The supply of gas and the pipeline capacity to transport this supply must be sufficient to meet all normal peak day demands for service and provide a reasonable reserve for emergencies. This subsection is not applicable to curtailable or interruptible gas service contracts, to less than full requirements gas supply and/or transmission service contracts, whether firm or interruptible, to stand-by gas supply and/or transmission service contracts, whether firm or interruptible, to service under interruptible tariffs or to where gas supply is obtained from or furnished by a third-party supplier.
Okla. Admin. Code § 165:45-3-7