CMC · California Mechanical Code

What does 'Accessible' and 'Accessible, Readily' mean?

In the California Mechanical Code, “Accessible” means you can reach equipment but may first have to remove an access panel or door; “Accessible, Readily” means you can reach it directly with no panel removal. The formal definitions are in **§ 203.0**; equipment sections (for example **§ 1105.3**) show how to meet “readily accessible” in practice.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Mechanical Code defines Accessible and Accessible, Readily in § 203.0. Accessible means equipment can be reached but may first require removal of an access panel, door, or similar obstruction. Accessible, Readily means there is a direct path to the equipment without removing a panel, door, or similar obstruction. See § 203.0 for the definitions.

If you must remove an access panel, the item is “Accessible”; if you can get to it directly (no panel removal), it is “Accessible, Readily” (CMC § 203.0).

Requirements in detail

Key definitions (first mention bolded): Accessible, Accessible, Readily, § 203.0. The definitions are short; the practical effect shows up where the code requires equipment to be accessible or readily accessible (examples below).

Quick decision table — when to call something Accessible vs Accessible, Readily

Decision factor	Value / test	Practical effect	Code Reference
Access path	Requires removal of an access panel, door, or similar obstruction	Classified as Accessible (not “readily”)	§ 203.0
Access path	Direct access (no panel/door removal required)	Classified as Accessible, Readily	§ 203.0
Routine maintenance opening size example	Unobstructed opening/passageway ≥ 36 in wide and 80 in high for compressors (specific equipment requirement)	Demonstrates “readily accessible” in practice when dimensioned openings are provided	§ 1105.3 (applies the accessibility concept)
Illumination/service receptacle requirement for accessible equipment	Permanent luminaires required where equipment is required to be accessible or readily accessible	Confirms expectation of serviceability where accessibility is required	§ 1105.4
Equipment in enclosures (e.g., fans, ducts)	Must be located in “accessible areas of adequate size” to allow service or removal	Shows “accessible” is tied to being able to service/replace equipment	§ 511.1.2.1 / § 511.1.3.2

Notes:

The definition itself is textual and does not contain dimensions — it distinguishes only whether removal of a panel (or similar) is required. For practical dimensions and access-opening rules, look at the equipment-specific sections cited above.

How the short definitions affect design and inspection

If an appliance or valve sits behind a removable panel that must be taken out to reach it, it is Accessible, not Accessible, Readily (definition: § 203.0).
Where the code requires equipment to be “readily accessible” (for example, compressors), that requirement is fulfilled only if the item is reached without removing panels — often implemented with a code-required opening and passageway (see § 1105.3).
“Accessible” may be acceptable for items not required to be “readily” accessible, but maintenance actions that are frequent or urgent are commonly required to be readily accessible by other sections (example: shutoff valves and system controls). See related provisions below.

Exceptions & special cases

The definitions are general — several equipment-specific sections modify how accessibility is implemented. For example, compressors and refrigerant valves have specified minimum unobstructed openings to be considered “readily accessible” for routine maintenance (see § 1105.3).
Some equipment is permitted alternative access (e.g., suspended refrigerant evaporators can use portable access), which changes how “accessible” is achieved even if a permanent opening is not provided (see exceptions in § 1105.3).
Emergency or safety devices (emergency shutoff valves, marked system shutoffs) are expected to be readily accessible in practice; consult the fuel-gas sections for installation and marking requirements. § 1310.11 and related subsections discuss accessibility expectations for gas shutoffs.

Common mistakes

Saying a component is “readily accessible” solely because a removable panel is easy to unfasten. The code requires no necessity to remove a panel for “readily” — if panel removal is required, the item is only Accessible (CMC § 203.0).
Ignoring equipment-specific access dimension rules and treating the definition alone as sufficient; many sections (for example, compressors and rooftop equipment) require specific opening sizes and passageways for the item to be considered “readily accessible” — check those sections.
Failing to provide required illumination or service receptacles where the code mandates them for accessible equipment (see § 1105.4).

