75.—Any local authority which is an authorised undertaker may (subject to the provisions of this Act which relate to expenditure incurred by an authorised undertaker in respect of the construction, reconstruction, extension, equipment, or re-equipment of any works used as part of or in connexion with his undertaking) contract with any person for the execution and maintenance of any works needed for the supply by such local authority of electricity in accordance with the order or special Act by which such supply is authorised.