Section 7K. Whenever land or an easement therein is taken by the department by eminent domain for the purpose of relocating certain facilities of a public utility company, as authorized by section seven G, the said public utility company, its authorized agents or employees, after due notice by registered mail to the persons in possession of land so taken, may enter upon any such lands, waters and premises, not including buildings, as said company may deem necessary or convenient for the purpose of relocating its facilities, and such entry shall not be deemed a trespass, nor an entry under any condemnation proceedings which may then be pending.