Worked example — concrete scenario

Scenario: A rooftop compressor must be serviceable. A design provides a gated rooftop hatch and a 30 in × 30 in removable access panel on the equipment room wall behind which the compressor sits.

Definition test: Because a panel must be removed to reach service points, the compressor (as located) is Accessible but not Accessible, Readily per § 203.0.
Code application: For compressors the code requires an “unobstructed readily accessible opening and passageway not less than 36 inches (914 mm) in width and 80 inches (2032 mm) in height” to be provided and maintained where routine maintenance is required. If the design does not provide that opening/passageway, the installation fails the “readily accessible” requirement in § 1105.3.
Fix: Replace the 30×30 access panel/wall condition with a compliant opening/passageway (≥ 36 in × 80 in) or relocate the equipment so service can be performed without removing a panel. Also add the permanent luminaires and controls required by § 1105.4 if the compressor is required to be accessible/readily accessible.

Related provisions

§ 203.0 — Definitions of Accessible and Accessible, Readily (primary definitions).
§ 1105.3 — Opening and passageway dimensions for compressors and components that require routine maintenance (examples of implementing “readily accessible”).
§ 1105.4 — Illumination and service receptacle requirements where equipment is required to be accessible or readily accessible.
§ 511.1.2.1 — Accessibility expectations for in-line exhaust fans (location in accessible areas of adequate size).
§ 511.1.3.2 — Accessibility expectations for rooftop or within-building fans and drains to readily accessible receptacles.
§ 1310.11 — Accessibility and marking for manual gas shutoff valves (shows safety-critical items expected to be readily accessible).

Code references

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

CMC § 204.0 High relevance — show source text
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203.0
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This 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 1.11.0.

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CHAPTER 2

DEFINITIONS

201.0 General.

201.1 Applicability. For the purpose of this code, the following terms have the meanings indicated in this chapter.

No attempt is made to define ordinary words, which are used in accordance with their established dictionary meanings, except where a word has been used loosely, and it is necessary to define its meaning as used in this code to avoid misunderstanding.

202.0 Definition of Terms.

202.1 General. The definitions of terms are arranged alphabetically according to the first word of the term.

203.0 – A –

Absorption Unit. An absorption refrigeration system that has been factory-assembled and tested prior to its installation.

Accepted Engineering Practice. That which conforms to technical or scientific-based principles, test, or standards that are accepted by the engineering profession.

Access Panel. A closure device used to cover an opening into a duct, an enclosure, equipment, or an appurtenance.

[NFPA 96:3.3.1]

Accessible. Where applied to a device, appliance, or equipment, “accessible” means having access thereto, but which first may require the removal of an access panel, door, or similar obstruction.

Accessible, Readily. Having a direct access without the necessity of removing a panel, door, or similar obstruction.
CMC § 932.3 High relevance — show source text
Evaporative coolers. . . . . . . . . . . . . . . . . . . . . . . . 932.3

Fire and smoke dampers . . . . . . . . . . . . . . . . . . . 606.8

Floor furnace. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 906.9

Fuel gas meters . . . . . . . . . . . . . . . . . 1308.5.1, D 104.2

Fuel gas piping . . . . . . . . . . . . . . . . . . . . . . . 1310.3.3.1

Fuel gas pressure regulators . . . . . . . . . . . . . .1308.6.2,

1310.5.1

Grease filters. . . . . . . . . . . . . . . . . . . . . . . . . . 509.2.3.2

Lapped flanges . . . . . . . . . . . . . . . . . . . . . . . 1308.4.9.6

Motors and fans, exhaust systems . . . . . . . . . . . . 503.1

Refrigeration equipment . . . . . . . . . . . . . . . . . . . 1105.3

ACCESSIBLE

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Easily, definition. . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

