CMC · California Mechanical Code
Installation, supports & sealing
This hub summarizes CMC requirements for installing and supporting mechanical systems and for sealing ducts, penetrations and piping to meet fire, energy, and serviceability standards.
Last reviewed: July 6, 2026
Overview
This area of the California Mechanical Code (CMC) covers how mechanical systems are installed and anchored and how assemblies are closed and sealed — including hangers and anchors for piping and equipment, duct and exhaust joint closure, penetration firestopping, and liquidtight joints where condensate is present. For example, general hanger/support rules appear at §313.1 and related tables for spacing; refrigeration piping support rules are in §1109.6; and fuel‑gas piping support and sealing requirements are in §1310.3.
Sealing and closure of duct systems — including listed closure systems (UL 181) and duct leakage-test requirements — are found in Chapter 6 (see §603.9.1 and §603.9.2). Exhaust ducts also include requirements for liquidtight joints when condensate is present and for sealing penetrations through fire barriers with listed fire‑stopping equal to the barrier rating (see §506.4 and §506.3.2), while duct supports and spacing are specifically addressed in the exhaust provisions (see §506.7).
Why this matters: correct supports prevent mechanical damage, undue stress and vibration; proper sealing preserves fire containment, indoor air quality and energy performance; and listed materials/closure systems plus required testing provide a verifiable, code‑compliant installation. See the cited sections for the primary regulatory text and referenced standards.
In this section
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 506.3.2 High relevance — show source text
106 2025 CALIFORNIA MECHANICAL CODE
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EXHAUST SYSTEMS
506.3.2 Protection. Exhaust ducts passing through fire barriers of any fire resistance rating shall be protected by sealing the space around the duct with listed or approved fire stopping having a fire resistance rating equal to the fire resistance rating of the fire barrier.
[NFPA 91:4.2.13]
506.4 Condensate. Joints in duct construction shall be liquidtight when the conveying system contains condensable vapors or liquids in suspension. [NFPA 91:4.3.6.1]
506.4.1 Drainage. Provisions shall be made for drainage of condensate at low points in the duct. [NFPA 91:4.3.6.2]
506.5 Fittings. Fittings in Class 2, 3, and 4 systems shall be not less than two gauges thicker than the thickness required for straight runs. Flexible metallic duct shall be permitted to be used for connecting ductwork to vibrating equipment. Duct systems subject to wide temperature fluctuations shall be provided with expansion joints.
Branches shall connect to main ducts at the large end of transitions at an angle not exceeding 45 degrees (0.79 rad).
Except for ducts used to convey noncorrosive vapors with no particulate, accessible cleanouts shall be provided at 10 foot (3048 mm) intervals and at changes in direction. Access openings shall also be provided for access to sprinklers and other equipment within the duct that require servicing.
506.6 Explosion Venting. Ducts conveying explosive dusts shall have explosion vents, openings protected by anti-flashback swing valves, or rupture diaphragms. Openings to relieve explosive forces shall be located outside the building. Where relief devices cannot provide sufficient pressure relief, ductwork shall be designed to withstand an internal pressure of not less than 100 pounds-force per square inch (psi) (689 kPa).
Where a room or building contains a dust explosion hazard that is external to protected equipment, as defined in NFPA 654, such areas shall be provided with deflagration venting to a safe outside location.
Systems exhausting explosive mixtures shall be protected by an approved explosion relief system in accordance with NFPA 69.
506.7 Supports. Supports shall be of noncombustible materials, and the spacing shall not exceed 12 feet (3658 mm) for 8 inch (203 mm) ducts and 20 feet (6096 mm) for larger ducts.
506.8 Fire Protection. Sprinklers or other fire-protection devices shall be installed within ducts having a cross-sectional dimension exceeding 10 inches (254 mm) where the duct conveys flammable vapors or fumes. Sprinklers shall be installed at 12 foot (3658 mm) intervals in horizontal ducts and at changes in direction. In vertical runs, sprinklers shall be installed at the top and at alternate floor levels.
CMC § 519.1 High relevance — show source text
519.1 Where Required. Type II hoods shall be installed above equipment and dishwashers that generate steam, heat, or products of combustion, and where grease or smoke is not present.
