(a) A gas utility that provides gas to a customer does not have an obligation to serve the customer or to maintain the gas supply or physical capacity to serve the customer if the customer:
(1) is a transportation, industrial, commercial, or other similar large-volume contract customer;
(2) is an end-use customer of the gas utility;
(3) reduces or ceases the purchase of natural gas or natural gas service from the gas utility; and
(4) purchases natural gas or natural gas service from another supplier or purchases an alternate form of energy.
(b) Subsection (a) does not apply to the extent that:
(1) the customer continues to purchase natural gas or natural gas service of any class from the gas utility; or
(2) the gas utility has a written contract to provide natural gas or natural gas service of any class to the customer.
(c) This section does not prevent the railroad commission from requiring a gas utility to comply with an order of the railroad commission in apportioning gas under a curtailment plan and order.
(d) Notwithstanding Subsection (a), a gas utility that has provided gas to a commercial customer is obligated to serve that customer if the gas utility has a sufficient gas supply and physical capacity to do so without reducing service to its other customers.