325.0 Alternate Source of Power for Safe Tempera-tures

tures. [OSHPD 2] Mechanical equipment required to main- tain a safe temperature for residents shall be powered by an alternate source of power per California Electrical Code Sec- tion 517.1. The safe temperature shall be between 71°F to 81°F (21.6°C to 27.2°C).

62 2025 CALIFORNIA MECHANICAL CODE

GENERAL REGULATIONS

TABLE 303.10.1 REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTION [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]

	[NFPA 54: TABLE 10.2.4]
TYPE OF PROTECTION APPLIED TO AND COVERING ALL SURFACES OF COM- BUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:	WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:
TYPE OF PROTECTION APPLIED TO AND COVERING ALL SURFACES OF COM- BUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION	36 (INCHES)	36 (INCHES)	18 (INCHES)	18 (INCHES)	12 (INCHES)	12 (INCHES)	9 (INCHES)	9 (INCHES)	6 (INCHES)	6 (INCHES)
TYPE OF PROTECTION APPLIED TO AND COVERING ALL SURFACES OF COM- BUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)	ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (INCHES)
TYPE OF PROTECTION APPLIED TO AND COVERING ALL SURFACES OF COM- BUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.	USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.
TYPE OF PROTECTION APPLIED TO AND COVERING ALL SURFACES OF COM- BUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION	ABOVE (COLUMN 1)	SIDES AND REAR (COLUMN 2)	ABOVE (COLUMN 1)	SIDES AND REAR (COLUMN 2)	ABOVE (COLUMN 1)	SIDES AND REAR (COLUMN 2)	ABOVE (COLUMN 1)	SIDES AND REAR (COLUMN 2)	ABOVE (COLUMN 1)	SIDES AND REAR (COLUMN 2)
(1) 31⁄2 inch thick masonry wall without ventilated air space	––	24	––	12	––	9	––	6	––	5
(2) 1⁄2 of an inch insulation board over 1 inch glass fiber or mineral wool batts	24	18	12	9	9	6	6	5	4	3
(3) 0.024 inch (nominal 24 gauge) sheet metal over 1 inch glass fiber or min- eral wool batts reinforced with wire on rear face with ventilated air space	18	12	9	6	6	4	5	3	3	3
(4) 31⁄2 inch thick masonry wall with ventilated air space	––	12	––	6	––	6	––	6	––	6
(5) 0.024 inch (nominal 24 gauge) sheet metal with ventilated air space	18	12	9	6	6	4	5	3	3	2
(6) 1⁄2 of an inch thick insula- tion board with ventilated air space	18	12	9	6	6	4	5	3	3	3

	[NFPA 54: TABLE 10.2.4]
(7) 0.024 inch (nominal 24 gauge) sheet metal with ventilated air space over 0.024 inch (nominal 24 gauge) sheet metal with ventilated air space	18	12	9	6	6	4	5	3	3	3
(8) 1 inch glass fiber or mineral wool batts sand- wiched between two sheets 0.024 inch (nom- inal 24 gauge) sheet metal with ventilated air space	18	12	9	6	6	4	5	3	3	3

For SI units: 1 inch = 25.4 mm

Notes:

1 Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing. 2 All clearances shall be measured from the outer surface of the combustible material to the nearest point on the surface of the appliance, disregarding any intervening protection applied to the combustible material. 3 Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite the appliance or connector. 4 Where all clearance reduction systems use a ventilated air space, adequate provision for air circulation shall be provided as described. [See Figure 303.10.1(2) and Figure 303.10.1(3)] 5 At least 1 inch (25.4 mm) shall be between clearance reduction systems and combustible walls and ceilings for reduction systems using a ventilated air space. 6 Where a wall protector is installed on a single flat wall away from corners, it shall have a minimum 1 inch (25.4 mm) air gap. To provide adequate air circulation, the bottom and top edges, or only the side and top edges, or all edges shall be left open. 7 Mineral wool batts (blanket or board) shall have a minimum density of 8 pounds per cubic foot (lb/ft 3 ) (128 kg/m 3 ) and a minimum melting point of 1500°F (816°C). 8 Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1.0 British thermal unit inch per hour square foot degree Fahrenheit [Btu•in/(h•ft [2] - °F)] [0.1W/(m•K)] or less. 9 At least 1 inch (25.4 mm) shall be between the appliance and the protector. The clearance between the appliance and the combustible surface shall not be reduced below that allowed in Table 303.10.1. 10 All clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable. 11 Listed single-wall connectors shall be installed in accordance with the manufacturer’s installation instructions.

GENERAL REGULATIONS

Notes: 1 A – Equals the clearance with no protection specified in Table 802.7.3.3 and Table 904.3.2 and in the sections applying to various types of equipment. 2 B – Equals the reduced clearance permitted in accordance with Table 303.10.1. 3 The protection applied to the construction using combustible material shall extend far enough in each direction to make C equal to A.