Exceptions:
(1) Dishwashing machines connected to a Type II duct system and exhausted directly to the outdoors.
(2) Dishwashing machines with a self-contained condensing system listed in accordance with UL 921 and installed in a space where the HVAC system has been engineered to accommodate the latent and sensible heat load emitted from such appliances as approved by the Authority Having Jurisdiction. Such equipment shall be provided with an interlocking device to prevent opening of the appliance prior to completion of its cycle. 519.2 Construction of Type II Hoods. Type II hoods constructed of steel shall be not less than 0.024 of an inch (0.61 mm) (No. 24 gauge). Hoods constructed of copper shall be of copper sheets weighing not less than 0.17 ounces per square inch (oz/in [2] ) (7.47 kg/m [2] ). Joints and seams shall be substantially tight. Solder shall not be used except for sealing a joint or seam. 519.3 Type II Hood Exhaust System Net Airflow. The net airflow for Type II hoods shall be in accordance with Section 508.5.1.5 for light-duty cooking appliances. The net airflow for Type II hoods serving dishwashing appliances shall comply with Section 519.3.1.
519.3.1 Dishwashing Appliances. The net airflow for Type II hoods used for dishwashing equipment shall be not less than 200 cubic feet per minute (0.094 m [3] /s) per linear foot (m) of hood length.
519.4 Type II Exhaust Duct Systems. Ducts and plenums serving Type II hoods shall be constructed of rigid metallic materials in accordance with Chapter 6. Duct bracing and supports shall comply with Chapter 6. Ducts subject to positive pressure shall be adequately sealed.
519.5 Termination of Type II Hood Exhaust System. The exhaust system shall terminate in accordance with Section 502.2.2. Rooftop terminations shall be directed away
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EXHAUST SYSTEMS
from roof surfaces within 40 inches (1016 mm). The discharge outlet of moisture conveying exhaust ducts, such as dishwasher exhaust ducts, shall not terminate over a public way or over an area where condensate or vapor could create a nuisance or hazard.
519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3.
519.7 Independent Exhaust Duct System. Single or combined Type II exhaust systems shall be independent of all other exhaust systems.
2025 CALIFORNIA MECHANICAL CODE 133
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CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE
CHAPTER 6 – DUCT SYSTEMS
CMC § 8.10.4 High relevance — show source text
[ASHRAE 15:8.10.4] 1109.6 Support. In addition to the requirements of Section 1105.2, piping and tubing shall be securely fastened to a permanent support within 6 feet (1829 mm) following the first bend in such tubing from the compressor and within 2 feet (610 mm) of each subsequent bend or angle. Piping and tubing shall be supported at points not more than 15 feet (4572 mm) apart. 1109.7 Pipe Enclosure. Refrigerant piping and tubing shall be installed so that it is not subject to damage from an external source. Soft annealed copper tubing shall not exceed 1 [3] ⁄ 8 inches (35 mm) nominal size. Mechanical joints, other than approved press-connect joints, shall not be made on tubing exceeding [3] ⁄ 4 of an inch (20 mm) nominal size. Soft annealed copper tubing conveying refrigerant shall be enclosed in iron or steel piping and fittings, or in conduit, molding, or raceway that will protect the tubing against mechanical injury from an exterior source.
2025 CALIFORNIA MECHANICAL CODE 239
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REFRIGERATION
Exceptions: (1) Tubing entirely within or tubing within 5 feet (1524 mm) of a refrigerant compressor where so located that it is not subject to external injury. (2) Copper tubing serving a dwelling unit, where such tubing contains Group A1 refrigerant and is placed in locations not subject to damage from an external source. 1109.8 Visual Inspection. Refrigerant piping and joints erected on the premises shall be exposed to view for visual inspection prior to being covered or enclosed. Exception: Copper tubing enclosed in iron or steel piping conduit, molding, or raceway, provided there are no fittings or joints concealed therein. 1109.9 Condensation. Piping and fittings that convey brine, refrigerant, or coolants that during normal operation are capable of reaching a surface temperature below the dew point of the surrounding air and that are located in spaces or areas where condensation will cause a hazard to the building occupants or damage to the structure, electrical or other equipment shall be protected to prevent such damage. 1109.10 Identification. Piping shall be in accordance with the reference standard for identification. The type of refrigerant, function and pressure shall be indicated.
