(a) Except as otherwise permitted or required by this article, all fuel gas equipment and installations for supplying fuel gas to units or accessory buildings or structures, and fuel gas piping systems outside of permanent buildings in parks, shall comply with the requirements found in the California Plumbing Code, Chapter 12.

(b) The requirements for fuel gas equipment and installations within permanent buildings in parks are located in the California Mechanical Code, and the California Plumbing Code unless provided otherwise in this chapter. However, in a city, county, or city and county, which has assumed responsibility for enforcement of the Mobilehome Parks Act and Special Occupancy Parks Act, pursuant to sections 18300 and 18865 of the Health and Safety Code, and has adopted and is enforcing a plumbing and mechanical code equal to or greater than the requirements of The California Plumbing Code and California Mechanical Code, may enforce its code as it pertains to permanent buildings.