Glass Pin Insulator- Owasha, Canada

Institution: Oshawa Museum

Province: Ontario Archaeology

Object: Insulators

Era: 19th Century

Glass insulators are remnants of mid 19th century electric transmission systems in U.S. and Canada. Pintypes, such as the one above, were grooved at the base to support wire conductors and threadless (underneath). This design offered little to no support from keeping them in place on utility poles. By the late 19th century, threadless insulators had been replaced with threaded glass and porcelain models, which were cheaper and required less resetting. .

The mark “Canadian Pacific RY CO” (Canadian Pacific Railway Company) built their railways beginning in 1880s, approximately 10-15 years after threadless insulators were phased out. Therefore, the company may have installed power lines well before the railways were actually completed.


  • Myers, Adrian T. “Telling Time for the Electrified: An Introduction to Porcelain Insulators and the Electrification of the American Home.” Technical Briefs in Historical Archaeology 5 (2010): 31-42.
  • McDougald , J. & C.  McDougald. “Insulators: a history and guide to north american glass pin type insulators” Online, 1990.