Ohio Electric Porcelain Co.
A 1910 report by the State Geologist of Tennessee indicated that the Ohio Electric Porcelain Co. of East Liverpool, Ohio donated insulators for the state geological exhibit at Nashville. Companies donated material that they made in their factories so it can be argued that the company made some kind of insulator.
The 1907 Who's Who in New York City and State lists Walter G. Clark as an officer of the company.
Leonard, John W. (1907). Who's Who in New York City and State Containing Authentic Biographies of New Yorkers who are leqaders and Representatives in Various Departments of Worthy Human Achievement Including Sketches of Every Army and navy Officer Born in or Appointed from New york and Now Serving, of all the Congressmen from the State, State Senators and Judges and Ambassadors, Ministers and Consuls Appointed from New York. Third edition. New York City: L.R. Hamersly & Company. From Google Books.
Tenessee Geological Society. (1911). Administrative Report for 1910. Bulletin 3. By George H. Ashley. Nashville: Foster and Parkes Company. From the Harvard University Library and Google Books.