(a) A person is not required to be licensed under this chapter to perform:
(1) plumbing incidental to and in connection with the business in which the person is employed or engaged if the person:
(A) is regularly employed as or acting as a maintenance person or maintenance engineer; and
(B) does not engage in plumbing for the public;
(2) construction, installation, or maintenance on the premises or equipment of a railroad if the person is an employee of the railroad who does not engage in plumbing for the public;
(3) plumbing if the person is engaged by a public service company to:
(A) lay, maintain, or operate its service mains or lines to the point of measurement; and
(B) install, change, adjust, repair, remove, or renovate appurtenances, equipment, or appliances;
(4) appliance installation and service work, other than installation and service work on water heaters, that involves connecting appliances to existing openings with a code-approved appliance connector if the person performs the work as an appliance dealer or an employee of an appliance dealer; or
(5) water treatment installations, exchanges, services, or repairs, other than the treatment of rainwater to supply a plumbing fixture or appliance.
(b) Work described by this section is subject to inspection and approval as provided by applicable state law or municipal ordinance.