(a) A public utility may not directly or indirectly provide service to the public under a franchise or permit unless the utility first obtains from the commission a certificate that states that the public convenience and necessity requires or will require the installation, operation, or extension of the service.
(b) Except as otherwise provided by this chapter, a public utility may not furnish or make available retail public utility service to an area in which retail utility service is being lawfully furnished by another public utility unless the utility first obtains a certificate that includes the area in which the consuming facility is located.