CFC · California Fire Code

What rules apply to mobile ESS (temporary deployment, charging, and storage)?

Mobile ESS (trailers, containerized batteries) used temporarily must follow the California Fire Code rules in §1207.10: get the right permits and documents, meet 30‑day default deployment limits (longer needs extra rules/permits), keep minimum clearances (10 ft; 50 ft to large public seating/tents), provide fencing and signage, use temporary electrical connections per UL 9540 and the California Electrical Code, and for utility substations mobile units up to 90 days can be excluded from stationary ESS threshold counts if they meet §1207.10 and are used only during testing/repair/replacement. file

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Last reviewed: July 6, 2026

What the code requires — plain English

The California Fire Code requires that mobile ESS (mobile electrical energy storage systems) used for temporary deployment, charging and storage must meet specific permit, siting, separation, fencing, signage, electrical connection and duration rules in § 1207.10. Mobile units used at utility substations for short-term replacement or testing can be excluded from stationary ESS threshold counts when they comply with § 1207.10 and meet the conditions of § 1207.1.2.

The single most important practical rule: if a mobile ESS will be deployed at a utility substation for up to 90 days during testing/repair/replacement and it complies with § 1207.10, it does not add to the stationary ESS thresholds in Table 1207.1.3 — but it still must meet the siting, permit and safety requirements of § 1207.10.

Requirements in detail

Definitions (how the code uses terms)

  • Charging and storage: operation where mobile ESS are charged and stored so they are ready for deployment (or after deployment). See § 1207.10.1.
  • Deployment: operation where mobile ESS are located at a site other than the charging/storage site and are providing power. See § 1207.10.2.

Permits and documentation

  • Both construction permits (for charging/storage locations) and operational permits (for deployments) are required per § 1207.10.3 and § 1207.1.4. Provide construction documents per § 1207.1.5 and deployment-specific documentation listed in § 1207.10.4.1 (site layout, signage, fencing, local staging stops, wiring description, emergency contacts, expected connect/disconnect dates, etc.).

Charging & storage (treated as permanent installations)

  • Locations where mobile ESS are charged or stored are treated as permanent ESS installations and must comply with the relevant indoor/outdoor/rooftop rules (§ 1207.10.6 referencing §§ 1207.7, 1207.8, 1207.9). Temporary wiring and temporary suppression connections are allowed as exceptions where explicitly noted.

Deployment limits, siting and clearances

  • Default maximum deployment duration is 30 days (deployments >30 days must follow the charging/storage rules in § 1207.10.6; deployments may be extended up to 180 days with additional permits). § 1207.10.7.1.
  • Restricted locations: deployed mobile ESS shall not be located indoors, in covered parking garages, on rooftops, below grade or under building overhangs (§ 1207.10.7.2).
  • Clearance to exposures: minimum 10 feet from public ways, buildings, stored combustible materials, hazardous materials, high-piled storage and other hazards; 50 feet separation from public seating areas and tents/canopies/membrane structures with occupant load ≥ 30 (§ 1207.10.7.3).

Security, fencing, signs and no-smoking

  • Provide an approved fence or barrier keeping the public at least 5 feet from the outer enclosure, with a locked gate or approved barrier (§ 1207.10.7.6).
  • No smoking within 10 feet; post signs in accordance with Section 310 (§ 1207.10.7.7).
  • Required signage for ESS rooms/enclosures applies (see general signage rules in § 1207.4.8).

Electrical connections and wiring

  • Electrical connections must follow manufacturer instructions and the UL 9540 listing; temporary wiring is permitted when it also complies with the California Electrical Code. Fixed electrical wiring is not allowed for deployed mobile ESS (§ 1207.10.7.4).

Local staging and transit parking

  • While in transit between charging/storage and deployment, mobile ESS shall not be parked within 100 feet of an occupied building for more than 1 hour during transit unless approved by the fire code official at permit issuance (§ 1207.10.7.5).

