(a) Except as otherwise provided in Subsection (b), if the local law of this state governs perfection of a security interest or agricultural lien, the office in which to file a financing statement to perfect the security interest or agricultural lien is:
(1) the office designated for the filing or recording of a record of a mortgage on the related real property, if:
(A) the collateral is as-extracted collateral or timber to be cut; or
(B) the financing statement is filed as a fixture filing and the collateral is goods that are or are to become fixtures; or
(2) the office of the Secretary of State, in all other cases, including a case in which the collateral is goods that are or are to become fixtures and the financing statement is not filed as a fixture filing.
(b) The office in which to file a financing statement to perfect a security interest in collateral, including fixtures, of a transmitting utility is the office of the Secretary of State. The financing statement also constitutes a fixture filing as to the collateral indicated in the financing statement that is or is to become fixtures.