- Item 74836 - Ball-strain insulator, ca. 1920
- Contributed by Maine Historical Society
- Item 74836
- 4200px x 3521px - 14.0"w x 11.7"h @ 300dpi | Need a larger size?
- *Credit line must read: Collections of Maine Historical Society
Nicknamed the "Johnny Ball," this insulator is made of a composite material containing asphalt, shellac and asbestos.Show Details
Strain insulators are used in the guy wires supporting utility poles or radio antennas to break the electrical path and prevent short circuits or grounding.