Readily, definition . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

ACCESSORY DWELLING UNIT

Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

ADMINISTRATION

California . . . . . . . . . . . . . . . . . . . . Chapter 1, Division I

General . . . . . . . . . . . . . . . . . . . . . Chapter 1 , Division II

AIR

Balancing . . . . . . . . . . . . . 314.0, 403.10, 407.3, 511.3.1,

E 503.3.1, E 503.6.5.3,

E 605.1.5, E 803.2

Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407.4

Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.9

Combustion . . . . . . . . . . . . . . . . . (see Combustion Air)

Dilution . . . . . . . . . . . . . . . . . . . . . . . 203.0, Table 403.7,

701.1, 701.1.1, 701.8, 701.10,
CMC § 1.11.0. High relevance — show source text
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This 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 1.11.0.

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CHAPTER 2

DEFINITIONS

201.0 General.

201.1 Applicability. For the purpose of this code, the following terms have the meanings indicated in this chapter.

No attempt is made to define ordinary words, which are used in accordance with their established dictionary meanings, except where a word has been used loosely, and it is necessary to define its meaning as used in this code to avoid misunderstanding.

202.0 Definition of Terms.

202.1 General. The definitions of terms are arranged alphabetically according to the first word of the term.

203.0 – A –

ABS. Acrylonitrile-butadiene-styrene. Accepted Engineering Practice. That which conforms to technical or scientific-based principles, tests, or standards that are accepted by the engineering profession. Accessible. Where applied to a fixture, connection, appliance, or equipment, “accessible” means having access thereto, but which first may require the removal of an access panel, door, or similar obstruction. Accessible, Readily. Having a direct access without the necessity of removing a panel, door, or similar obstruction. Accessory Dwelling Unit. [HCD 1 & HCD 2] An attached or detached residential dwelling unit that provides complete independent living facilities for one or more per- sons and is located on a lot with a proposed or existing pri- mary residence. Accessory dwelling units shall include permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel as the single-family or mul- tifamily dwelling is or will be situated. (See Government Code Section 65852.2.) Air Break. A physical separation which may be a low inlet into the indirect waste receptor from the fixture, appliance, or device indirectly connected. Air Gap, Drainage. The unobstructed vertical distance through the free atmosphere between the lowest opening from a pipe, plumbing fixture, appliance, or appurtenance conveying waste to the flood-level rim of the receptor. Air Gap, Water Distribution. The unobstructed vertical distance through the free atmosphere between the lowest opening from a pipe or faucet conveying potable water to the flood-level rim of a tank, vat, or fixture.

Alternate Water Source. Nonpotable source of water that includes but not limited to gray water, on-site treated nonpotable water, on-site treated nonpotable gray water, rainwater, and reclaimed (recycled) water. Anchors. See Supports. Anodeless Riser. An assembly of steel-cased plastic pipe used to make the transition between plastic piping installed

underground and metallic piping installed aboveground.

[NFPA 54:3.3.3] **Appliance.
CMC § 1105.3 High relevance — show source text
(1) The addition of a second refrigerant is allowed by the equipment manufacturer and is in accordance with the manufacturer’s instructions.

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REFRIGERATION

A compressor or portion of a condensing unit supported from the ground shall rest on a concrete or other approved base extending not less than 3 inches (76 mm) above the adjoining ground level.

1105.3 Access. An unobstructed readily accessible opening and passageway not less than 36 inches (914 mm) in width and 80 inches (2032 mm) in height shall be provided and maintained to the compressor, valves required by this chapter, or other portions of the system requiring routine maintenance.

Exceptions:

(1) Refrigerant evaporators, suspended overhead, shall be permitted to use portable means of access.

(2) Air filters, brine control or stop valves, fan motors or drives, and remotely de-energized electrical connections shall be permitted to be provided access to an unobstructed space not less than 30 inches (762 mm) in depth, width, and height. Where an access opening is immediately adjacent to these items and the equipment is capable of being serviced, repaired, and replaced from this opening, the dimensions shall be permitted to be reduced to 22 inches (559 mm) by 30 inches (762 mm) provided the largest piece of equipment is removed through the opening.

