met:

    1. The maximum energy capacity of individual ESS units shall not exceed 20 kWh.
    2. The ESS shall comply with applicable requirements in Section 1207.
    3. The ESS shall be installed in accordance with the manufacturer’s instructions and their listing.
    4. Individual ESS units shall be separated from each other by at least 3 feet (914 mm).
    5. The ESS shall be separated from doors, windows, operable openings into buildings or HVAC inlets by at least 5 feet (1524 mm).

    Exception: Where approved, smaller separation distances in Items 4 and 5 shall be permitted based on large-scale fire testing complying with Section 1207.1.7. (Material based on NFPA 855 2023 Ed.)

    12-20 2025 CALIFORNIA FIRE CODE

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

    ENERGY SYSTEMS

    1207.9 Special installations. Rooftop and open parking garage ESS installations shall comply with Sections 1207.9.1 through 1207.9.6.

    TABLE 1207.9—SPECIAL ESS INSTALLATIONS Col2 Col3 Col4
    COMPLIANCE REQUIRED COMPLIANCE REQUIRED ROOFTOPSa OPEN PARKING GARAGESb
    Feature Section Section Section
    All ESS installations 1207.4 Yes Yes
    Clearance to exposures 1207.9.3 Yes Yes
    Fire suppression systems 1207.9.4 Yes Yes
    Maximum allowable quantities 1207.5.2 Yes Yes
    Maximum enclosure size 1207.5.6 Yes Yes
    Means of egress separation 1207.5.8 Yes Yes
    Open parking garage installations 1207.9.6 No Yes
    Rooftop installations 1207.9.5 Yes No
    Size and separation 1207.5.1 Yes Yes
    Smoke and automatic fire detection 1207.5.4 Yes Yes
    Technology-specific protection 1207.6 Yes Yes
    a. See Section 1207.9.1.
    b. See Section 1207.9.2.    		 a. See Section 1207.9.1.
    b. See Section 1207.9.2.    		 a. See Section 1207.9.1.
    b. See Section 1207.9.2.    		 a. See Section 1207.9.1.
    b. See Section 1207.9.2.

    1207.9.1 Rooftop installations. For the purpose of Table 1207.9, rooftop ESS installations are those located on the roofs of buildings. (Material based on NFPA 855 2023 Ed.)

  • CFC § 1207.2.1. High relevance — show source text

    The quantities and types of ESS to be installed. 4. Manufacturer’s specifications, ratings and listings of each ESS. 5. Description of energy (battery) management systems and their operation. 6. Location and content of required signage. 7. Details on fire suppression, smoke or fire detection, thermal management, ventilation, exhaust and deflagration venting systems, if provided. 8. Support arrangement associated with the installation, including any required seismic restraint. 9. A commissioning plan complying with Section 1207.2.1. 10. A decommissioning plan complying with Section 1207.2.3. 11. A fire safety and evacuation plan in accordance with Section 404.

    1207.1.5.1 Utilities applicability. Plans and specifications associated with ESS owned and operated by electric utilities as a component of the electric grid that are considered critical infrastructure documents in accordance with the provisions of the North American Electric Reliability Corporation and other applicable governmental laws and regulations shall be made available to the fire code official for viewing based on the requirements of the applicable governmental laws and regulations. (Material based on NFPA 855 2023 Ed.)

    1207.1.6 Hazard mitigation analysis. A failure modes and effects analysis (FMEA) or other approved hazard mitigation analysis shall be provided in accordance with Section 104.2.2 under any of the following conditions:

    1. Where ESS technologies not specifically identified in Table 1207.1.3 are provided.
    2. More than one ESS technology is provided in a single fire area where there is a potential for adverse interaction between technologies.
    3. Where allowed as a basis for increasing maximum allowable quantities. See Section 1207.5.2.
    4. Where required by the fire code official to address a potential hazard with an ESS installation that is not addressed by existing requirements.

    1207.1.6.1 Fault condition. The hazard mitigation analysis shall evaluate the consequences of the following failure modes. Only single failure modes shall be considered.

