CRSC · California Referenced Standards Code

What additional shielding and control‑station rules apply above 50 kVp?

If a therapeutic x‑ray system can operate above 50 kVp, California code requires the control booth be fixed to the building and let the operator see the patient from behind shielding—either with a window that provides the same attenuation as the adjacent wall, or with mirrors or CCTV—so the operator never leaves the protected position during exposure (see § 3104C.2) .

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

Equipment that operates above 50 kVp must provide a control station that is physically secured to the building and that allows the operator to see the patient from behind a protected barrier during exposures. The control‑station shielding must be either an integral part of the building or anchored to the building, and the control‑station must include a window with radiation attenuation equal to the adjacent barrier, a mirror system, or a closed‑circuit television viewing screen so the patient is visible without leaving the protected area, per § 3104C.2 .

The single most important rule: if the therapeutic x‑ray unit can run above 50 kVp, the control station must be fixed to the building and must let the operator observe the patient from behind shielding that provides the same attenuation as the surrounding barrier (or use mirrors/CCTV) — § 3104C.2 .

Requirements in detail

1) Physical anchoring / permanence of control station

  • Requirement: the control station shielding must be an integral part of the building or anchored to the building (fixed, not a free‑standing/unsecured shield). This is a mandatory condition for equipment > 50 kVp under § 3104C.2(1) .
  • Why it matters: anchoring prevents movement or misalignment of the protective barrier that could compromise shielding during operation.

2) Visibility and protective window / alternative viewing systems

  • Requirement: the control station must provide direct observation of the patient without the operator leaving the protected area by supplying one of the following:
    • a window whose radiation attenuation equals the required attenuation of the adjacent barrier, or
    • a mirror system, or
    • a closed‑circuit television (CCTV) viewing screen, per § 3104C.2(2) .
  • Note: when an observation window is used elsewhere in this chapter, the code also clarifies that the window must provide attenuation equal to the surrounding barrier (see § 3103C.2) .

Decision‑relevant dimensions / values (quick reference)

Decision item What the code requires Where to find the rule Code Reference
Threshold voltage Applies when equipment operates above 50 kVp Controls which rules apply § 3104C.2
Control‑station permanence Must be integral to building or anchored to building Prevents unsecured movable shields § 3104C.2(1)
Observation method Window (equal attenuation), mirror, or CCTV; patient visible without leaving protected area Ensures operator observation from shielded position § 3104C.2(2)
Window attenuation basis Window attenuation must equal adjacent barrier attenuation See definition and parallel requirement for windows § 3104C.2(2) and § 3103C.2
Barrier design calculations All shielding barriers must meet Section 12‑31C‑101 (Referenced Standards Code) Use referenced standards for thickness/attenuation calculations § 3102C

How to interpret “attenuation equal to the adjacent barrier”

  • The code requires that an observation window provide the same radiation attenuation as the surrounding barrier; in practice the window assembly must be designed so the net transmitted radiation through the window is no greater than that through the adjacent wall/floor/ceiling (see § 3104C.2(2) and § 3103C.2) .
  • The numeric thickness / material required to achieve that attenuation is calculated using the shielding formulas and tables referenced in the California Referenced Standards Code (Section 12‑31C‑101), which are not reproduced in § 3104C.2 itself .

Exceptions & special cases

  • The text of § 3104C.2 does not list any exceptions to the anchoring or window/visibility requirements for equipment above 50 kVp; it states the two requirements as mandatory for equipment operating above this threshold .
  • Higher‑energy equipment has additional requirements: for equipment operating above 150 kVp, the code imposes interlocks and control‑station location requirements (see § 3104C.3) .
  • Calculation of barrier thickness / window attenuation is governed by the California Referenced Standards Code (Section 12‑31C‑101); those calculation tables and procedures must be used to size barriers and windows. The detailed numeric attenuation values are not contained in § 3104C.2 itself and must be taken from the referenced standards .

Common mistakes

  • Installing a free‑standing, unanchored control booth or shield and treating it as compliant — § 3104C.2(1) requires the control station to be integral or anchored to the building .
  • Using an observation window that looks thick but hasn’t been specified to provide the same attenuation as the adjacent barrier; visual similarity is not compliance — the window must be shown to equal the adjacent barrier’s attenuation per § 3104C.2(2) and § 3103C.2 .
  • Assuming a plain glass window is acceptable without calculation or manufacturer certification; the assembly must meet the required attenuation.
  • Forgetting the visibility requirement: the operator must be able to observe and communicate with the patient without leaving the protected position during exposure — an administrative or procedural workaround is not a substitute for the design requirement in § 3104C.2(2) .