Compliance matrix — quick reference table

Decision item Key value / requirement Code Reference
Default maximum deployment duration 30 days (longer → comply with charging/storage rules; up to 180 days with additional permits) § 1207.10.7.1
Utility substation threshold exception Mobile ESS at substations ≤ 90 days may NOT be added to stationary ESS thresholds if conditions met § 1207.1.2
Deployment restricted locations Not allowed: indoors, covered parking garages, rooftops, below grade, under overhangs § 1207.10.7.2
Minimum clearance to exposures 10 feet minimum to public ways/buildings/combustible/hazardous/high-piled § 1207.10.7.3
Clearance to seating/tents (large) 50 feet from public seating and tents/canopies with occupant load ≥ 30 § 1207.10.7.3
Fencing / public barrier 5 feet clearance from general public; fence with locked gate or approved barrier § 1207.10.7.6
Smoking Prohibited within 10 feet; signs required § 1207.10.7.7
Electrical connections Per manufacturer and UL 9540; temporary wiring ok if per California Electrical Code; no fixed wiring for deployed units § 1207.10.7.4
Charging/storage rule Charging/storage treated as permanent ESS: follow § 1207.7/1207.8/1207.9 as applicable § 1207.10.6
Permit & documents Construction permit for charging/storage; operational permit for deployments; submit construction docs and deployment info per § 1207.1.5 and § 1207.10.4.1 §§ 1207.10.3, 1207.1.5, 1207.10.4.1 file

Technology & threshold context

  • Threshold energy capacities used to determine when stationary ESS must comply with full Section 1207 are in Table 1207.1.3 (e.g., lithium‑ion: 20 kWh, lead‑acid: 70 kWh). Mobile ESS capacity and whether they count toward a stationary installation’s thresholds is governed by § 1207.1.2 for substations and by compliance with § 1207.10 generally. file

Exceptions & special cases

  • Mobile ESS used to temporarily provide power to lead‑acid and nickel‑cadmium systems used for DC control or safe shutdown at facilities under the exclusive control of the electric utility and located outdoors or in spaces used exclusively for such installations may be excepted in certain provisions (see the exception language in § 1207.10.1 and § 1207.10.2).
  • Mobile operations on wheeled vehicles and trailers are not required to comply with the seismic/structural load requirements of § 1207.4.4 (see Table 1207.10 notes).
  • Temporary electrical wiring and temporary fire suppression connections are allowed as specific exceptions where they comply with manufacturer instructions, UL 9540 listing and the California Electrical Code or approved temporary connection standards respectively (§ 1207.10.6 notes and Table 1207.10 footnotes).

If you need to rely on an exception (for example, extended deployment at a substation or use of lead‑acid units), verify the exact exception text with the fire code official and include the required documentation at permit application; the code includes specific qualification language. file

Common mistakes

  • Assuming mobile ESS never need permits. (They do: construction permits for charging/storage and operational permits for deployments per § 1207.10.3 and § 1207.1.4.)
  • Forgetting that deployments are limited to 30 days by default — longer deployments require compliance with charging/storage rules or additional permits. Check § 1207.10.7.1.
  • Installing fixed electrical wiring at a deployed site — the code prohibits fixed wiring for deployed mobile ESS; connections must be temporary and follow UL 9540/manufacturer instructions and the California Electrical Code (§ 1207.10.7.4).
  • Placing deployed units too close to public seating, tents, buildings or combustible/hazardous exposures — observe the 10 ft and 50 ft rules in § 1207.10.7.3.
  • Relying on the 90‑day substation threshold exception without confirming the mobile unit fully complies with § 1207.10 and is used only during testing/repair/retrofit/replacement (see § 1207.1.2).

Worked example

Scenario: An electric utility will temporarily replace a stationary lithium‑ion ESS at a substation. The stationary unit is offline for repairs. The utility brings in two mobile lithium‑ion trailers, each 10 kWh, to provide power while the stationary unit is replaced. The planned deployment is 60 days.