    1. A thermal runaway condition in a single electrochemical ESS unit.

    2. A mechanical failure of a nonelectrochemical ESS unit.

    3. Failure of any battery (energy) management system or fire protection system within the ESS equipment that is not covered by the product listing failure mode effects analysis (FMEA).

    4. Failure of any required protection system external to the ESS, including but not limited to ventilation (HVAC), exhaust ventilation, smoke detection, fire detection, gas detection or fire suppression system. (Material based on NFPA 855 2023 Ed.)

    1207.1.6.2 Analysis approval. The fire code official is authorized to approve the hazardous mitigation analysis provided that the consequences of the hazard mitigation analysis demonstrate:

    1. Fires will be contained within unoccupied ESS rooms or areas for the minimum duration of the fire-resistance-rated separations identified in Section 1207.7.4.
    2. Fires involving the ESS will allow occupants or the general public to evacuate to a safe location. (Material based on NFPA 855 2023 Ed.)

    1207.1.6.3 Additional protection measures. Construction, equipment and systems that are required for the ESS to comply with the hazardous mitigation analysis, including but not limited to those specifically described in Section 1207, shall be installed, maintained and tested in accordance with nationally recognized standards and specified design parameters.

  • CFC § 1207.6.2 High relevance — show source text

    1207.6.2 Spill control and neutralization. Where required by Table 1207.6 or elsewhere in this code, areas containing free-flowing liquid electrolyte or hazardous materials shall be provided with spill control and neutralization in accordance with this section. (Material based on NFPA 855 2023 Ed.)

    1207.6.2.1 Spill control. Spill control shall be provided to prevent the flow of liquid electrolyte or hazardous materials to adjoining rooms or areas. The method shall be capable of containing a spill from the single largest battery or vessel. (Material based on NFPA 855 2023 Ed.)

    1207.6.2.2 Neutralization. An approved method that is capable of neutralizing spilled liquid electrolyte from the largest battery or vessel to a pH between 5.0 and 9.0 shall be provided. (Material based on NFPA 855 2023 Ed.)

    1207.6.2.3 Communications utilities. The requirements of Section 1207.6.2 shall apply only when the aggregate capacity of multiple vessels exceeds 1,000 gallons (3785 L) for lead-acid and nickel-cadmium battery systems operating at less than 50 VAC and 60 VDC that are located at facilities under the exclusive control of communications utilities, and those facilities comply with NFPA 76 in addition to applicable requirements of this code.

    1207.6.3 Explosion control. Where required by Table 1207.6 or elsewhere in this code, explosion control complying with Section 911 shall be provided for rooms, areas, ESS cabinets or ESS walk-in units containing electrochemical ESS technologies.

    Exceptions: (Material based on NFPA 855 2023 Ed.)

    1. Where approved, explosion control is permitted to be waived by the fire code official based on large-scale fire testing complying with Section 1207.1.7 that demonstrates that flammable gases are not liberated from electrochemical ESS cells or modules.

    2. Where approved, explosion control is permitted to be waived by the fire code official based on documentation provided in accordance with Section 104.2.2 that demonstrates that the electrochemical ESS technology to be used does not have the potential to release flammable gas concentrations in excess of 25 percent of the LFL anywhere in the room, area, walk-in unit or structure under thermal runaway or other fault conditions.

    3. Where approved, ESS cabinets that have no debris, shrapnel or enclosure pieces ejected during large-scale fire testing complying with Section 1207.1.5 shall be permitted in lieu of providing explosion control complying with Section 911.

    4. Explosion control is not required for lead-acid and nickel-cadmium battery systems less than 50 VAC, 60 VDC in telecommunication facilities under the exclusive control of communications utilities located in building spaces or walk-in units used exclusively for such installations.

    5. Explosion control is not required for lead-acid and nickel-cadmium systems used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, located in building spaces or walk-in units used exclusively for such installations.

    6. Explosion control is not required for lead-acid battery systems in uninterruptable power supplies listed and labeled in accordance with UL 1778, utilized for standby power applications, and housed in a single cabinet in a single fire area in buildings or walk-in units.