1110.0 Valves.
1110.1 More than 6.6 Pounds of Refrigerant. Systems containing more than 6.6 pounds (2.99 kg) of refrigerant shall have stop valves installed at the following locations: (1) The suction inlet of each compressor, compressor unit, or condensing unit. (2) The discharge of each compressor, compressor unit, or condensing unit. (3) The outlet of each liquid receiver. Exceptions: (1) Systems that have a refrigerant pumpout function capable of storing the entire refrigerant charge. (2) Systems that are equipped with the provisions for pumpout of the refrigerant. (3) Self-contained systems. [ASHRAE 15:9.12.4] **1110.2 More than 110 Pounds of Refrigerant.
CMC § 10.1.2 High relevance — show source text
[NFPA 96:10.1.2] 513.2 Types of Equipment. Fire-extinguishing equipment shall include both automatic fire-extinguishing systems as primary protection and portable fire extinguishers as secondary backup. [NFPA 96:10.2.1] 513.2.1 Identification. A placard shall be conspicuously placed near each Class K extinguisher that states that the fire protection system shall be activated prior to using the fire extinguisher. [NFPA 96:10.2.2]
513.2.2 Standard. Commercial cooking equipment that produce grease laden vapors shall be provided with a Type I Hood, in accordance with this Code, and an auto- matic fire extinguishing system that is listed and labeled for its intended use as follows:
(1) Wet chemical extinguishing system (NFPA 17A, Stan- dard for Wet Chemical Extinguishing Systems), com- plying with UL 300, Fire Testing of Fire Extinguishing Systems for Protection of Restaurant Cooking Equip- ment. All existing dry chemical and wet chemical extinguishing systems shall comply with UL 300, Fire Testing of Fire Extinguishing Systems for Protection of Restaurant Cooking Equipment. (2) Carbon dioxide extinguishing systems (NFPA 12, Standard on Carbon Dioxide Extinguishing Sys- tems ) . (3) Automatic fire sprinkler systems (NFPA 13, Stan- dard for the Installation of Sprinkler Systems). All existing dry chemical and wet chemical extinguishing systems shall comply with UL 300, no later than the sec- ond required servicing of the system following the effec- tive date of this section. Exceptions:
(1) Automatic fire-extinguishing equipment provided as part of listed recirculating systems shall comply with UL 710B. [NFPA 96:10.2.5] (2) [DSA-SS & SFM] Public school kitchens, without deep-fat fryers, shall be upgraded to a UL 300, Fire Testing of Fire Extinguishing Systems for Protection
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EXHAUST SYSTEMS
of Restaurant Cooking Equipment, compliant system during state-funded modernization projects that are under the jurisdiction of the Division of the State Architect. 513.2.3 Installation. Automatic fire-extinguishing systems shall be installed in accordance with the terms of their listing, the manufacturer’s installation instructions, and the following standards where applicable:
(1) NFPA 12
(2) NFPA 13
(3) NFPA 17
(4) NFPA 17A
(5) NFPA 750 [NFPA 96:10.2.6] 513.2.4 Modification of Existing Hood Systems. Any abandoned pipe or conduit from a previous installation shall be removed from within the hood, plenum, and exhaust duct. [NFPA 96:10.2.7.1]
513.2.4.1 Sealing. Penetrations and holes resulting from the removal of conduit or piping shall be sealed with listed or equivalent liquid-tight sealing devices.
[NFPA 96:10.2.7.2]
**513.2.4.2 Obstructions.
CMC § 12-17 High relevance — show source text
A. Soil chloride testing must be performed under the supervision of a state licensed professional corrosion or geotechnical engineer.
B. Soil chloride tests shall be taken in the vicinity of the proposed subsurface transformer in a location chosen to be adequately representative of all soil strata that could impact the structure of the enclosure or the equipment
Rev. #07: 12-17-20 072149 Page 1 of 3
UG-1 General Greenbook Requirements for Allowing Installation of Subsurface Transformers
in the enclosure, as determined and stated on the report submitted by the state licensed professional engineer in responsible charge.