FIGURE 303.10.1(1) 1, 2, 3 EXTENT OF PROTECTION NECESSARY TO REDUCE

CLEARANCES FROM GAS APPLIANCE OR VENT CONNECTORS

[NFPA 54: FIGURE 10.3.3.3(a)]

For SI units: 1 inch = 25.4 mm

FIGURE 303.10.1(3) MASONRY CLEARANCE REDUCTION SYSTEM

[NFPA 54: FIGURE 10.3.3.3(c)]

For SI units: 1 inch = 25.4 mm

Notes:

1 Masonry walls can be attached to combustible walls using wall ties.

2 Spacers shall not be used directly behind appliance or connector. FIGURE 303.10.1(2) WALL PROTECTOR CLEARANCE REDUCTION SYSTEM

[NFPA 54: FIGURE 10.3.3.3(b)]

64 2025 CALIFORNIA MECHANICAL CODE

GENERAL REGULATIONS

TABLE 313.3

HANGERS AND SUPPORTS

MATERIALS	TYPES OF JOINTS	HORIZONTAL			VERTICAL
Cast	Lead and Oakum	5 feet, except 10 feet where 10 foot lengths are installed1, 2, 3	5 feet, except 10 feet where 10 foot lengths are installed1, 2, 3	5 feet, except 10 feet where 10 foot lengths are installed1, 2, 3	Base and each floor, not to exceed 15 feet
Cast	Compression Gasket	Every other joint, unless over 4 feet then support each joint1, 2, 3	Every other joint, unless over 4 feet then support each joint1, 2, 3	Every other joint, unless over 4 feet then support each joint1, 2, 3	Base and each floor, not to exceed 15 feet
Cast-Iron Hubless	Shielded Coupling	Every other joint, unless over 4 feet then support each joint1, 2, 3, 4	Every other joint, unless over 4 feet then support each joint1, 2, 3, 4	Every other joint, unless over 4 feet then support each joint1, 2, 3, 4	Base and each floor, not to exceed 15 feet
Copper & Copper Alloys	Soldered, Brazed, Threaded, or Mechanical	11⁄2 inches and smaller, 6 feet; 2 inches and larger, 10 feet	11⁄2 inches and smaller, 6 feet; 2 inches and larger, 10 feet	11⁄2 inches and smaller, 6 feet; 2 inches and larger, 10 feet	Each floor, not to exceed 10 feet5
Steel Pipe for Water DWV	Threaded or Welded	3⁄4 inch and smaller, 10 feet; 1 inch and larger, 12 feet	3⁄4 inch and smaller, 10 feet; 1 inch and larger, 12 feet	3⁄4 inch and smaller, 10 feet; 1 inch and larger, 12 feet	Every other floor, not to exceed 25 feet5
Steel Pipe for Gas	Threaded or Welded	1⁄2 inch, 6 feet;3⁄4 inch and 1 inch, 8 feet; 11⁄4 inches and larger, 10 feet	1⁄2 inch, 6 feet;3⁄4 inch and 1 inch, 8 feet; 11⁄4 inches and larger, 10 feet	1⁄2 inch, 6 feet;3⁄4 inch and 1 inch, 8 feet; 11⁄4 inches and larger, 10 feet	1⁄2 inch, 6 feet;3⁄4 inch and 1 inch, 8 feet; 11⁄4 inches every floor level
Schedule 40 PVC and ABS	Solvent Cemented	All sizes, 4 feet; allow for expansion every 30 feet3	All sizes, 4 feet; allow for expansion every 30 feet3	All sizes, 4 feet; allow for expansion every 30 feet3	Base and each floor; provide mid-story guides; provide for expansion every 30 feet
CPVC	Solvent Cemented	1 inch and smaller, 3 feet; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 3 feet; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 3 feet; 11⁄4 inches and larger, 4 feet	Base and each floor; provide mid-story guides
CPVC-AL-CPVC	Solvent Cemented	1⁄2 inch, 5 feet; ¾ inch, 65 inches; 1 inch, 6 feet	1⁄2 inch, 5 feet; ¾ inch, 65 inches; 1 inch, 6 feet	1⁄2 inch, 5 feet; ¾ inch, 65 inches; 1 inch, 6 feet	Base and each floor; provide mid-story guides
Lead	Wiped or Burned	Continuous Support	Continuous Support	Continuous Support	Not to exceed 4 feet
Steel	Mechanical	In accordance with standards acceptable to the Authority Having Jurisdiction	In accordance with standards acceptable to the Authority Having Jurisdiction	In accordance with standards acceptable to the Authority Having Jurisdiction	In accordance with standards acceptable to the Authority Having Jurisdiction
PEX	Cold Expansion, Insert and Compression	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	Base and each floor; provide mid-story guides
PEX-AL-PEX	Metal insert and metal compression	1⁄2 inch 3⁄4 inch 1 inch	}	All sizes 98 inches	Base and each floor; provide mid-story guides
PE-AL-PE	Metal insert and metal compression	1⁄2 inch 3⁄4 inch 1 inch	}	All sizes 98 inches	Base and each floor; provide mid-story guides
PE-RT	Insert and Compression	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	Base and each floor; provide mid-story guides
Polypropylene (PP)	Fusion weld (socket, butt, saddle, electrofusion), threaded (metal threads only), or mechanical	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	1 inch and smaller, 32 inches; 11⁄4 inches and larger, 4 feet	Base and each floor; provide mid-story guides

For SI unit: 1 inch = 25.4 mm, 1 foot = 304.8 mm

Notes: 1 Support adjacent to joint, not to exceed 18 inches (457 mm). 2 Brace not to exceed 40 feet (12 192 mm) intervals to prevent horizontal movement. 3 Support at each horizontal branch connection. 4 Hangers shall not be placed on the coupling. 5 Vertical water lines shall be permitted to be supported in accordance with recognized engineering principles with regard to expansion and contraction, where first approved by the Authority Having Jurisdiction.

66 2025 CALIFORNIA MECHANICAL CODE

CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE