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Glass Strain Insulators

Although all relatively uncommon, there are a variety of glass strain insulators available.  These were typically used to insulate a telephone or power pole guy wire from ground.  This was done to protect from inductance causing a charge on the wire as well as to prevent galvanic affects from corroding the guy wires and anchor.  The North American versions of these have been assigned CD numbers in the 1130 to 1149 range.  

Here is a  CD strain known as a "johnny ball" due to its shape.  Both Hemingray and Brookfield were known to have made these styles, but none are marked.

End view of the CD 1138 glass johnny ball style strain.  These are by far the most common style of glass strains.  The CD 1138 is very similar but smaller in diameter.

Here is a CD 1130 egg style strain made by the California Glass Insulator Co.

End view of CD 1130 egg insulator.

This CD 1129 rare strain was made to insulate hanging street lights and was patented on November 8, 1887 by  Francis H. Soden and Henry Goehst.  Thanks to Brian Reicker for this picture.






This unusual CD 1149 strain is a crude, possibly home made, version with wires embedded into a glass sphere. Thanks to Brian Reicker for this picture.



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