C. The soil must be tested for chloride by one of the following applicable standards:
Chloride content per ASTM D4327, ASTM D512, CTM 422, or AASHTO T−291
If Chloride content is greater than 5,000 parts per million (ppm), enclosure requires waterproofing.
Groundwater level determination shall be performed by a state licensed professional geotechnical engineer and shall be based on site−specific borings and other information as deemed suitable by the state licensed geotechnical engineer in responsible charge.
Enclosures in low design groundwater level areas and where chloride content is greater than 5,000 ppm require waterproofing. If chloride content is less than 5,000 ppm, install the enclosure per Document 062000.
Enclosures in high design groundwater level areas require waterproofing.
Waterproofing includes the following:
A. Sealing of all conduits (terminators) entering the enclosure.
B. Application of waterproofing membrane on all exterior surfaces including the bottom of the bottom slab. Waterproofing may be applied by the supplier or it may be applied in the field. Where extensions are added in the field, seal the joint with the required sealant prior to installation of the extension, then apply the waterproofing over the joint. Note: ground rods shall be installed before backfilling and while temporary control of groundwater is in place. Seal ground rod holes with wet-use epoxy.
C. Application of protection boards on all exterior surfaces including the bottom of the bottom slab to prevent membrane damage during backfill operations.
D. Sealing of joints between enclosure sections or extensions.
E. Sealing of ground rod holes.
F. Do no break out the four knockouts located on the bottom slab of the enclosure.
Materials used for Waterproofing the Enclodosure
Waterproofing Membrane: Tremco’s TREMproof 250 GC fluid applied elastomeric waterproofing Membrane, minimum 215 mils wet thickness; Carlisle’s CCW Miradri 860/861 self−adhering sheet membrane, with manufacturer’ recommended adhesive primer; or approved equal
Protection Board: Tremco’s HDPE−40 protection sheet: Carlisle’s CCW 200V Protection Fabric, or approved equal.
3. Rayflate Duct Sealing System (RDSS) conduit seal. Refer to Document 062288.
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References Location Document
CMC § 7.1.7.3 High relevance — show source text
(2) Insulated copper conductor not less than 14 AWG.
Where tracer wire is used, access shall be provided from aboveground or one end of the tracer wire or tape shall be brought aboveground at a building wall or riser. [NFPA 54:7.1.7.3 – 7.1.7.3.2]
1310.2 CSST Piping Systems. CSST piping systems shall be installed in accordance with this code and the manufac turer’s installation instructions. [NFPA 54:7.1.8]
1310.3 Installation of Aboveground Piping. Piping installed aboveground shall comply with all of the following:
(1) Piping shall be securely supported and located where it will be protected from physical damage.
(2) Where passing through an exterior wall, the piping shall also be protected from corrosion by coating or wrapping with an inert material approved for such applications.
(3) The piping shall be sealed around its circumference at the point of the exterior penetration to prevent the entry of water, insects, and rodents.
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FUEL GAS PIPING
(4) Where piping is encased in a protective pipe sleeve, the annular spaces between the gas piping and the sleeve and between the sleeve and the wall opening shall be sealed.
(5) Piping installed outdoors shall be elevated not less than 3½ inches (89 mm) above the ground.
(6) Sealing materials shall be compatible with the piping and sleeve. [NFPA 54:7.2.1]
1310.3.1 Protective Coating. Where piping is in contact with a material or an atmosphere corrosive to the piping system, the piping and fittings shall be coated with a corrosion-resistant material. Any such coating used on piping or components shall not be considered as adding strength to the system. [NFPA 54:7.2.2]
1310.3.2 Building Structure. The installation of gas piping shall not cause structural stresses within building components to exceed allowable design limits. Approval shall be obtained before any beams or joists are cut or notched. [NFPA 54:7.2.3.1 – 7.2.3.2]
1310.3.3 Gas Piping to be Sloped. Piping for other than dry gas conditions shall be sloped not less than [1] ⁄ 4 inch in 15 feet (1.4 mm/m) to prevent traps. [NFPA 54:7.2.4]
1310.3.3.1 Ceiling Locations. Gas piping shall be permitted to be installed in accessible spaces between a fixed ceiling and a dropped ceiling, whether or not such spaces are used as a plenum. Valves shall not be located in such spaces.