(3) Cooling equipment, using Group A1 refrigerants or brine, located in an attic or furred space shall be permitted to be provided access by a minimum opening and passageway thereto of not less than 22 inches (559 mm) by 30 inches (762 mm).

(4) Cooling or refrigeration equipment, using Group A1 or B1 refrigerants or brine, located on a roof or on an exterior wall of a building, shall be permitted to be provided access as for furnaces in Section 304.3.

1105.4 Illumination and Service Receptacles. In addition to the requirements of Section 301.4, permanent luminaires shall be installed for equipment required by this code to be accessible or readily accessible. Such luminaires shall provide illumination to perform the required tasks for which access is provided. Control of the illumination source shall be provided at the access entrance.

Exceptions:

(1) Luminaires shall be permitted to be omitted where the fixed lighting of the building will provide the required illumination.

(2) Equipment located on the roof or on the exterior walls of a building.

1105.5 Ventilation of Rooms Containing Condensing Units. Where not in a refrigerant machinery room, rooms or spaces in which a refrigerant-containing portion of a condensing unit is installed shall be provided with ventilation in accordance with Section 1105.5.1 or Section 1105.5.2. Ventilation for machinery rooms shall comply with Section 1106.0.

1105.5.1 Permanent Gravity Ventilation Open- ings. Permanent gravity ventilation openings of not less

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(2) The resulting mixture does not change the refrigerant safety group. [ASHRAE 15:7.5.1.7]
CMC § 1503.9.5 Medium relevance — show source text
Valves for

nonpotable application . . . . . . . . . . . . . . . . . . .1503.9.5 Vent connectors, fuel gas . . . . . . . . . . . . . . . .509.10.11

Water meters and submeters . . . . . . . 601.2.1, 601.2.1.1,

601.2.1.2, L 407.4 Water pressure regulators and strainers . . . . . . . .608.2 ACCESSIBLE, DEFINITION . . . . . . . . . . . . . . . . . . . .203.0 ACCESSIBLE, READILY, DEFINITION . . . . . . . . . . . .203.0

ACCESSIBLE PLUMBING FACILITIES

For persons with disabilities . . . . . . . . . . . . . . . . .403.2 Protection against contact . . . . . . . . . . . . . . . . . . .403.3 Where required . . . . . . . . . . . . . . . . . . . . . . . . . . .403.1 ACCESSORY DWELLING UNIT, DEFINITION . . . . . . .203.0

ACRYLONITRILE-BUTADIENE-STYRENE

(ABS) PIPE . . . . . . . . . . . . . . . .203.0, Table 313.3, 701.2, Table 701.2, 705.1

705.9.4, 903.1, 1101.4,

1101.4.2.1, 1104.4.2.2

AIR GAPS

Backflow prevention . . . . . . 603.2, Table 603.2, 603.3.1, Table 603.3.1, 603.4.4

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.0

Discharge from drinking

water treatment units . . . . . . . . . . . . . . . . . . . . . 611.2

AIR TANK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .710.11

ALTERATIONS AND REPAIRS

Fuel gas piping . . . . . . . . . . . .1203.1, 1213.1.2, 1213.4.2

Health care facilities . . . . . . . . . . . . . . . . . . . . . . .1301.5

Plumbing systems . . . . . . . . . . . . . . . . . .102.4, 301.2.5 ALTERNATE MATERIALS, DESIGN,

AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . .301.3

ALTERNATE WATER SOURCE

Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .203.0
CMC § 211.0 Medium relevance — show source text
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amended (amended
sections listed below)
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that are listed below
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225.0||||X||||||||||||||X||||||| |Adopting Agency
Adopt Entire Chapter
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amended (amended
sections listed below)
Adopt only those sections
that are listed below
Chapter/Section
203.0
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This 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 1.11.0.

