1308.2 Interconnections Supplying Separate Users.

Where two or more meters, or two or more service regulators where meters are not provided, are located on the same premises and supply separate users, the gas piping systems shall not be interconnected on the outlet side of the meters or service regulators. [NFPA 54:5.2.1] 1308.2.1 Interconnections for Standby Fuels. Where a supplementary gas for standby use is connected downstream from a meter or a service regulator where a meter is not provided, equipment to prevent backflow shall be installed. A three-way valve installed to admit the standby supply and at the same time shut off the reg

276 2025 CALIFORNIA MECHANICAL CODE

FUEL GAS PIPING

APPLIANCE	INPUT (Btu/h approx.)
Space Heating Units Warm air furnace Single family Multifamily, per unit Hydronic boiler Single family Multifamily, per unit	100 000 60 000 100 000 60 000
Space and Water Heating Units Hydronic boiler Single family Multifamily, per unit	120 000 75 000
Water Heating Appliances Water heater, automatic storage 30 to 40 gallon tank Water heater, automatic storage 50 gallon tank Water heater, automatic instantaneous Capacity at 2 gallons per minute Capacity at 4 gallons per minute Capacity at 6 gallons per minute Water heater, domestic, circulating or side-arm	35 000 50 000 142 800 285 000 428 400 35 000
Cooking Appliances Range, freestanding, domestic Built-in oven or broiler unit, domestic Built-in top unit, domestic	65 000 25 000 40 000
Other Appliances Refrigerator Clothes dryer, Type 1 (domestic) Gas fireplace direct vent Gas log Barbecue Gaslight	3000 35 000 40 000 80 000 40 000 2500

For SI units: 1000 British thermal units per hour = 0.293 kW

1308.4.2.3 Copper and Copper Alloy Pipe. Copper and copper alloy pipe shall not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet (scf) of gas (0.7 mg/100 L). [NFPA 54:5.5.2.3]

Threaded copper, copper alloy, or aluminum alloy pipe shall not be used with gases corrosive to such material. [NFPA 54:5.5.2.4]

1308.4.2.4 Aluminum Alloy Pipe. Aluminum alloy pipe shall comply with ASTM B241 (except that the use of alloy 5456 is prohibited), and shall be marked at each end of each length indicating compliance. Aluminum alloy pipe shall be coated to protect against external corrosion where it is in contact with masonry, plaster, or insulation or is subject to repeated wettings by such liquids as water, detergents, or sewage. [NFPA 54:5.5.2.5]

Aluminum alloy pipe shall not be used in exterior locations or underground. [NFPA 54:5.5.2.6]

ular supply shall be permitted to be used for this purpose.

[NFPA 54:5.2.2.1 – 5.2.2.2]