Exception: Appliance or equipment shutoff valves required by this code shall be permitted to be installed in accessible spaces containing vented appliances.
1310.3.4 Prohibited Locations. Gas piping inside any building shall not be installed in or through a clothes chute, chimney or gas vent, dumbwaiter, elevator shaft, or air duct, other than combustion air ducts. [NFPA 54:7.2.5]
CMC § 6622-4229 High relevance — show source text
1 Kits have a 12 month shelf-life.
062288 Page 18 of 20 Rev. #20: 03−25−22
UG-1: Conduits Greenbook Underground Conduits
Instructions for Sealing Conduit Using RDSS
Notes
Consult the manufacturer’s instructions included in each kit.
Installation tool IT-16 is needed to install RDSS. This tool uses CO 2 cartridges. Both of these materials need to be ordered separately. See Figure 44 on Page 20 .
Select the appropriate RDSS size per Table 28.
When sealing three or more cables, the RDSS sealing clip listed on Table 34 must be used with the DRSS duct deal. One clip seals up to four cables.
Order RDSS as indicated in Table 29 on Page 20.
For additional reference, the link below provides an installation video. This video was developed by the manufacturer and may not reflect the use of the company required PPE. When performing this work, please be sure to use the appropriate PPE (i.e. long sleeves, hard hat, etc.) as required by PG&E. The video titled “RDSS − Rayflate Duct Seal System Installation and Removal” is posted in Microsoft Stream. Access Microsoft Stream at https://web.microsoftstream.com/ from PG&E intranet.
Table 28 RDSS Size Selection
Normal Duct
(Conduit)
Size (Inches)RDSS-45
Cable/Cable
Bundle
Diameter
(Inches)RDSS-60
Cable/Cable
Bundle
Diameter
(Inches)RDSS-75
Cable/Cable
Bundle
Diameter
(Inches)RDSS-100
Cable/Cable
Bundle
Diameter
(Inches)RDSS-125
Cable/Cable
Bundle
Diameter
(Inches)RDSS-150
Cable/Cable
Bundle
Diameter
(Inches)1-1/2 0-1.25 2 0-1.50 0-1.00 3 0-2.00 4 0-3.25 0-2.75 5 2 0-2.75-4.5 2.50-4.24 6 2 2.50-5.50 RDSS Clip
SizeN/A 75 75 100 125 150 1 One RDSS clip per RDSS seal is included in the kit. 2 For 5” and 6” ducts with cable bundle diameters less than listed on this table or empty; an RDSS-AT/AP-150 device must be used along with RDSS. RDSS-AT/AP-150 must be ordered separately. See Figure 44 on Page 20.
Figure 42 RDSS Seal and Clip
Figure 43 AT/AP-150 Device
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UG-1: Conduits Greenbook Underground Conduits
CMC § 9.1.8.1 High relevance — show source text
** Appliances and equipment shall be furnished either with load-distributing bases or with a sufficient number of supports to prevent damage to either the building structure or the appliance and the equipment.
[NFPA 54:9.1.8.1] 902.8.1 Structural Capacity. At the locations selected for installation of appliances and equipment, the dynamic and static load-carrying capacities of the building structure shall be checked to determine whether they are adequate to carry the additional loads. The appliances and equipment shall be supported and shall be connected to the piping so as not to exert undue stress on the connections. [NFPA 54:9.1.8.2] 902.9 Flammable Vapors. Appliances shall not be installed in areas where the open use, handling, or dispensing of flammable liquids occurs, unless the design, operation, or installation reduces the potential of ignition of the flammable vapors. Appliances installed in compliance with Section 305.1 through Section 305.1.2, Section 303.11, or Section 303.12 shall be considered to comply with the intent of this provision. [NFPA 54:9.1.9] 902.10 Solid-Fuel-Burning Appliances. Unless otherwise specified, solid-fuel-burning appliances shall be installed in accordance with NFPA 211 and the manufacturer’s instal lation instructions.