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CHAPTER 2

DEFINITIONS

201.0 General.

201.1 Applicability. For the purpose of this code, the following terms have the meanings indicated in this chapter.

No attempt is made to define ordinary words, which are used in accordance with their established dictionary meanings, except where a word has been used loosely, and it is necessary to define its meaning as used in this code to avoid misunderstanding.

202.0 Definition of Terms.

202.1 General. The definitions of terms are arranged alphabetically according to the first word of the term.

203.0 – A –

ABS. Acrylonitrile-butadiene-styrene. Accepted Engineering Practice. That which conforms to technical or scientific-based principles, tests, or standards that are accepted by the engineering profession. Accessible. Where applied to a fixture, connection, appliance, or equipment, “accessible” means having access thereto, but which first may require the removal of an access panel, door, or similar obstruction. **Accessible, Readily.
CMC § 2.1 Medium relevance — show source text
Meters and submeters . . . . . . . . . . . . . 601.2.1, 601.2.1.1,

601.2.1.2, L 407.4 Plumbing fixtures . . . . . . . . . . . . . . . . . . . . . . . . . .402.1 Pool heaters on/off switch . . . . . . . . . . . . . .L 503.3.6(1) Rainwater storage tanks . . . . . . .1603.4, 1603.5, 1603.6, K 105.0, K 105.3.1 Septic tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . .H 501.5 Shutoff valves . . . . . . . . . . . . . . . .606.3, 606.6, 1210.9,

1210.9.1, 1210.9.2,

1210.9.4, 1212.5.3,

1212.6, 1327.2,

E 403.9, E 403.13(2), E 403.13(6) Sumps . . . . . . . . . . . . . . . . . . . . . . . . . . . .710.10, 810.3

Toilet facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . .422.4

Trap seal primers . . . . . . . . . . . . . . . . . . . . . . . . .1007.1 Valve and Appurtenance Access Door Sign . .1505.9.2 Vacuum pumps . . . . . . . . . . . . . . . . . . . . . . . .C 501.2.1

Valves for

nonpotable application . . . . . . . . . . . . . . . . . . .1503.9.5 Vent connectors, fuel gas . . . . . . . . . . . . . . . .509.10.11

Water meters and submeters . . . . . . . 601.2.1, 601.2.1.1,

601.2.1.2, L 407.4 Water pressure regulators and strainers . . . . . . . .608.2 ACCESSIBLE, DEFINITION . . . . . . . . . . . . . . . . . . . .203.0 ACCESSIBLE, READILY, DEFINITION . . . . . . . . . . . .203.0

ACCESSIBLE PLUMBING FACILITIES

For persons with disabilities . . . . . . . . . . . . . . . . .403.2 Protection against contact . . . . . . . . . . . . . . . . . . .403.3 Where required . . . . . . . . . . . . . . . . . . . . . . . . . . .403.1 ACCESSORY DWELLING UNIT, DEFINITION . . . . . . .203.0

ACRYLONITRILE-BUTADIENE-STYRENE
CMC § 207.0 Medium relevance — show source text
Ductless Mini-Split System. A heating and cooling equipment that includes one or multiple indoor evaporator, air handler, or both units, an outdoor condensing unit that is connected by refrigerant piping, and electrical wiring. A ductless mini-split system is capable of cooling or heating one or more rooms without the use of traditional ductwork.

Dwelling. A building or portion thereof that contains not more than two dwelling units.

Dwelling Unit. A building or portion thereof that contains living facilities, including provisions for sleeping, eating, cooking, and sanitation, as required by this code, for not more than one family.

207.0 – E –

Easily Accessible. See Accessible, Readily . Effective Ground-Fault Current Path. An intentionally constructed, low impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors. [NFPA 54:3.3.33]

Electric Duct Heaters. A heater located in the airstream of a forced-air system where the air-moving unit is not provided as an integral part of the equipment.