How the code applies:

  • Threshold counting: Because this is a utility substation and the mobile units are being used only while the stationary ESS is being repaired/replaced, the mobile ESS do not have to be counted toward the stationary installation’s threshold for up to 90 days, provided the mobile units comply with § 1207.10 and the utility meets the condition in § 1207.1.2.
  • Duration & compliance: Planned deployment is 60 days, which exceeds the default 30‑day deployment limit; the mobile deployment must therefore comply with the charging/storage requirements in § 1207.10.6 (i.e., be treated like a permanent installation for applicable protections such as indoor/outdoor rules) or obtain additional operational permits for a deployment longer than 30 days (and up to 180 days with approvals) per § 1207.10.7.1. file
  • Siting & safety: The deployment site must provide ≥10 ft separations to buildings/public ways/etc., 50 ft to public seating/tents if applicable, fencing to keep the public 5 ft away, signage and a no‑smoking zone of 10 ft. Electrical connections must be temporary, per manufacturer/UL 9540 and the California Electrical Code; fixed wiring is not allowed. Staging while in transit must avoid parking within 100 ft of an occupied building for >1 hour unless authorized at permit issuance. See §§ 1207.10.7.3–1207.10.7.7 and § 1207.10.7.4. file

Bottom line: the 60‑day utility deployment can avoid adding to threshold counts under § 1207.1.2, but the operation must either meet the charging/storage (permanent) protective requirements in § 1207.10.6 or obtain the required additional permits to lawfully operate for longer than 30 days. file

Related provisions (quick links)

  • § 1207.10 — Mobile ESS equipment and operations (whole mobile ESS section).
  • § 1207.10.6 — Charging and storage treated as permanent ESS (indoor/outdoor/rooftop rules).
  • § 1207.10.7.1 — Deployment duration limits (30, 180 day notes).
  • § 1207.10.7.2–7.7 — Deployment siting, clearances, wiring, staging, fencing, smoking and related operational rules. file
  • § 1207.1.2 — Mobile ESS counting toward thresholds and the 90‑day utility allowance.
  • Table 1207.1.3 — ESS threshold energy capacities by technology (e.g., lithium‑ion 20 kWh).
  • § 1207.1.4 / § 1207.1.5 — Permits and construction document requirements for ESS.

Code references

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

  • CFC § 1207.10.7 High relevance — show source text

    Exceptions:

    1. Electrical connections shall be permitted to be made using temporary wiring complying with the manufacturer’s instructions, the UL 9540 listing and the California Electrical Code .
    2. Fire suppression system connections to the water supply shall be permitted to use approved temporary connections. (Material based on NFPA 855 2023 Ed.)

    1207.10.7 Deployed mobile ESS requirements. Deployed mobile ESS equipment and operations shall comply with this section and Table 1207.10. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.1 Duration. The duration of mobile ESS deployment shall not exceed 30 days.

    Exceptions:

    1. Mobile ESS deployments that provide power for durations longer than 30 days shall comply with Section 1207.10.6.
    2. Mobile ESS deployments shall not exceed 180 days unless additional operational permits are obtained. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.2 Restricted locations. Deployed mobile ESS operations shall not be located indoors, in covered parking garages, on rooftops, below grade or under building overhangs. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.3 Clearance to exposures. Deployed mobile ESS shall be separated by a minimum of 10 feet (3048 mm) from the following exposures:

    1. Public ways.

    2. Buildings.

    3. Stored combustible materials.

    4. Hazardous materials.

    5. High-piled storage.

    6. Other exposure hazards.

    Deployed mobile ESS shall be separated by a minimum of 50 feet (15 240 mm) from public seating areas and from tents, canopies and membrane structures with an occupant load of 30 or more. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.4 Electrical connections. Electrical connections shall be made in accordance with the manufacturer’s instructions and the UL 9540 listing. Temporary wiring for electrical power connections shall comply with the California Electrical Code . Fixed electrical wiring shall not be provided. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.5 Local staging. Mobile ESS in transit from the charging and storage location to the deployment location and back shall not be parked within 100 feet (30 480 mm) of an occupied building for more than 1 hour during transit, unless specifically approved by the fire code official when the permit is issued. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.6 Fencing. 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 a deployed mobile ESS. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.7 Smoking. Smoking shall be prohibited within 10 feet (3048 mm) of mobile ESS. Signs shall be posted in accordance with Section 310.

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    1207.11 ESS in Group R-3 and R-4 occupancies. ESS in Group R-3 and R-4 occupancies shall be in accordance with Sections 1207.11.1 through 1207.11.9.

    Exceptions:

  • CFC § 1207.10.7.5. High relevance — show source text

    1. Location and layout diagram of the area in which the mobile ESS is to be deployed, including a scale diagram of all nearby exposures.

