The term “public service company” when used in this chapter shall mean every person, firm, corporation or association, or their lessees, trustees or receivers, other than a municipal corporation, now or hereafter engaged in business in this Commonwealth as a public utility and subject to regulation as to rates and service by the State Corporation Commission under the provisions of Chapter 10 (§ 56-232 et seq.) of this title; however, the term shall not include and the provisions of this chapter shall not be deemed to refer to common carrier railroad companies, the issuance of the stocks and securities of which are under regulation by the Interstate Commerce Commission. The term “total capitalization” as used in § 56-65.1 shall mean total common stockholders’ equity (common stock, additional paid-in capital and retained earnings), preferred stock, and total debt (long- and short-term debt) as shown on the utility’s books. The terms “securities” and “loan” as used in §§ 56-68 and 56-75 shall include every obligation, written or otherwise, the issuance of, or entry into, which is required to be approved or validated by this chapter.