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DEFINITIONS

Family. [HCD 1] “Family” is an individual or two or more persons who are related by blood or marriage, or otherwise, live together in a dwelling unit. Field-Applied Grease Duct Enclosures. A listed system evaluated for reduced clearances to combustibles and as an alternative to a duct with its fire-rated enclosure. [NFPA 96:3.3.22.2.2]

Fire Barrier. A fire-resistance-rated wall or assembly of materials designed to restrict the spread of fire in which continuity is maintained.

Fire Code. Whenever the term “Fire Code” is used in this code, it shall mean the California Fire Code, Title 24, Part 9.

Fire Partition. An interior wall or partition of a building that separates two areas and serves to restrict the spread of fire but does not qualify as a fire wall.

Fire Resistance Rating. The time, in minutes or hours, that materials or assemblies have withstood a fire exposure as established in accordance with ASTM E119 or UL 263.

[NFPA 96:3.3.25]

Fire-Resistive Construction. Construction in accordance with the requirements of the building code for the time period specified.

Fire Wall. A wall separating buildings or subdividing a building to prevent the spread of the fire and having a fire resistance rating and structural stability. [NFPA 96:3.3.26] Fireplace Stove. A chimney-connected, solid-fuel-burning stove (appliance) having part of its fire chamber open to the

room.

Flammable Vapor or Fumes. The concentration of flammable constituents in air that exceeds 25 percent of its Lower Flammability Limit (LFL).

Flood Hazard Area. The greater of the following two areas:

(1) The area within a floodplain subject to a 1 percent or greater chance of flooding in any given year.
CMC § 7.8.1.1 Medium relevance — show source text
** System shutoff valves shall be readily accessible for operation and installed so as to be protected from physical damage. System shutoff valves shall be marked with a metal tag or other permanent means attached by the installing agency so that the gas piping systems supplied through them can be readily identified. [NFPA 54:7.8.1.1, 7.8.1.2]

1310.11.1.1 Shutoff Valves for Multiple House Lines. In multiple-tenant buildings supplied through a master meter, through one service regulator where a meter is not provided, or where meters or service regulators are not readily accessible from the appliance or equipment location, an individual shutoff valve for each apartment or tenant line shall be provided at a convenient point of general accessibility. In a common system serving a number of individual buildings, shutoff valves shall be installed at each building. [NFPA 54:7.8.3.1] 1310.11.2 Emergency Shutoff Valves. An exterior shutoff valve to permit turning off the gas supply to each building in an emergency shall be provided. The emergency shutoff valves shall be plainly marked as such and their locations posted as required by the Authority Having Jurisdiction. [NFPA 54:7.8.3.2] 1310.11.3 Shutoff Valve for Laboratories. Each laboratory space containing two or more gas outlets installed on tables, benches, or in hoods in educational, research,

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FUEL GAS PIPING

commercial, and industrial occupancies shall have a single shutoff valve through which all such gas outlets are supplied. The shutoff valve shall be accessible, located within the laboratory or adjacent to the laboratory’s egress door, and identified. [NFPA 54:7.8.3.3] 1310.11.4 System Shutoff Valves. Where a system shutoff valve is installed, the valve shall comply with Section 1308.12. [NFPA 54:7.8.4]

1310.12 Prohibited Devices. Devices shall not be placed within the interior of gas piping or fittings where such devices reduce the cross-sectional area or otherwise obstruct the free flow of gas, except where allowance in the piping system design has been made for such devices. [NFPA 54:7.9] 1310.13 Systems Containing Gas-Air Mixtures Out- side the Flammable Range. Where gas-air mixing machines are employed to produce mixtures above or below the flammable range, they shall be provided with stops to prevent adjustment of the mixture to within or approaching the flammable range. [NFPA 54:7.10] 1310.14 Systems Containing Flammable Gas-Air Mixtures. Systems containing flammable gas-air mixtures shall be in accordance with Section 1310.14.1 through Section 1310.14.6.