    2. Location and content of signage, including no smoking signs.

    3. Description of fencing to be provided around the ESS, including locking methods.

    4. Details on fire suppression, smoke and automatic fire detection, system monitoring, thermal management, exhaust ventilation and explosion control, if provided.

    5. For deployment, the intended duration of operation, including anticipated connection and disconnection times and dates.

    6. Location and description of local staging stops during transit to the deployment site. See Section 1207.10.7.5.

    7. Description of the temporary wiring, including connection methods, conductor type and size, and circuit overcurrent protection to be provided.

    8. Description of how fire suppression system connections to water supplies or extinguishing agents are to be provided.

    9. Contact information for personnel who are responsible for maintaining and servicing the equipment, and responding to emergencies as required by Section 1207.1.8.1. (Material based on NFPA 855 2023 Ed.)

    1207.10.5 Approved locations. Locations where mobile ESS are charged, stored and deployed shall be restricted to the locations established on the construction and operational permits. (Material based on NFPA 855 2023 Ed.)

    1207.10.6 Charging and storage. Installations where mobile ESS are charged and stored shall be treated as permanent ESS indoor or outdoor installations, and shall comply with the following sections, as applicable:

    1. Indoor charging and storage shall comply with Section 1207.7.
    2. Outdoor charging and storage shall comply with Section 1207.8.
    3. Charging and storage on rooftops and in open parking garages shall comply with Section 1207.9.

    Exceptions:

    1. Electrical connections shall be permitted to be made using temporary wiring complying with the manufacturer’s instructions, the UL 9540 listing and the California Electrical Code .
    2. Fire suppression system connections to the water supply shall be permitted to use approved temporary connections. (Material based on NFPA 855 2023 Ed.)

    1207.10.7 Deployed mobile ESS requirements. Deployed mobile ESS equipment and operations shall comply with this section and Table 1207.10. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.1 Duration. The duration of mobile ESS deployment shall not exceed 30 days.

    Exceptions:

    1. Mobile ESS deployments that provide power for durations longer than 30 days shall comply with Section 1207.10.6.
    2. Mobile ESS deployments shall not exceed 180 days unless additional operational permits are obtained. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.2 Restricted locations. Deployed mobile ESS operations shall not be located indoors, in covered parking garages, on rooftops, below grade or under building overhangs. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.3 Clearance to exposures. Deployed mobile ESS shall be separated by a minimum of 10 feet (3048 mm) from the following exposures:

    1. Public ways.

    2. Buildings.

    3. Stored combustible materials.

    4. Hazardous materials.

    5. High-piled storage.

    6. Other exposure hazards.

  • CFC § 1207.10.2 High relevance — show source text

    Exception: Mobile ESS used to temporarily provide power to lead-acid and nickel-cadmium systems that are used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, and located outdoors or in building spaces used exclusively for such installations. (Material based on NFPA 855 2023 Ed.)

    1207.10.2 Deployment. For the purpose of Section 1207.10, deployment covers operations where mobile ESS are located at a site other than the charging and storage site and are being used to provide power.

    Exception: Mobile ESS used to temporarily provide power to lead-acid and nickel-cadmium systems that are used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, and located outdoors or in building spaces used exclusively for such installations. (Material based on NFPA 855 2023 Ed.)

    1207.10.3 Permits. Construction and operational permits shall be provided for charging and storage of mobile ESS and operational permits shall be provided for deployment of mobile ESS as required by Section 1207.1.4.

    1207.10.4 Construction documents. Construction documents complying with Section 1207.1.5 shall be provided with the construction permit application for mobile ESS charging and storage locations.

    1207.10.4.1 Deployment documents. The following information shall be provided with the operation permit applications for mobile ESS deployments:

    1. Relevant information for the mobile ESS equipment and protection measures in the construction documents required by Section 1207.1.5.

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    1. Location and layout diagram of the area in which the mobile ESS is to be deployed, including a scale diagram of all nearby exposures.

    2. Location and content of signage, including no smoking signs.

    3. Description of fencing to be provided around the ESS, including locking methods.

    4. Details on fire suppression, smoke and automatic fire detection, system monitoring, thermal management, exhaust ventilation and explosion control, if provided.

    5. For deployment, the intended duration of operation, including anticipated connection and disconnection times and dates.