Worked example — concrete scenario

Scenario: A radiation therapy room will house a unit that routinely operates at 100 kVp.

Step 1 — Does § 3104C.2 apply?

  • Yes — the unit operates above 50 kVp, so the § 3104C.2 requirements apply .

Step 2 — Control station anchoring

  • Design the control station so the shielding is built into the room (integral), or attach and anchor a protective booth to the building structure (bolted to floor/wall/ceiling). This satisfies § 3104C.2(1) .

Step 3 — Observation provision

  • Provide one of: (a) an observation window, (b) a mirror system, or (c) CCTV. If you choose a window, the window assembly must be designed to provide radiation attenuation equal to the adjacent barrier (wall) per § 3104C.2(2) .
  • How to size the window: use the shielding design procedures and tables found in the California Referenced Standards Code (Section 12‑31C‑101). Because § 3104C.2 itself does not give numeric thicknesses, the project must run the attenuation calculation per the referenced standards and specify a certified radiation window panel whose rated attenuation equals the adjacent barrier .

Step 4 — Verification at final inspection

  • Provide calculations and product data showing the control window (or mirror/CCTV system) meets the required attenuation equivalence and that the control station is anchored/integral. If using CCTV, provide assurance that the system provides continuous visibility during exposures as required by § 3104C.2(2) .

If you need numeric example calculations (e.g., mm lead or lead‑glass thickness for a specific workload, distance, and occupancy), those require the shielding methodology and numeric tables in Section 12‑31C‑101 (Referenced Standards Code); that section was not included here, so numeric sizing cannot be derived from § 3104C.2 alone .

Related provisions

  • § 3101C — Definitions (Primary/Secondary protective barrier; Useful beam) — foundational terms used in Chapter 31C .
  • § 3102C — Radiation shielding barriers must meet Section 12‑31C‑101 (Referenced Standards Code) — use this for attenuation calculations and barrier sizing .
  • § 3103C.1 — Operator station for radiographic installations (protective barrier, protected booth) — related visibility/shielding language .
  • § 3103C.2 — Observation window must provide attenuation equal to surrounding barrier — analogous requirement referenced by § 3104C.2(2) .
  • § 3104C.1 — Primary protective barrier requirement for areas struck by the useful beam (general requirement for therapy rooms) .
  • § 3104C.3 — Additional requirements for equipment operating above 150 kVp (interlocks, control‑station location) — higher‑energy controls beyond § 3104C.2 .
  • § 3104C.4 — Auxiliary door opening means where power doors are only access — ancillary requirement for therapy rooms .
  • § 3104C.5 — Warning light requirement for equipment above 500 kVp — additional high‑energy requirement .

Code references

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

  • CRSC § 3103C.1 High relevance — show source text

    SECTION 3103C—MEDICAL RADIOGRAPHIC AND PHOTOFLUOROGRAPHIC INSTALLATIONS

    3103C.1 Operator station. The operator’s station at the control shall be behind a protective barrier either in a separate room, in a protected booth or behind a shield which will intercept the useful beam and any radiation which has been scattered only once.

    3103C.2 Patient observation and communication. Provision shall be made for the operator to observe and communicate with the patient without leaving the shielded position at the control panel. When an observation window is used, it must provide radiation atten- uation equal to that required in the surrounding barrier.

    SECTION 3104C—MEDICAL THERAPEUTIC X-RAY INSTALLATIONS

    3104C.1 General. All wall, floor and ceiling areas that can be struck by the useful beam, plus a border of 1 foot (305 mm), shall be provided with primary protective barriers.

    3104C.2 Equipment operating above 50 kVp. Equipment operating above 50 kVp shall conform with the following: 1. The control station shielding shall either be an integral part of the building or anchored to the building. 2. The control station shall be provided with a window having radiation attenuation equal to that required by the adjacent barrier, or a mirror system, or a closed-circuit television viewing screen. The patient area must be visible to the operator with- out having to leave the protected area during exposure.