1310.14.1 Required Components. A central premix system with a flammable mixture in the blower or compressor shall consist of the following components:

(1) Gas-mixing machine in the form of an automatic gas-air proportioning device combined with a downstream blower or compressor.

(2) Flammable mixture piping, minimum Schedule 40.

(3) Automatic firecheck(s).
California Mechanical Code Medium relevance — show source text

2
5
10
15|36
38
51
NA
NA|93
69
63
NA
NA|57
47
44
39
NA|56
57
75
95
NA|190
136
128
116
NA|111
93
86
79
72|80
80
102
128
158|325
225
216
201
186|186
149
140
131
124|116
115
144
182
220|499
337
326
308
290|283
224
217
203
192|153
148
182
228
272|713
473
459
438
418|388
314
298
284
269| |20|0
2
5
10
15
20|35
37
50
NA
NA
NA|96
74
68
NA
NA
NA|60
50
47
41
NA
NA|54
56
73
93
NA
NA|200
148
140
129
NA
NA|118
99
94
86
80
NA|78
78
100
125
155
186|346
248
239
223
208
192|201
165
158
146
136
126|114
113
141
177
216
254|537
375
363
344
325
306|306
248
239
224
210
196|149
144
178
222
264
309|772
528
514
491
469
448|428
344
334
316
301
285| |30|0
2
5
CMC § 5.08 Medium relevance — show source text
minute per square foot = 5.08 [(L/s)/m [2] ]

405.0 Ventilation for Residential Occupancies.

405.1 General. Rooms or occupied spaces within residential occupancies, where the occupants are nontransient, shall be designed to have mechanical ventilation and exhaust air in accordance with Section 405.2 through Section 405.5.

405.1.1 Natural Ventilation. Where approved by the Authority Having Jurisdiction, natural ventilation shall be permitted for Climate Zone 1, Climate Zone 2, or for thermally conditioned buildings for less than 876 hours

per year.

405.2 Ventilation Air Rate. The required mechanical ventilation outdoor air rate ( Qtot ) shall be as calculated in accordance with Equation 405.2.

Exception: For existing buildings and where permitted by the Authority Having Jurisdiction, the total mechanical ventilation ( Qtot ) is not required where Qtot is calculated to be less than 15 ft [3] /min (7.08 L/s).

Qtot = 0.03 Afloor + 7.5 ( Nbr + 1) (Equation 405.2)

Where:

Qtot = Total required ventilation outdoor air rate, CFM (L/s) Afloor = Floor area, ft [2] (m [2] ) Nbr = Number of bedrooms more than 1

For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s

405.2.1 Reduced Ventilation Air Rate. Where permitted by the Authority Having Jurisdiction, the mechanical ventilation air rate required in Section 405.2 shall be permitted to be reduced where an infiltration rate is determined in accordance with ASTM E779.

405.3 Bathroom Exhaust. A mechanical exhaust directly to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations. [HCD 1 & HCD 2] Each bathroom shall also be mechanically ventilated in accordance with Division 4.5 of the California Green Building Standards Code (CALGreen).

405.3.1 Exhaust Rate. The exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s) for intermittent operation and 25 ft [3] /min (11.8 L/s) for continuous operation. 405.4 Kitchen Exhaust. A mechanical exhaust system that discharges directly to the outdoors shall be provided in each kitchen. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations.

Exception: Recirculating systems installed in accordance with Section 516.0 and the manufacturer’s installation

instructions.
CMC § 510.9.2 Medium relevance — show source text
FIGURE 510.9.2

EXHAUST TERMINATION DISTANCE FROM FRESH AIR INTAKE (FAI) OR OPERABLE DOOR OR WINDOW

[NFPA 96: FIGURE 7.8.3]

511.0 Air Movement.

511.1 Exhaust Fans for Commercial Cooking Opera- tions. Exhaust fans shall be installed in accordance with Section 511.1.1 through Section 511.1.6. Exhaust fans shall comply with UL 705 and be installed in accordance with the manufacturer’s installation instructions.