    6. Location and description of local staging stops during transit to the deployment site. See Section 1207.10.7.5.

    7. Description of the temporary wiring, including connection methods, conductor type and size, and circuit overcurrent protection to be provided.

    8. Description of how fire suppression system connections to water supplies or extinguishing agents are to be provided.

    9. Contact information for personnel who are responsible for maintaining and servicing the equipment, and responding to emergencies as required by Section 1207.1.8.1. (Material based on NFPA 855 2023 Ed.)

    1207.10.5 Approved locations. Locations where mobile ESS are charged, stored and deployed shall be restricted to the locations established on the construction and operational permits. (Material based on NFPA 855 2023 Ed.)

    1207.10.6 Charging and storage. Installations where mobile ESS are charged and stored shall be treated as permanent ESS indoor or outdoor installations, and shall comply with the following sections, as applicable:

    1. Indoor charging and storage shall comply with Section 1207.7.
    2. Outdoor charging and storage shall comply with Section 1207.8.
    3. Charging and storage on rooftops and in open parking garages shall comply with Section 1207.9.
  • 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 § 1207.10.7.4 High relevance — show source text

    1207.10.7.4 Electrical connections. Electrical connections shall be made in accordance with the manufacturer’s instructions and the UL 9540 listing. Temporary wiring for electrical power connections shall comply with the California Electrical Code . Fixed electrical wiring shall not be provided. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.5 Local staging. Mobile ESS in transit from the charging and storage location to the deployment location and back shall not be parked within 100 feet (30 480 mm) of an occupied building for more than 1 hour during transit, unless specifically approved by the fire code official when the permit is issued. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.6 Fencing. 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 a deployed mobile ESS. (Material based on NFPA 855 2023 Ed.)

    1207.10.7.7 Smoking. Smoking shall be prohibited within 10 feet (3048 mm) of mobile ESS. Signs shall be posted in accordance with Section 310.

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    1207.11 ESS in Group R-3 and R-4 occupancies. ESS in Group R-3 and R-4 occupancies shall be in accordance with Sections 1207.11.1 through 1207.11.9.

    Exceptions:

    1. ESS listed and labeled in accordance with UL 9540 and marked “For use in residential dwelling units,” where installed in accordance with the manufacturer’s instructions and the California Electrical Code .

    2. ESS rated less than 1 kWh (3.6 megajoules).

    1207.11.1 Equipment listings. ESS shall be listed and labeled in accordance with UL 9540.

    1207.11.2 Installation. ESS shall be installed in accordance with the manufacturer’s instructions and their listing. (Material based on NFPA 855 2023 Ed.)

    1207.11.2.1 Spacing. Individual ESS units shall be separated from each other by at least 3 feet (914 mm) except where smaller separation distances are documented to be adequate based on large-scale fire testing complying with Section 1207.1.7.

    1207.11.3 Location. ESS shall be installed only in the following locations:

    1. Detached garages and detached accessory structures.
    2. Attached garages separated from the dwelling unit living space in accordance with Section R302.6.
    3. Outdoors or on the exterior side of exterior walls located not less than 3 feet (914 mm) from doors and windows directly entering the dwelling unit.
    4. Enclosed utility closets, basements, and storage or utility spaces within dwelling units and sleeping units with finished or noncombustible walls and ceilings. Walls and ceilings of unfinished wood-framed construction shall be provided with not less than [5] / 8 -inch (15.9 mm) Type X gypsum wallboard.

    ESS shall not be installed in sleeping rooms, or in closets or spaces opening directly into sleeping rooms. (Material based on NFPA 855 2023 Ed.)

  • CFC § 1206.13 High relevance — show source text

    1206.13 Group R-3 and R-4 fuel cell vehicle energy storage system use. The temporary use of the dwelling unit owner or occupant’s fuel cell-powered electric vehicle to power a Group R-3 or R-4 dwelling while parked in an attached or detached garage or outside shall comply with the vehicle manufacturer’s instructions and the California Electrical Code .

    SECTION 1207—ELECTRICAL ENERGY STORAGE SYSTEMS (ESS)

    1207.1 General. The provisions in this section are applicable to stationary and mobile electrical energy storage systems (ESS).

