No public service company shall henceforth make, extend or renew any loan of money to any affiliated interest or assume, extend or renew any obligation or liability whatsoever of any affiliated interest, whether as guarantor, endorser, surety or otherwise, unless the Commission shall first have approved such loan or assumption, or the extension or renewal of such loan, obligation, or liability, as being not inconsistent with the public interest, and then only upon such terms and conditions as may be set forth in the order of the Commission approving such transaction. The Commission shall, after the filing of such a loan, obligation, or liability, approve or disapprove the loan, obligation, or liability within sixty days. The sixty-day period may be extended by Commission order for an additional period not to exceed thirty days. The loan, obligation, or liability shall be deemed approved if the Commission fails to act within sixty days or any extended period ordered by the Commission. This section shall not be construed so as to invalidate or impair any such loan, obligation, or liability lawfully made, extended or renewed, or assumed, extended or renewed, and entered into prior to March 29, 1934.