Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 164, § 81

Gas and electric companies or persons engaged in the manufacture and sale or distribution of gas or electricity shall keep their books and accounts in a form to be prescribed by the department, and the accounts shall be closed annually, so that a balance sheet can be taken therefrom. Manufacturing companies in which the manufacture of gas or electricity is a minor portion of their business shall be required to keep accounts of the expenses and income of their gas or electric business only.