511.1.1 Upblast Fans. Upblast fans with motors surrounded by the airstream shall be hinged and supplied with flexible weatherproof electrical cable, and service hold-open retainers. Installation shall conform to the requirements of Section 510.9. Upblast fans shall have a drain directed to a readily accessible and visible grease receptacle not to exceed 1 gallon (4 L). [NFPA 96:8.1.2.1 – 8.1.2.3]

511.1.2 In-Line Exhaust Fans. In-line fans shall be of the type with the motor located outside the airstream and with belts and pulleys protected from the airstream by a greasetight housing. In-line fans shall be connected

to the exhaust duct by flanges securely bolted as shown in Figure 511.1.2(1) through Figure 511.1.2(4), or by a system specifically listed for such use. Flexible connectors shall not be used. [NFPA 96:8.1.3.1 – 8.1.3.3]

511.1.2.1 Accessibility. If the design or positioning of the fan allows grease to be trapped, a drain directed to a readily accessible and visible grease receptacle not exceeding 1 gallon (4 L), shall be provided. In-line exhaust fans shall be located in easily accessible areas of adequate size to allow for service or removal. Where the duct system connected to the fan is in an enclosure, the space or room in which the exhaust fan is located shall have the same fire

resistance rating as the enclosure. [NFPA 96:8.1.3.4 – 8.1.3.6]

511.1.3 Utility Set Exhaust Fans. Utility set exhaust fans shall be installed in accordance with Section

511.1.3.1 through Section 511.1.3.3.

511.1.3.1 At the Rooftop. Fans installed at the rooftop termination point shall be in accordance with the following:

(1) Section 510.9.1 and Section 510.9.1.2.

(2) Vibration isolation connectors shall be permitted.

(3) A drain shall be directed to a readily accessible and visible grease receptacle not to exceed 1 gallon (4 L).

511.1.3.2 Within the Building. Fans installed within the building shall be in accordance with the following:

(1) Located in an accessible area of adequate size to allow for service or removal. [NFPA 96:8.1.4.2]

(2) Flexible connectors shall not be used. [NFPA 96:8.1.4.6]

(3) Exhaust fans shall have a drain directed to a readily accessible and visible grease receptacle not to exceed 1 gallon (4 L). [NFPA 96:8.1.4.7]

Frequently asked questions

What if a service panel can be removed from outside without tools — is that "readily accessible"?

No. The code definition distinguishes removal of any access panel, door, or similar obstruction. If reaching the device requires removing a panel (even if tool-less), it is Accessible, not Accessible, Readily (CMC § 203.0).

Does “accessible” mean I can leave the panel off permanently?

No. “Accessible” only describes the state of reachability; equipment locations and required protective enclosures are governed by other sections. Leaving a panel off may violate listing, enclosure, or safety requirements even if it improves access. Check the equipment-specific sections (e.g., § 1105.3) for mandated openings and protections.

Which code sections should I check when a plan reviewer requires “readily accessible” equipment?

Start with the equipment-specific access sections (example: § 1105.3 for compressors) and then review illumination and service requirements (§ 1105.4) plus any fuel-gas or ventilation provisions that reference accessibility.

If a shutoff valve is behind a door in a locked room, is it readily accessible?

If the door or any obstruction must be opened or removed to reach the valve, it is not “readily accessible.” Safety-related shutoffs are typically required to be reachable without such barriers — see fuel gas shutoff requirements in § 1310.11.

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Related in the CMC

How are 'Appliance' and 'Appliance, Vented' defined?

What do 'Approved', 'Listed' and 'Labeled' mean under the CMC?

Key 'A' definitions: Accessible, Approved, Appliance, Listed/Labeled

California Mechanical Code