    3104C.3 Equipment operating above 150 kVp. Equipment operating above 150 kVp shall conform to the following: 1. The treatment room shall be provided with interlocks so that when any door of the treatment room is opened, either the machine will shut off automatically or the radiation level within the room will be reduced to an average of not more than 2 milliroentgens per hour and a maximum of 10 milliroentgens per hour at a distance of one meter in any direction from the target. After such shutoff or reduction in output, it shall be possible to restore the machine to full operation only from the control panel. 2. The control station shall be within a protective booth or in an adjacent room.

    3104C.4 A minimum of one door shall be provided with an auxiliary means for being opened in case of power failure or mechanical breakdown, where large power-driven doors offer the only access to the room.

    3104C.5 A flashing red warning signal light energized only when the useful beam is on shall be located adjacent to the entrance(s) to a therapy room with equipment capable of operating above 500 kVp.

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    31C-4 2025 CALIFORNIA BUILDING CODE

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    CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 31D – FOOD ESTABLISHMENTS

    (Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  • CRSC § 1.11. High relevance — show source text

    The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

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    31C-2 2025 CALIFORNIA BUILDING CODE

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    31C [DPH] RADIATION

    SECTION 3101C—SCOPE

    For the purpose of this chapter, the following terms shall have the meaning indicated:

    PRIMARY PROTECTIVE BARRIER is a barrier to attenuate the useful beam.

    SECONDARY PROTECTIVE BARRIER is a barrier to attenuate stray radiation.

    STRAY RADIATION is radiation not serving any useful purpose, which includes leakage and scattered radiation.

    USEFUL BEAM is the radiation which passes through the window, aperture, cone or other collimating device of the tube housing.

    SECTION 3102C—RADIATION SHIELDING BARRIERS

    All radiation shielding barriers in rooms and enclosures housing machines shall meet the requirements of Section 12-31C-101, Chapter 12-31C, Part 12, California Referenced Standards Code. The Department of Health Services is the only agency that may grant a variance or exception to these standards.

    SECTION 3103C—MEDICAL RADIOGRAPHIC AND PHOTOFLUOROGRAPHIC INSTALLATIONS

    3103C.1 Operator station. The operator’s station at the control shall be behind a protective barrier either in a separate room, in a protected booth or behind a shield which will intercept the useful beam and any radiation which has been scattered only once.

    3103C.2 Patient observation and communication. Provision shall be made for the operator to observe and communicate with the patient without leaving the shielded position at the control panel. When an observation window is used, it must provide radiation atten- uation equal to that required in the surrounding barrier.

    SECTION 3104C—MEDICAL THERAPEUTIC X-RAY INSTALLATIONS

    3104C.1 General. All wall, floor and ceiling areas that can be struck by the useful beam, plus a border of 1 foot (305 mm), shall be provided with primary protective barriers.

    3104C.2 Equipment operating above 50 kVp. Equipment operating above 50 kVp shall conform with the following: 1. The control station shielding shall either be an integral part of the building or anchored to the building. 2. The control station shall be provided with a window having radiation attenuation equal to that required by the adjacent barrier, or a mirror system, or a closed-circuit television viewing screen. The patient area must be visible to the operator with- out having to leave the protected area during exposure.

  • CRSC § 506.11.6 High relevance — show source text

    506.11.6 Reduced Clearance with Air Gaps. When using clearance reduction systems that include an air gap between the combustible surface and the selected means of protection, air circulation shall be provided by one of the methods in Section 506.11.6.1 through Section 506.11.6.3. [NFPA 91:4.7.4.7]

    506.11.6.1 Air Circulation. Air circulation shall be permitted to be provided by leaving all edges of the protecting system open with at least a 1 inch (25.4 mm) air gap. [NFPA 91:4.7.4.7.1] 506.11.6.2 Single Flat Wall. If the means of protection is mounted on a single flat wall away from corners, air circulation shall be permitted to be provided by one of the following:

    (1) Leaving only the top and bottom edges open to circulation by maintaining the 1 inch (25.4 mm) air gap.

