Section 336.9-501 - FILING OFFICE(a)Filing offices. 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 central filing system operated by 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)Filing office for transmitting utilities. The office in which to file a financing statement to perfect a security interest in collateral, including fixtures, of a transmitting utility is the central filing system operated by the Office of the Secretary of State. The financing statement also constitutes a fixture filing as to the collateral indicated in the financing statement which is or is to become fixtures.