  • CFC § 1207.8.2 High relevance — show source text

    1207.8.2 Installations near exposures. For the purpose of Table 1207.8, installations near exposures include all outdoor ESS installations that do not comply with Section 1207.8.1 remote outdoor location requirements. (Material based on NFPA 855 2023 Ed.)

    1207.8.3 Clearance to exposures. ESS located outdoors shall be separated by a minimum of 10 feet (3048 mm) from the following exposures:

    1. Lot lines.

    2. Public ways.

    3. Buildings.

    4. Stored combustible materials.

    5. Hazardous materials.

    6. High-piled stock.

    7. Other exposure hazards.

    Exceptions: (Material based on NFPA 855 2023 Ed.)

    1. Clearances are permitted to be reduced to 3 feet (914 mm) where a 1-hour free-standing fire barrier suitable for exterior use and extending 5 feet (1524 mm) above and 5 feet (1524 mm) beyond the physical boundary of the ESS installation is provided to protect the exposure.

    2. Clearances to buildings are permitted to be reduced to 3 feet (914 mm) where noncombustible exterior walls with no openings or combustible overhangs are provided on the wall adjacent to the ESS and the fire-resistance rating of the exterior wall is a minimum of 2 hours.

    3. Clearances to buildings are permitted to be reduced to 3 feet (914 mm) where a weatherproof enclosure constructed of noncombustible materials is provided over the ESS, and it has been demonstrated that a fire within the enclosure will not ignite combustible materials outside the enclosure based on large-scale fire testing complying with Section 1207.1.7.

    1207.8.4 Exterior wall installations. ESS shall be permitted to be installed outdoors on exterior walls of buildings when all of the following conditions are met:

    1. The maximum energy capacity of individual ESS units shall not exceed 20 kWh.
    2. The ESS shall comply with applicable requirements in Section 1207.
    3. The ESS shall be installed in accordance with the manufacturer’s instructions and their listing.
    4. Individual ESS units shall be separated from each other by at least 3 feet (914 mm).
    5. The ESS shall be separated from doors, windows, operable openings into buildings or HVAC inlets by at least 5 feet (1524 mm).

    Exception: Where approved, smaller separation distances in Items 4 and 5 shall be permitted based on large-scale fire testing complying with Section 1207.1.7. (Material based on NFPA 855 2023 Ed.)

    12-20 2025 CALIFORNIA FIRE CODE

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

    ENERGY SYSTEMS

    1207.9 Special installations. Rooftop and open parking garage ESS installations shall comply with Sections 1207.9.1 through 1207.9.6.

Frequently asked questions

Can an ESS cabinet in an occupied office be open‑rack instead of enclosed?

No. In rooms or areas occupied by personnel not directly involved with ESS maintenance, the ESS must be housed in locked noncombustible cabinets or other enclosures per § 1207.4.10. Open‑rack installations are only allowed in separate equipment rooms with restricted access.

Are walk‑in units allowed to be used as storage rooms or break rooms?

No. § 1207.4.12 restricts entry to walk‑in units to inspection, maintenance and repair of ESS units and ancillary equipment; they shall not be occupied for other purposes.

When is explosion control required for a cabinet or walk‑in unit?

Explosion control is required where Table 1207.6 or other code provisions indicate and must comply with Section 911; exceptions may apply when large‑scale testing or acceptable documentation is provided to the fire code official per § 1207.6.3.

Is there a size limit for outdoor walk‑in units?

Yes — outdoor walk‑in units housing ESS shall not exceed 53 ft × 8 ft × 9.5 ft; larger units are treated as indoor installations and must meet indoor ESS rules. § 1207.5.6

Do ESS cabinets need special ventilation?

The code requires technology‑specific protection (exhaust/ventilation) where Table 1207.6 or other provisions require it (see Table 1207.6 and related sections). Confirm requirements for the chosen battery technology. § 1207.6 and § 1207.6.1 (see Table 1207.6 references).

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