    (2) Leaving the top and both side edges open to circulation by maintaining the 1 inch (25.4 mm) air gap. [NFPA 91:4.7.4.7.2] 506.11.6.3 Thermal Shielding. Thermal shielding that covers two walls in a corner shall be permitted to be open at the top and bottom edges with at least 1 inch (25.4 mm) air gap. [NFPA 91:4.7.4.7.3]

    TABLE 506.11

    REDUCTION OF DUCT CLEARANCE WITH SPECIFIED FORMS OF PROTECTION

    [NFPA 91: TABLE 4.7.4]

    FORM OF PROTECTION* MAXIMUM ALLOWABLE REDUCTION IN CLEARANCE (percent) Col3
    FORM OF PROTECTION* AS WALL PROTECTOR OR
    VERTICAL SURFACE    		 AS CEILING PROTECTOR OR
    HORIZONTAL SURFACE
    31⁄2 inch thick masonry wall without ventilated air space 33 None
    1⁄2 inch thick noncombustible insulation board over 1 inch glass fiber or min-
    eral wool batts without ventilated air space    		 50 33
    0.024 inch (24 gauge) sheet metal over 1 inch glass fiber or mineral wool batts
    reinforced with wire, or equivalent on rear face with at least a 1 inch air gap    		 66 66
    31⁄2 inch (90 mm) thick masonry wall with at least a 1 inch air gap 66 None
    0.024 inch (24 gauge) sheet metal with at least a 1 inch air gap 66 50
    1⁄2 inch thick noncombustible insulation board with at least a 1 inch air gap 66 50
    0.024 inch (24 gauge) sheet metal with ventilated air space over at least
    0.024 inch (24 gauge) sheet metal with at least a 1 inch air gap    		 66 50
    1 inch glass fiber or mineral wool batts sandwiched between two sheets of
    0.024 inch (24 gauge) sheet metal with at least a 1 inch air gap    		 66 50

    For SI units: 1 inch = 25.4 mm

    • Clearance reduction applied to and covering all combustible surfaces within the distance specified as required clearance with no protection in Table 506.10.4.

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  • CRSC § 5.5 High relevance — show source text

    5.5|Yesc|Yes| |Fire-resistance-rated separations|1207.7.4|Yes|Yes| |General installation requirements|1207.4|Yes|Yes| |Maximum allowable quantities|1207.5.2|No|Yes| |Size and separation|1207.5.1|Yes|Yes| |Smoke and automatic fire detectione|1207.5.4|Yesd|Yes| |Technology specific protection|1207.6|Yes|Yes| |NA = Not Allowed.
    a. See Section 1207.7.1.
    b. See Section 1207.7.2.
    c. Where approved by the fire code official, fire suppression systems are permitted to be omitted in dedicated-use buildings located more than 100 feet (30.5 m) from buildings,
    lot lines, public ways, stored combustible materials, hazardous materials, high-piled stock and other exposure hazards.
    d. Where approved by the fire code official, alarm signals are not required to be transmitted to a central station, proprietary or remote station service in accordance with NFPA
    72, or a constantly attended location where local fire alarm annunciation is provided and trained personnel are always present.
    e. Lead-acid and nickel-cadmium battery systems installed in Group U buildings and structures less than 1,500 square feet (139 m2) under the exclusive control of communi-
    cations utilities, and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76, are not required to have an approved automatic smoke or fire detection
    system.|NA = Not Allowed.
    a. See Section 1207.7.1.
    b. See Section 1207.7.2.
    c. Where approved by the fire code official, fire suppression systems are permitted to be omitted in dedicated-use buildings located more than 100 feet (30.5 m) from buildings,
    lot lines, public ways, stored combustible materials, hazardous materials, high-piled stock and other exposure hazards.
    d. Where approved by the fire code official, alarm signals are not required to be transmitted to a central station, proprietary or remote station service in accordance with NFPA
    72, or a constantly attended location where local fire alarm annunciation is provided and trained personnel are always present.
    e. Lead-acid and nickel-cadmium battery systems installed in Group U buildings and structures less than 1,500 square feet (139 m2) under the exclusive control of communi-
    cations utilities, and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76, are not required to have an approved automatic smoke or fire detection
    system.|NA = Not Allowed.
    a. See Section 1207.7.1.
    b. See Section 1207.7.2.
    c. Where approved by the fire code official, fire suppression systems are permitted to be omitted in dedicated-use buildings located more than 100 feet (30.5 m) from buildings,
    lot lines, public ways, stored combustible materials, hazardous materials, high-piled stock and other exposure hazards.
    d. Where approved by the fire code official, alarm signals are not required to be transmitted to a central station, proprietary or remote station service in accordance with NFPA
    72, or a constantly attended location where local fire alarm annunciation is provided and trained personnel are always present.
    e.

  • CRSC § 110.8 High relevance — show source text
    1. Insulation installation must:

    A. Be covered with a solid guard that protects against damage from ultraviolet radiation, moisture, landscaping operation, equipment maintenance and wind; and B. Include a rigid plate, which penetrates the slab and blocks the insulation from acting as a conduit for insects from the ground to the structure above the foundation.

