Chapter 3 — GENERAL REGULATIONS
304.4 Appliances in Attics and Under-Floor Spaces.
California Mechanical Code (Title 24, Part 4) · 2022 edition · updated 2026-09-10 · California
Italicized text is a California amendment to the model code, as printed in the official publication.
An attic or under-floor space in which an appliance is installed shall be accessible through an opening and passageway not less than the largest component of the appliance, and not less than 22 inches by 30 inches (559 mm by 762 mm).
304.4.1 Length of Passageway. Where the height of the passageway is less than 6 feet (1829 mm), the distance from the passageway access to the appliance shall not exceed 20 feet (6096 mm) measured along the centerline of the passageway. [NFPA 54:9.5.1.1] 304.4.2 Width of Passageway. The passageway shall be unobstructed and shall have solid flooring not less than 24 inches (610 mm) wide from the entrance opening to the appliance. [NFPA 54:9.5.1.2] 304.4.3 Work Platform. A level working platform not less than 30 inches by 30 inches (762 mm by 762 mm) shall be provided in front of the service side of the appliance. [NFPA 54:9.5.2] Exception: A working platform need not be provided where the furnace is capable of being serviced from the required access opening. The furnace service side shall not exceed 12 inches (305 mm) from the access opening. 304.4.4 Lighting and Convenience Outlet. A permanent 120 V receptacle outlet and a luminaire shall be installed near the appliance. The switch controlling the luminaire shall be located at the entrance to the passageway. {NFPA 54:9.5.3}
50 2022 CALIFORNIA MECHANICAL CODE
GENERAL REGULATIONS
are intended to breakaway under flood loads in accordance with the building code. 305.3.2 Air Exhaust and Intake Openings. Outside air exhaust openings and air intake openings shall be located at or above the elevation required by the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher.
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Ask AI about this code▸Contents — California Mechanical Code (Title 24, Part 4)
- Chapter 1 — GENERAL CODE PROVISIONS
- Chapter 2 — DEFINITIONS
▸Chapter 3 — GENERAL REGULATIONS
Overview- 301.1 Applicability. This chapter covers general requirements …
- 301.2 Approval. Equipment or appliance shall be approved
- 301.3 Design of Equipment. The installer or contractor
- 301.4 Electrical Connections. For equipment regulated
- 301.5 Oil-Burning Appliances. The tank, piping, and
- 301.6 Personnel Protection. A metal guard shall be provided ar…
- 301.7 OSHPD 1R [OSHPD 1R]. For OSHPD 1R, refer to
- 302.1 Minimum Standards. Listed pipe, pipe fittings,
- 302.2 Alternate Materials and Methods of Construc-
- 302.3 Alternative Engineered Design. An alternative
- 303.1 Listed Appliances. The installation of equipment
- 303.2 Closet or Alcove Installations. [Not adopted
- 303.3 Unlisted Appliances. Except as otherwise permitted in th…
- 303.4 Anchorage of Appliances. Appliances designed to
- 303.5 Movement. Movement of appliances with casters
- 303.6 Identification of Equipment. Where more than one
- 303.7 Liquefied Petroleum Gas Facilities. Containers,
- 303.8 Appliances on Roofs. Appliances on roofs shall be
- 303.9 Avoiding Strain on Gas Piping. Appliances shall
- 303.10 Clearances. Appliances and their vent connectors
- 303.11 Installation in Commercial Garages. Appliances installe…
- 303.12 Installation in Aircraft Hangars. Heaters in aircraft h…
- 304.1 General. All appliances shall be located with respect
- 304.2 Sloped Roof. Where equipment or appliances that
- 304.3 Access to Appliances on Roofs. Appliances
- 304.4 Appliances in Attics and Under-Floor Spaces.
- 305.4 Elevator Shaft. Unless required for the functionality
- 305.5 Drainage Pan. Where a water heater is located in an
- 306.1 General. Heating appliances shall be equipped with
- 306.2 Building Automation Systems. [OSHPD 1]
- 305.1 Installation in Residential Garages. Appliances
- 305.2 Pit Location. Where excavation is necessary to
- 305.3 Flood Hazard Areas. For buildings located in flood
- 307.1 Fuel-Burning Appliances. Fuel-burning heating
- 307.2 Electric Heating Appliances. Electric heating
- 307.3 Heat Pump and Electric Cooling Appliances.
