Mass. Gen. Laws ch. 164 § 80
Gas and electric companies shall have an office in a town where their works are located and, unless otherwise authorized by the department, shall keep in said office all books and papers required by law to be kept within the commonwealth, and also such books as may be required to show their receipts, expenditures, indebtedness and financial condition; and shall at all times, upon application, submit their books to the inspection of the department and its duly authorized employees. The department may from time to time, by its members or its duly authorized employees, examine all books, records, contracts, documents, papers and memoranda of such corporations, and shall have free access thereto for such purpose at any and all reasonable times.
Mass. Gen. Laws ch. 164, § 80