902.11 Combination of Appliances and Equipment. Any combination of appliances, equipment, attachments, or devices used together in any manner shall comply with the standards that apply to the individual appliance and equipment. [NFPA 54:9.1.19] 902.12 Protection of Gas Appliances from Fumes or Gases Other than Products of Combustion. Nondirect-vent appliances installed in beauty shops, barber shops, or other facilities where chemicals that generate corrosive or flammable products such as aerosol sprays are routinely used shall be located in a mechanical room separate or partitioned off from other areas with provisions for combustion and dilution air from outdoors. Direct vent appliances in such facilities shall be in accordance with the appliance manufacturer’s installation instructions. [NFPA 54:9.1.6.2]
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INSTALLATION OF SPECIFIC APPLIANCES
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903.2.3 Connection of Gas Engine-Powered Air Conditioners. Gas engines shall not be rigidly connected to the gas supply piping. [NFPA 54:10.2.3]
903.2.4 Clearances for Indoor Installation. The installation of air-conditioning appliances shall comply with the following requirements:
(1) Air-conditioning appliances shall be installed with clearances in accordance with the terms of their listing and the manufacturer’s instructions. {NFPA 54:10.2.4(1)}
(2) Air-conditioning appliances shall be permitted to be installed with reduced clearances to combustible material, provided that the combustible material or appliance is protected as described in Table 303.10.1 and such reduction is allowed by the manufacturer’s installation instructions. [NFPA 54:10.2.4(2)]
(3) Where the furnace plenum is adjacent to plaster on metal lath or noncombustible material attached to
CMC § 31.6 High relevance — show source text
(2) Use approved secondary multi−ways tap slices for PG&E to join PG&E’s secondary cable to customer owned cable. See Document 036640 for ordering information.
B. The installation and maintenance of special fittings (explosion−proof) and sealing compounds at both ends.
C. The type of cable required from the meter termination point to the connection point with PG&E. This section of cable is customer owned, installed and maintained.
- Prior to cable installation, prove all conduits free and clear by means of a mandrel PG&E approved. A PG&E-approved polyester, flat pulling tape, white with sequential footage markings every foot, and 2,500-pound minimum tensile strength ( Code M560154 ), must be installed in all conduits and attached to an end cap.
- Install a splice box whenever cable pulling tensions are exceeded, or a change in cable or conduit size is required. The applicant must contact the local PG&E office to determine these requirements.
- Test bypass facilities are required for both single phase and three phase non-residential installations regardless of the panel ampacity.
PG&E Requirements
If PG&E service conductors are to be run in a multiple conduit system, all phases and the neutral must be installed in each conduit that is used.
PG&E will furnish and install the underground service conductors and make connections in the applicant’s service termination enclosure.
Potential water intrusion into service conduits and meter termination facilities
A. Water intrusion into service conduits and meter termination facilities may occur if the source side of the service facilities (e.g., secondary splice box) is at an elevation greater than the meter termination facilities.
B. CPUC General Order 128, Rule 31.6 requires “Lateral ducts for services to buildings, through which water may enter buildings, must be plugged or sealed.”
C. When the intrusion of water into the service and metering equipment can be reasonably expected through lateral ducts, the conduits must be sealed at both ends using one of the PG&E approved sealing method shown in Document 062288.
D. If the meter termination facilities are significantly lower than the source side facilities, use the Rayflate Duct Sealing System (RDSS) conduit sealing system listed in Document 062288 .
063928 Page 2 of 9 Rev. #26: 03−25−22
Methods and Requirements for Installing Non-Residential Underground Electric Services 0 − 600 Volts to Customer-Owned Facilities
UG-1: Services Greenbook EDM
E. The applicant is responsible for providing a means to prevent the accumulation of excess water pressure in the service conduit system. This is accomplished by the following methods:
(1) For wall−mounted service and metering equipment install an enclosure, outside, at the base of the riser to the meter panel, or at a maximum of 6 feet away from the meter panel along the service run.
CMC § 6622-4229 High relevance — show source text
1 Quantities may vary due to variations encountered in construction.
Rev. #20: 03−25−22 062288 Page 17 of 20
UG-1: Conduits Greenbook Underground Conduits
Instructions for Sealing Conduit Using Foam
Notes
Within minutes, polyurethane foam expands to form a water and gas barrier that can be easily removed in the future.
Consult the manufacturer’s instructions included in each kit.