    Exception: ESS in Group R-3 and R-4 occupancies shall only be required to comply with Section 1207.11 except where Section 1207.11.4 requires compliance with Sections 1207.1 through 1207.9.

    1207.1.1 Utilities and industrial applications. This section shall not apply to capacitors and capacitor equipment for electric utilities and industrial facilities used in applications such as flexible AC transmission (FACTS) devices, filter capacitor banks, power factor correction, and standalone capacitor banks for voltage correction and stabilization. (Material based on NFPA 855 2023 Ed.)

    1207.1.2 Mobile ESS. Mobile ESS deployed at an electric utility substation or generation facility for 90 days or less shall not add to the threshold values in Table 1207.1.3 for the stationary ESS installation if both of the following conditions apply:

    1. The mobile ESS complies with Section 1207.10.
    2. The mobile ESS is being used only during periods in which the facility’s stationary ESS is being tested, repaired, retrofitted or replaced. (Material based on NFPA 855 2023 Ed.)

    1207.1.3 Scope. ESS having capacities exceeding the values shown in Table 1207.1.3 shall comply with this section. (Material based on NFPA 855 2023 Ed.)

    TABLE 1207.1.3—ENERGY STORAGE SYSTEM (ESS) THRESHOLD QUANTITIES Col2
    TECHNOLOGY ENERGY CAPACITYa
    Capacitor ESS 3 kWh
    Flow batteriesb 20 kWh
    Lead-acid batteries, all types 70 kWhc
    Lithium-ion batteries 20 kWh
    Nickel-cadmium (Ni-Cd), nickel metal hydride (Ni-MH) and nickel zinc (Ni-Zn) batteries 70 kWh
    Nonelectrochemical ESSd 70 kWh
    Other battery technologies 10 kWh
    Other electrochemical ESS technologies 3 kWh
    Sodium nickel chloride batteries 70 kWh
    Zinc manganese dioxide batteries (Zn-MnO2) 70 kWh
    For SI: 1 kilowatt hour = 3.6 megajoules.
    a. Energy capacity is the total energy capable of being stored (nameplate rating), not the usable energy rating. For units rated in amp-hours, kWh shall equal rated voltage
    times amp-hour rating divided by 1,000.
    b. Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.
    c. Fifty gallons of lead-acid battery electrolyte shall be considered equivalent to 70 kWh.
    d. Covers nonelectrochemical technologies such as flywheel and thermal ESS.    		 For SI: 1 kilowatt hour = 3.6 megajoules.
    a. Energy capacity is the total energy capable of being stored (nameplate rating), not the usable energy rating.
  • CFC § 1207.10.2. High relevance — show source text

    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. 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.|

    1207.10.1 Charging and storage. For the purpose of Section 1207.10, charging and storage covers the operation where mobile ESS are charged and stored so they are ready for deployment to another site, and where they are charged and stored after a deployment.

    Exception: Mobile ESS used to temporarily provide power to lead-acid and nickel-cadmium systems that are used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, and located outdoors or in building spaces used exclusively for such installations. (Material based on NFPA 855 2023 Ed.)

    1207.10.2 Deployment. For the purpose of Section 1207.10, deployment covers operations where mobile ESS are located at a site other than the charging and storage site and are being used to provide power.

    Exception: Mobile ESS used to temporarily provide power to lead-acid and nickel-cadmium systems that are used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, and located outdoors or in building spaces used exclusively for such installations. (Material based on NFPA 855 2023 Ed.)

    1207.10.3 Permits. Construction and operational permits shall be provided for charging and storage of mobile ESS and operational permits shall be provided for deployment of mobile ESS as required by Section 1207.1.4.

    1207.10.4 Construction documents. Construction documents complying with Section 1207.1.5 shall be provided with the construction permit application for mobile ESS charging and storage locations.

    1207.10.4.1 Deployment documents. The following information shall be provided with the operation permit applications for mobile ESS deployments:

    1. Relevant information for the mobile ESS equipment and protection measures in the construction documents required by Section 1207.1.5.

    12-22 2025 CALIFORNIA FIRE CODE

  • CFC § 1207.1.3 High relevance — show source text
    TABLE 1207.1.3—ENERGY STORAGE SYSTEM (ESS) THRESHOLD QUANTITIES Col2
    TECHNOLOGY ENERGY CAPACITYa
    Capacitor ESS 3 kWh
    Flow batteriesb 20 kWh
    Lead-acid batteries, all types 70 kWhc
    Lithium-ion batteries 20 kWh
    Nickel-cadmium (Ni-Cd), nickel metal hydride (Ni-MH) and nickel zinc (Ni-Zn) batteries 70 kWh
    Nonelectrochemical ESSd 70 kWh
    Other battery technologies 10 kWh
    Other electrochemical ESS technologies 3 kWh
    Sodium nickel chloride batteries 70 kWh
    Zinc manganese dioxide batteries (Zn-MnO2) 70 kWh
    For SI: 1 kilowatt hour = 3.6 megajoules.
    a. Energy capacity is the total energy capable of being stored (nameplate rating), not the usable energy rating. For units rated in amp-hours, kWh shall equal rated voltage
    times amp-hour rating divided by 1,000.
    b. Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.
    c. Fifty gallons of lead-acid battery electrolyte shall be considered equivalent to 70 kWh.
    d. Covers nonelectrochemical technologies such as flywheel and thermal ESS.    		 For SI: 1 kilowatt hour = 3.6 megajoules.
    a. Energy capacity is the total energy capable of being stored (nameplate rating), not the usable energy rating. For units rated in amp-hours, kWh shall equal rated voltage
    times amp-hour rating divided by 1,000.
    b. Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.
    c. Fifty gallons of lead-acid battery electrolyte shall be considered equivalent to 70 kWh.
    d. Covers nonelectrochemical technologies such as flywheel and thermal ESS.

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    ENERGY SYSTEMS

    1207.1.4 Permits. Permits shall be obtained for ESS as follows:

    1. Construction permits shall be obtained for stationary ESS installations and for mobile ESS charging and storage installations covered by Section 1207.10.1. Permits shall be obtained in accordance with Section 105.6.6.
    2. Operational permits shall be obtained for stationary ESS installations and for mobile ESS deployment operations covered by Section 1207.10.3. Permits shall be obtained in accordance with Section 105.5.14.

    1207.1.4.1 Communication utilities. Operational permits shall not be required for lead-acid and nickel-cadmium battery systems at facilities under the exclusive control of communications utilities that comply with NFPA 76 and operate at less than 50 voltage alternating current (VAC) and 60 voltage direct current (VDC).

    1207.1.5 Construction documents. The following information shall be provided with the permit application:

    1. Location and layout diagram of the room or area in which the ESS is to be installed.
    2. Details on the hourly fire-resistance ratings of assemblies enclosing the ESS.
    3. The quantities and types of ESS to be installed.
    4. Manufacturer’s specifications, ratings and listings of each ESS.
  • CFC § 12-10 High relevance — show source text

    Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.
    c. Fifty gallons of lead-acid battery electrolyte shall be considered equivalent to 70 kWh.
    d. Covers nonelectrochemical technologies such as flywheel and thermal ESS.|

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    ENERGY SYSTEMS

    1207.1.4 Permits. Permits shall be obtained for ESS as follows:

    1. Construction permits shall be obtained for stationary ESS installations and for mobile ESS charging and storage installations covered by Section 1207.10.1. Permits shall be obtained in accordance with Section 105.6.6.
    2. Operational permits shall be obtained for stationary ESS installations and for mobile ESS deployment operations covered by Section 1207.10.3. Permits shall be obtained in accordance with Section 105.5.14.

    1207.1.4.1 Communication utilities. Operational permits shall not be required for lead-acid and nickel-cadmium battery systems at facilities under the exclusive control of communications utilities that comply with NFPA 76 and operate at less than 50 voltage alternating current (VAC) and 60 voltage direct current (VDC).

    1207.1.5 Construction documents. The following information shall be provided with the permit application:

    1. Location and layout diagram of the room or area in which the ESS is to be installed.
    2. Details on the hourly fire-resistance ratings of assemblies enclosing the ESS.
    3. 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.
  • CFC § 12-9 High relevance — show source text

    2025 CALIFORNIA FIRE CODE 12-9

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

    ENERGY SYSTEMS

    1206.8 Outdoor installation. Stationary fuel cell power systems located outdoors shall be separated by not less than 5 feet (1524 mm) from the following:

    1. Lot lines.

    2. Public ways.

    3. Buildings.

    4. Stored combustible materials.

    5. Hazardous materials.

    6. High-piled stock.

    7. Any portion of a designated means of egress system.

    8. Other exposure hazards.

    1206.9 Fuel supply. The design, location and installation of the fuel supply for stationary fuel cell power systems shall comply with Chapter 53, Chapter 58 and the International Fuel Gas Code, based on the particular fuel being supplied to the system.

    1206.10 Manual shutoff. Access to a manual shutoff valve shall be provided for the fuel piping within 6 feet (1829 mm) of any fuel storage tank serving the fuel cell and within 6 feet (1829 mm) of the power system. If the fuel tank and the stationary fuel cell power system are less than 12 feet (3658 mm) apart, a single shutoff valve shall be permitted. If the stationary fuel cell power system is located indoors, the shutoff valve shall be located outside of the room in which the system is installed, unless otherwise approved by the fire code official.

    1206.11 Ventilation and exhaust. Ventilation and exhaust for stationary fuel cell power systems shall be provided in accordance with NFPA 853.

    1206.12 Fire protection. Fire protection systems for stationary fuel cell power system installations shall be provided in accordance with NFPA 853.

    1206.13 Group R-3 and R-4 fuel cell vehicle energy storage system use. The temporary use of the dwelling unit owner or occupant’s fuel cell-powered electric vehicle to power a Group R-3 or R-4 dwelling while parked in an attached or detached garage or outside shall comply with the vehicle manufacturer’s instructions and the California Electrical Code .

    SECTION 1207—ELECTRICAL ENERGY STORAGE SYSTEMS (ESS)

    1207.1 General. The provisions in this section are applicable to stationary and mobile electrical energy storage systems (ESS).

    Exception: ESS in Group R-3 and R-4 occupancies shall only be required to comply with Section 1207.11 except where Section 1207.11.4 requires compliance with Sections 1207.1 through 1207.9.

    1207.1.1 Utilities and industrial applications. This section shall not apply to capacitors and capacitor equipment for electric utilities and industrial facilities used in applications such as flexible AC transmission (FACTS) devices, filter capacitor banks, power factor correction, and standalone capacitor banks for voltage correction and stabilization. (Material based on NFPA 855 2023 Ed.)

    1207.1.2 Mobile ESS. Mobile ESS deployed at an electric utility substation or generation facility for 90 days or less shall not add to the threshold values in Table 1207.1.3 for the stationary ESS installation if both of the following conditions apply:

    1. The mobile ESS complies with Section 1207.10.
    2. The mobile ESS is being used only during periods in which the facility’s stationary ESS is being tested, repaired, retrofitted or replaced. (Material based on NFPA 855 2023 Ed.)
  • 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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    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.)

  • 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 .

Frequently asked questions

Do deployed mobile ESS always need an operational permit?

Yes. Operational permits are required for mobile ESS deployments per § 1207.10.3 and § 1207.1.4; construction permits are required for charging/storage locations.

If I deploy a mobile ESS for 45 days at a community event, do I need to treat it like a permanent installation?

Deployments longer than 30 days must comply with the charging/storage (permanent) rules in § 1207.10.6 or obtain additional permits to extend operations up to 180 days as allowed; temporary deployments ≤30 days follow the deployed‑unit rules in § 1207.10.7. file

Can I hard‑wire a mobile ESS into site electrical systems when deployed?

No. Fixed electrical wiring shall not be provided for deployed mobile ESS; electrical connections must follow the manufacturer/UL 9540 listing and use temporary wiring in accordance with the California Electrical Code (§ 1207.10.7.4).

Do mobile ESS at utility substations count toward Table 1207.1.3 thresholds?

Not if the mobile ESS is deployed at an electric utility substation or generation facility for 90 days or less, complies with § 1207.10, and is used only while the facility’s stationary ESS is being tested, repaired, retrofitted or replaced (see § 1207.1.2).

What is the minimum separation from public seating or tents?

Deployed mobile ESS must be at least 50 feet from public seating areas and from tents, canopies and membrane structures with an occupant load of 30 or more (§ 1207.10.7.3).

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