- 307.4 Absorption Units. Absorption units shall bear a permanen…
- 308.1 General. Piping or equipment shall not be so located as
- 309.1 Engineering Practices. Design, construction, and
- 309.2 Concealing Imperfections. It shall be unlawful to
- 309.3 Installation Practices. Mechanical systems shall
- 310.1 Condensate Disposal. Condensate from air washers, air-co…
- 310.2 Condensate Control. Where any equipment or
- 310.3 Condensate Waste Pipe Material and Sizing.
- 310.4 Appliance Condensate Drains. Condensate drain
- 310.5 Point of Discharge. Air-conditioning condensate
- 310.6 Condensate Waste From Air-Conditioning
- 310.7 Plastic Fittings. Female plastic screwed fittings shall
- 311.1 Source. A heating or cooling air system shall be provide…
- 313.7 Gas Piping. Gas piping shall be supported by metal
- 311.2 Air Filters. Air filters shall be installed in a heating,
- 311.3 Prohibited Source. Outside or return air for a heating o…
- 311.4 Return-Air Limitations. Return air from one
- 311.5 California Energy Code Requirements for Res-
- 312.1 General. Water supply, sanitary drainage, and backflow p…
- 313.1 General. Piping, tubing, appliances, and appurtenances s…
- 313.2 Material. Hangers and anchors shall be of sufficient
- 313.3 Suspended Piping. Suspended piping or tubing
- 313.4 Alignment. Piping or tubing shall be supported in
- 313.5 Underground Installation. Piping or tubing in the
- 313.6 Hanger Rod Sizes. Hanger rod sizes shall be not
- 314.1 General. Heating, ventilating, and air-conditioning
- 315.1 General. Louvers located in areas within hurricaneprone …
- 316.1 General. Piping or tubing passing under or through
- 316.2 Installation. Piping or tubing shall be installed so that
- 316.3 Corrosion, Erosion, and Mechanical Damage.
- 316.4 Protectively Coated Pipe. Protectively coated pipe
- 316.5 Fire-Resistant Construction. Piping, tubing, and
- 316.6 Steel Nail Plates. Plastic piping or tubing, copper
- 316.7 Sleeves. Sleeves shall be provided to protect piping
- 316.8 Firewalls. A pipe sleeve through a firewall shall have
- 316.9 Structural Members. A structural member weakened or impa…
- 316.10 Rodentproofing. Mechanical system shall be constructed …
- 316.11 Metal Collars. In or on buildings where openings
- 317.1 Trenches. Trenches deeper than the footings of a
- 317.2 Tunneling and Driving. Tunneling and driving shall
- 317.3 Open Trenches. Excavations required to be made for
- 317.4 Excavations. Excavations shall be completely backfilled …
- 318.1 Applicability. This part is applicable to health facil-
- 318.2 Services/Systems and Utilities. Refer to Section
- 319.1 Requirements for Hospitals and Optional Serv-
- 319.2 Requirements for Skilled Nursing, Intermedi-
- 320.1 Requirements for Hospitals and Optional Serv-
- 320.2 Requirements for Skilled Nursing, Intermedi-
- 320.3 Requirements for Outpatient Facilities and
- 320.4 Telephone and Technology Equipment Centers.
- 320.5 Psychiatric Services. [OSHPD 1, 1R, 2, 4 & 5] For
- 321.1 (Does not apply to OSHPD 3 surgical clinic.) All heat-
- 321.2 All heating equipment and fans necessary to maintain
- 321.3 Equipment necessary for humidification of the areas
- 321.4 All supply, return, and exhaust fans required to maintain
- 321.5 All control components and control systems necessary
- 321.6 Alarms for airborne infection isolation rooms and pro-
- 322.1 The following conditions shall be met for sensitive
- 323.0 Mechanical Equipment Schedules. [OSHPD 1,
- Chapter 4 — VENTILATION AIR
- Chapter 5 — EXHAUST SYSTEMS
- Chapter 6 — DUCT SYSTEMS
- Chapter 7 — COMBUSTION AIR
- Chapter 8 — CHIMNEYS AND VENTS
- Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
- Chapter 10 — BOILERS AND PRESSURE VESSELS
- Chapter 11 — REFRIGERATION
- Chapter 12 — HYDRONICS
- Chapter 13 — FUEL GAS PIPING
- Chapter 14 — PROCESS PIPING
- Chapter 15 — SOLAR ENERGY SYSTEMS
- Chapter 16 — STATIONARY POWER PLANTS
- Chapter 17 — REFERENCED STANDARDS
- Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
- Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
- Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
- Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
- Appendix E — SUSTAINABLE PRACTICES
- Appendix F — GEOTHERMAL ENERGY SYSTEMS
- Appendix G — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
- Appendix H — EXAMPLE CALCULATION OF OUTDOOR AIR RATE