Duct Terminator
Cables
Figure 39 Details of a Polyurethane Seal
Step 1 Wipe off loose dirt and grime from cables.
Step 2 Install front dam (packing). Wind a strip of packing around each cable. Push the dam approximately 6 inches to 8 inches into the conduit. Install the back dam in the same manner as the front dam, and push it into the conduit until the dam is flush with the duct terminator.
Back Dam Flush With Duct Terminator
Figure 40 Front Dam Installation
Step 3 Insert the nozzle into the chamber between the dams and inject polyurethane.
Polyurethane Sealant
Figure 41 Nozzle Application
Table 27 Material Codes for Polyurethane Conduit Seal Kits [1]
Conduit Size Material Code Manufacturer C atalog Number 2” Through 6” 019178
Dura-Line (Arnco)
Hydro SealS-60-C6P 2” Through 6” 490813 Polywater
FST-250KIT-PGE 1 Kits have a 12 month shelf-life.
062288 Page 18 of 20 Rev. #20: 03−25−22
UG-1: Conduits Greenbook Underground Conduits
Instructions for Sealing Conduit Using RDSS
Notes
Consult the manufacturer’s instructions included in each kit.
Installation tool IT-16 is needed to install RDSS. This tool uses CO 2 cartridges. Both of these materials need to be ordered separately. See Figure 44 on Page 20 .
Select the appropriate RDSS size per Table 28.
When sealing three or more cables, the RDSS sealing clip listed on Table 34 must be used with the DRSS duct deal. One clip seals up to four cables.
Order RDSS as indicated in Table 29 on Page 20.
For additional reference, the link below provides an installation video. This video was developed by the manufacturer and may not reflect the use of the company required PPE. When performing this work, please be sure to use the appropriate PPE (i.e. long sleeves, hard hat, etc.) as required by PG&E. The video titled “RDSS − Rayflate Duct Seal System Installation and Removal” is posted in Microsoft Stream. Access Microsoft Stream at https://web.microsoftstream.com/ from PG&E intranet.
Table 28 RDSS Size Selection
CMC § 603.9.1 High relevance — show source text
DUCT SYSTEMS
603.9.1 Closure Systems. Joints and seams and reinforcements for air ducts and plenums listed and labeled to UL 181, shall be in accordance with the manufacturer’s installation instructions. Closure systems for sealing air ducts and plenums shall be listed and labeled in accordance with UL 181A or UL 181B, and marked in accordance with Table 603.9.1.
TABLE 603.9.1
CLOSURE MARKINGS
TYPE OF DUCTWORK STANDARD TYPE OF CLO-
SURE SYSTEMMARKING
Rigid Metallic or
Rigid FiberglassUL 181A Pressure
Sensitive Tape181A-P
Rigid Metallic or
Rigid FiberglassUL 181A Mastic Tape 181A-M
Rigid Metallic or
Rigid FiberglassUL 181A Heat
Sensitive Tape181A–H
Flexible Air DuctsUL 181B Pressure
Sensitive Tape*181B-FX*
Flexible Air DuctsUL 181B Mastic* 181B-M* - Mechanical fasteners shall be used in conjunction with a listed pressure sensitive tape or mastic in accordance with UL 181. Nonmetallic mechanical fasteners shall be listed and labeled in accordance with UL 181B and
labeled “181B-C.”
603.9.2 Duct Leakage Tests. [Not adopted by HCD] Ductwork shall be leak-tested in accordance with the SMACNA HVAC Air Duct Leakage Test Manual. Duct leakage tests shall be performed by a technician certified by the Associated Air Balance Council (AABC), the National Environmental Balancing Bureau (NEBB), the Testing, Adjusting and Balancing Bureau (TABB), or other equivalent approved agencies. Representative sections totaling not less than 10 percent of the total installed duct area shall be tested. Where the tested 10 percent fail to comply with the requirements of this section, then 40 percent of the total installed duct area shall be tested. Where the tested 40 percent fail to comply with the requirements of this section, then 100 percent of the total installed duct area shall be tested. Sections shall be selected by the building owner or designated representative of the building owner. Positive pressure leakage testing shall be permitted for negative pressure ductwork. The permitted duct leakage shall be not more than the following:
Lmax = CLP [0.65 ] (Equation 603.9.2)
Where:
Lmax = maximum permitted leakage, (ft [3] /min)/100 square feet [0.0001 (m [3] /s)/m [2] ] duct surface
area.