    TABLE 110.8-A—SLAB INSULATION REQUIREMENTS FOR HEATED SLAB-ON-GRADE Col2 Col3 Col4 Col5
    INSULATION
    LOCATION    		 INSULATION
    ORIENTATIO
    N    		 INSTALLATION REQUIREMENTS CLIMATE
    ZONE    		 INSULATION
    R-VALUE
    Outside edge of
    heated slab,
    either inside or
    outside the
    foundation wall    		 Vertical From the level of the top of the slab, down 16 inches or to the frost line,
    whichever is greater. Insulation may stop at the top of the footing where this
    is less than the required depth. For below grade slabs, vertical insulation shall
    be extended from the top of the foundation wall to the bottom of the
    foundation (or the top of the footing) or to the frost line, whichever is greater.    		 1–15 5
    Outside edge of
    heated slab,
    either inside or
    outside the
    foundation wall    		 Vertical From the level of the top of the slab, down 16 inches or to the frost line,
    whichever is greater. Insulation may stop at the top of the footing where this
    is less than the required depth. For below grade slabs, vertical insulation shall
    be extended from the top of the foundation wall to the bottom of the
    foundation (or the top of the footing) or to the frost line, whichever is greater.    		 16 10
    Between heated
    slab and outside
    foundation wall    		 Vertical and
    horizontal    		 Vertical insulation from top of slab at inside edge of outside wall down to
    the top of the horizontal insulation. Horizontal insulation from the outside
    edge of the vertical insulation extending 4 feet toward the center of the slab
    in a direction normal to the outside of the building in plan view.    		 1–15 5
    Between heated
    slab and outside
    foundation wall    		 Vertical and
    horizontal    		 Vertical insulation from top of slab at inside edge of outside wall down to
    the top of the horizontal insulation. Horizontal insulation from the outside
    edge of the vertical insulation extending 4 feet toward the center of the slab
    in a direction normal to the outside of the building in plan view.    		 16 10 vertical
    and
    7 horizontal

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    ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

    (h) Wet insulation systems. When insulation is installed on roofs above the roofing membrane or layer used to seal the roof from water penetration, the effective R -value of the insulation shall be as specified in Reference Joint Appendix JA4.

  • CRSC § 1207.7.1. High relevance — show source text

    See Section 1207.7.1.
    b. See Section 1207.7.2.
    c. Where approved by the fire code official, fire suppression systems are permitted to be omitted in dedicated-use buildings located more than 100 feet (30.5 m) from buildings,
    lot lines, public ways, stored combustible materials, hazardous materials, high-piled stock and other exposure hazards.
    d. Where approved by the fire code official, alarm signals are not required to be transmitted to a central station, proprietary or remote station service in accordance with NFPA
    72, or a constantly attended location where local fire alarm annunciation is provided and trained personnel are always present.
    e. Lead-acid and nickel-cadmium battery systems installed in Group U buildings and structures less than 1,500 square feet (139 m2) under the exclusive control of communi-
    cations utilities, and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76, are not required to have an approved automatic smoke or fire detection
    system.|NA = Not Allowed.
    a. See Section 1207.7.1.
    b. See Section 1207.7.2.
    c. Where approved by the fire code official, fire suppression systems are permitted to be omitted in dedicated-use buildings located more than 100 feet (30.5 m) from buildings,
    lot lines, public ways, stored combustible materials, hazardous materials, high-piled stock and other exposure hazards.
    d. Where approved by the fire code official, alarm signals are not required to be transmitted to a central station, proprietary or remote station service in accordance with NFPA
    72, or a constantly attended location where local fire alarm annunciation is provided and trained personnel are always present.
    e. Lead-acid and nickel-cadmium battery systems installed in Group U buildings and structures less than 1,500 square feet (139 m2) under the exclusive control of communi-
    cations utilities, and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76, are not required to have an approved automatic smoke or fire detection
    system.|NA = Not Allowed.
    a. See Section 1207.7.1.
    b. See Section 1207.7.2.
    c. Where approved by the fire code official, fire suppression systems are permitted to be omitted in dedicated-use buildings located more than 100 feet (30.5 m) from buildings,
    lot lines, public ways, stored combustible materials, hazardous materials, high-piled stock and other exposure hazards.
    d. Where approved by the fire code official, alarm signals are not required to be transmitted to a central station, proprietary or remote station service in accordance with NFPA
    72, or a constantly attended location where local fire alarm annunciation is provided and trained personnel are always present.
    e. Lead-acid and nickel-cadmium battery systems installed in Group U buildings and structures less than 1,500 square feet (139 m2) under the exclusive control of communi-
    cations utilities, and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76, are not required to have an approved automatic smoke or fire detection
    system.|

    1207.7.1 Dedicated-use buildings. For the purpose of Table 1207.7, dedicated-use ESS buildings shall be classified as Group F-1 occupancies and comply with all the following:

    1. The building shall only be used for ESS, electrical energy generation and other electrical grid-related operations.
  • CRSC § 1207.6 High relevance — show source text
    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 1207.6.3 Yesa Yesa Yes Yes No Yes Yes Yes
    Safety caps 1207.6.4 Yes Yes No No No No Yes Yes
    Spill control and
    neutralization    		 1207.6.2 Yesc Yesc Yesf No Yes No Yes Yes
    Thermal
    runaway    		 1207.6.5 Yesd Yes Yese Yese No Yes Yese Yes
    a. Not required for lead-acid and nickel-cadmium batteries at facilities under the exclusive control of communications utilities that comply with NFPA 76 and operate at less
    than 50 VAC and 60 VDC.
    b. Protection shall be provided unless documentation acceptable to the fire code official is provided in accordance with Section 104.2.2 that provides justification why the
    protection is not necessary based on the technology used.
    c. Applicable to vented-type (i.e., flooded) nickel-cadmium and lead-acid batteries.
    d. Not required for vented-type (i.e., flooded) batteries.
    e. The thermal runaway protection is permitted to be part of a battery management system that has been evaluated with the battery as part of the evaluation to UL 1973.
    f. Not required for batteries with jelled electrolyte.    		 a. Not required for lead-acid and nickel-cadmium batteries at facilities under the exclusive control of communications utilities that comply with NFPA 76 and operate at less
    than 50 VAC and 60 VDC.
    b. Protection shall be provided unless documentation acceptable to the fire code official is provided in accordance with Section 104.2.2 that provides justification why the
    protection is not necessary based on the technology used.
    c.
  • CRSC § 12-72 Medium relevance — show source text

    1. The testing circuit shall be protected by overcurrent devices having a rating of at least ten times the primary current rating of the transformer. Output terminals of the transformer shall be short-circuited, if such a condition results in less than three times the maximum normal load current being drawn from the secondary. Tests shall be continued until constant temperatures are attained or a burnout occurs. Blowing of the fuse on the primary side of the transformer is not considered to be a failure.

    2. If the circuit designs of a control unit or combination signaling system incorporate a time limit cutout or a mercury tube switch wired into the system circuit in such a manner that a short circuit or a ground fault causes the device to carry current in excess of its maximum normal load, it shall withstand the test specified in Items 5 through 7, without introducing a fire hazard.

    3. The device is to be tested in the control equipment as it is intended to be normally used and in series with a protective fuse of the marked maximum rating indicated by the markings on the control unit. All openings in the enclosure of the control equipment shall be covered with surgical cotton, and the enclosure is to be connected to ground through a fuse of the same rating as the protective fuse mentioned above.

    4. The open circuit voltage of the test circuit is to be within 5 percent of the rated voltage; see Sections 12-72-103 (a), Item 4, and 12-72-103 (c), Item 1, of the control equipment circuit in which the device is installed, except that a higher voltage may be used if agreeable to those concerned. The source of current and the test circuit should have sufficient capacity to deliver 1,000 amperes when the system is short-circuited at the testing terminals.

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    PROTECTIVE SIGNALING SYSTEMS

    1. Ignition of the cotton, or of insulation on circuit conductors, emission of flame or molten metal from the enclosure, blowing of the fuse in the grounding conductor, damage to other parts of the control equipment, or any evidence of a fire hazard is to be deemed as failure. Burnout of pigtail leads or a thermal element, or welding of contacts, is not to be considered as a failure.

    PRINTED WIRING BOARDS

    Sec. 12-72-104.

    (a) General.

    1. These requirements cover printed wiring boards that are intended for use in fire protective signaling equipment. The acceptability of the combination of the printed wiring board and the electric equipment is to be determined by the State Fire Marshal.

    2. Printed wiring boards conforming to ASTM Grade FR-5 when tested in accordance with ASTM Designation D-1867, may be used in protective signaling equipment.

    3. Throughout these requirements, the term “printed wiring” is used to designate a pattern of conductive material formed in a predetermined design on the surface or surfaces of a common insulating base, and intended primarily to provide point to point electrical connections, shielding or to form inductors. The term “printed wiring board” is used to designate the combination of a printed writing pattern and the common insulating base completely processed as far as the printed portion is concerned. The term “printed wiring assembly” is used to designate a printed wiring board on which separate components have been added.

  • CRSC § 1.11. Medium relevance — show source text

    CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 31C – RADIATION

    (Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

    Adopting agency BSC BSC-
    CG    		 SFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC
    Adopting agency BSC BSC-
    CG    		 SFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6
    Adopt entire chapter X
    Adopt entire chapter as
    amended (amended
    sections listed below)
    Adopt only those sections
    that are listed below
    Chapter / Section

    The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

    2025 CALIFORNIA BUILDING CODE 31C-1

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

    31C-2 2025 CALIFORNIA BUILDING CODE

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

    31C [DPH] RADIATION

    SECTION 3101C—SCOPE

    For the purpose of this chapter, the following terms shall have the meaning indicated:

    PRIMARY PROTECTIVE BARRIER is a barrier to attenuate the useful beam.

    SECONDARY PROTECTIVE BARRIER is a barrier to attenuate stray radiation.

    STRAY RADIATION is radiation not serving any useful purpose, which includes leakage and scattered radiation.

    USEFUL BEAM is the radiation which passes through the window, aperture, cone or other collimating device of the tube housing.

    SECTION 3102C—RADIATION SHIELDING BARRIERS

    All radiation shielding barriers in rooms and enclosures housing machines shall meet the requirements of Section 12-31C-101, Chapter 12-31C, Part 12, California Referenced Standards Code. The Department of Health Services is the only agency that may grant a variance or exception to these standards.

    SECTION 3103C—MEDICAL RADIOGRAPHIC AND PHOTOFLUOROGRAPHIC INSTALLATIONS

  • CRSC § 31B-22 Medium relevance — show source text

    3162B Anti-Entrapment Devices and Systems . . . . . . . . . . 31B-22

    CHAPTER 31C RADIATION . . . . . . . . . . . . . . . . . . . . . . . . . .31C-1

    3101C Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31C-3

    3102C Radiation Shielding Barriers . . . . . . . . . . . . . . . . . . . . . 31C-3

    3103C Medical Radiographic and Photofluorographic Installations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31C-3

    3104C Medical Therapeutic X-Ray Installations. . . . . . . . . . 31C-3

    CHAPTER 31D FOOD ESTABLISHMENTS. . . . . . . . . . . . . . .31D-1

    3101D Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31D-3

    3102D Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31D-3

    3103D Buildings and Structures. . . . . . . . . . . . . . . . . . . . . . . . . 31D-3

    CHAPTER 31E RESERVED. . . . . . . . . . . . . . . . . . . . . . . . . . .31E-1

    CHAPTER 31F MARINE OIL TERMINALS . . . . . . . . . . . . . . .31F-1

    3101F Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31F-3

    3102F Audit and Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31F-6

    3103F Structural Loading Criteria . . . . . . . . . . . . . . . . . . . . . 31F-19