CL = six, duct leakage class, (ft [3] /min)/100 square feet [0.0001 (m [3] /s)/m [2] ] duct surface area at 1 inch water column (0.2 kPa).
P = test pressure, which shall be equal to the design duct pressure class rating, inch water column (kPa).
Exception: Transfer air duct operating at less than 1 inch of water column (0.25 kPa).
CMC § 0.03 Medium relevance — show source text
(5) A closet, bathroom, toilet room, kitchen, garage, boiler room, furnace room, or unconditioned attic.
(6) Rooms or spaces containing a fuel-burning appliance therein. Where such room or space serves as source of return-air.
Exceptions:
(1) This shall not apply to fireplaces, fireplace appliances, residential cooking appliances, direct vent appliances, enclosed furnaces, and domestic-type clothes dryers installed within the room or space.
(2) This shall not apply to a gravity-type or listed vented wall heating or cooling air system.
(3) This shall not apply to a blower-type heating or cooling air system installed in accordance with the following requirements:
(a) Where the return air is taken from a room or space having a volume exceeding 1 cubic foot (0.03 m [3] ) for each 10 Btu/h (0.003 kW) fuel input rating of fuel-burning appliances therein.
(b) Not less than 75 percent of the supply air is discharged back into the same room or space.
(c) Return-air inlets shall not be located within 10 feet (3048 mm) from an appliance firebox or draft diverter in the same enclosed room or confined space.
311.4 Return-Air Limitations. Return air from one dwelling unit shall not discharge into another dwelling unit through the heating or cooling air system.
58 2025 CALIFORNIA MECHANICAL CODE
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GENERAL REGULATIONS
311.5 California Energy Code Requirements for Res- idential Air Filtration. In mechanically ventilated residen- tial buildings, air filters shall be provided to clean outdoor air and return air prior to its delivery to occupied spaces where specified in California Energy Code Sections 150.0(m)12 and 160.2(b). The air filters shall comply with California Energy Code requirements for labeling, ventilation system design and installation, air filter efficacy, and air filter pressure drop.
312.0 Plumbing Connections. 312.1 General. Water supply, sanitary drainage, and backflow protection shall be in accordance with the California Plumbing Code .
313.0 Hangers, Supports, and Anchors. 313.1 General. Piping, tubing, appliances, and appurtenances shall be supported in accordance with this code, the manufacturer’s installation instructions, and in accordance with the Authority Having Jurisdiction. Seismic restraints shall be in accordance with the building code. 313.2 Material. Hangers, supports, and anchors shall be of sufficient strength to support the weight of the pipe or tubing and its contents. Piping or tubing shall be isolated from incompatible materials.
313.3 Suspended Piping. Suspended piping or tubing shall be supported at intervals not to exceed those shown in Table 313.3.
313.4 Alignment. Piping or tubing shall be supported in such a manner as to maintain its alignment and prevent sagging.
313.5 Underground Installation. Piping or tubing in the ground shall be laid on a firm bed for its entire length; where other support is otherwise provided, it shall be approved in accordance with Section 302.0.
313.6 Hanger Rod Sizes. Hanger rod sizes shall be not smaller than those shown in Table 313.6.
Frequently asked questions
Which CMC sections set hangers, supports and anchor rules?
Piping, tubing, appliances and appurtenances are required to be supported per §313.1 and its tables; refrigeration piping has additional fastening and spacing rules at §1109.6; and fuel‑gas piping support/spacing is in §1310.3.
How must ducts and plenums be sealed and tested?
Closure systems must be listed and labeled (UL 181) and used per §603.9.1. The CMC includes duct leakage test language at §603.9.2, though that testing provision carries adoption qualifications in some jurisdictions; liquidtight joints are required where condensate is present (§506.4).
What about penetrations through fire barriers?
Exhaust and other ducts that penetrate fire barriers must be protected by sealing the around‑duct annulus with listed fire‑stopping having a fire‑resistance rating equal to the barrier, per §506.3.2.
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