    3104F Seismic Analysis and Structural Performance. . . . 31F-34

    3105F Mooring and Berthing Analysis and Design . . . . . . 31F-48

    3106F Geotechnical Hazards and Foundations . . . . . . . . . 31F-55

  • CRSC § 2.95 Medium relevance — show source text

    00|2.95|2.20|1.45|3.00|2.35|1.25|DR| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#8 screw into 33 mil steel or
    thicker|8|3.00|2.55|1.60|0.60|3.00|1.80|DR|DR| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#8 screw into 33 mil steel or
    thicker|12|3.00|1.80|DR|DR|3.00|0.65|DR|DR| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#10 screw into 33 mil steel|6|4.00|3.50|2.70|1.95|4.00|2.90|1.70|0.55| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#10 screw into 33 mil steel|8|4.00|3.10|2.05|1.00|4.00|2.25|0.70|DR| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#10 screw into 33 mil steel|12|4.00|2.25|0.70|DR|3.70|1.05|DR|DR| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#10 screw into 43 mil steel or
    thicker|6|4.00|4.00|4.00|3.60|4.00|4.00|3.45|2.70| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#10 screw into 43 mil steel or
    thicker|8|4.00|4.00|3.70|3.00|4.00|3.85|2.80|1.80| |Cold-formed steel framing
    (minimum penetration of steel
    thickness plus 3 threads)|#10 screw into 43 mil steel or
    thicker|12|4.00|3.85|2.80|1.80|4.00|3.05|1.50|DR| |For SI: 1 inch = 25.4 mm, 1 pound per square foot (psf) = 0.0479 kPa, 1 pound per square inch = 0.00689 MPa.
    DR = design required, o.c. = on center.
    a. Cold-formed steel framing shall be minimum 33 ksi steel for 33 mil and 43 mil steel and 50 ksi steel for 54 mil steel or thicker.
    b. Screws shall comply with the requirements of AISI S240.
    c. Foam sheathing shall have a minimum compressive strength of 15 pounds per square inch in accordance with ASTM C578 or ASTM C1289.|For SI: 1 inch = 25.4 mm, 1 pound per square foot (psf) = 0.0479 kPa, 1 pound per square inch = 0.00689 MPa.
    DR = design required, o.c. = on center.
    a. Cold-formed steel framing shall be minimum 33 ksi steel for 33 mil and 43 mil steel and 50 ksi steel for 54 mil steel or thicker.
    b.

  • CRSC § 3104C.4 Medium relevance — show source text

    3104C.4 A minimum of one door shall be provided with an auxiliary means for being opened in case of power failure or mechanical breakdown, where large power-driven doors offer the only access to the room.

    3104C.5 A flashing red warning signal light energized only when the useful beam is on shall be located adjacent to the entrance(s) to a therapy room with equipment capable of operating above 500 kVp.

    2025 CALIFORNIA BUILDING CODE 31C-3

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

    31C-4 2025 CALIFORNIA BUILDING CODE

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

    CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 31D – FOOD ESTABLISHMENTS

    (Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

    Adopting agency BSC BSC-
    CG    		 SFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC
    Adopting agency BSC BSC-
    CG    		 SFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6
    Adopt entire chapter X X X
    Adopt entire chapter as
    amended (amended
    sections listed below)
    Adopt only those sections
    that are listed below
    Chapter / Section

    The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

    2025 CALIFORNIA BUILDING CODE 31D-1

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

    31D-2 2025 CALIFORNIA BUILDING CODE

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

    31D [DPH] FOOD ESTABLISHMENTS

    SECTION 3101D—SCOPE

    The provisions of this chapter shall apply to the construction of commissaries serving mobile food preparation units.

    SECTION 3102D—DEFINITION

    For the purpose of this chapter, the following term shall have the meaning indicated:

Frequently asked questions

What counts as “anchored to the building” for the control station?

Anchored means the shielding/booth is physically attached to the building structure (for example bolted to wall/floor framing or constructed as part of the room partition). The code language requires the control station shielding be an integral part of the building or anchored to the building (see § 3104C.2(1)) .

Can I use CCTV instead of a lead‑glass observation window?

Yes. § 3104C.2(2) allows a mirror system or closed‑circuit television viewing screen as alternatives to an observation window, provided the patient area is visible to the operator without leaving the protected position .

Do the rules in § 3104C.2 specify specific lead thicknesses?

No. § 3104C.2 requires window attenuation equal to the adjacent barrier but does not give numeric thicknesses. Barrier and window sizing use the shielding methods and tables in Section 12‑31C‑101 (California Referenced Standards Code), which must be consulted for numeric values .

If my unit only operates at 49 kVp sometimes, do these rules apply?

No — the explicit threshold in the section is above 50 kVp. Equipment that does not operate above 50 kVp is not subject to § 3104C.2; however, other applicable requirements and good practice (e.g., operator protection and observation) still apply under the chapter definitions and earlier sections (see § 3101C and § 3103C) file.

Where do I get the calculations to show my window equals the adjacent barrier?

Use the shielding design procedures and tables in Section 12‑31C‑101, Chapter 12‑31C, Part 12, California Referenced Standards Code; § 3102C directs you to that referenced standard for barrier design requirements .

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Related in the CRSC

Are auxiliary doors or warning signals required for very‑high‑energy units?

What primary protective barrier area is required for therapy units?

What interlocks and radiation‑reduction requirements apply above 150 kVp?

Therapeutic X‑ray, megavoltage and accelerator shielding

California Referenced Standards Code