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Glass Lightning Rod Insulators


Lightning rod insulators (abbreviated LRIs) actually predate communication insulators!  These insulators were used to insulate the rod itself from its mounting as well as the grounding cable that would carry the current to the ground down the side of the house or barn that these were normally used on.  There is currently no hobby numbering system for LRIs.  Although the bulk come in shades or aqua, there are also a great variety of styles and colors as shown below.  Thanks to Dwayne Anthony, Jim Colburn and Terry Drollinger for many of these great photographs!

The single groove and cross top styles use a metal mounting plate around the base to hold and the ground wire fits in the top slot and ties through the hole.  

Tab style

Dual tab style

cross top

Reyburn egg style

Enggren Patent

Enggren Patent

These less common tab styles have a tab with a screw guide to make them more secure. These styles mount at the base and have a hole to support a wire to tie the ground cable. They are designed to the Stebbins patent of June 25, 1867.
These are known as block styles which are mounted on the outside with the ground wire through the middle.
These are tab styles -- they would fit in a C shaped mount where the tab would prevent them from coming loose.  Thanks to Jim Colburn & Dwayne Anthony for these photos
These unusual styles are like small spools and can be found in a wide variety of colors.
Here are two examples made to a July 3, 1855 patent by Robert D. Dwyer or Richmond, VA.  The left one is marked SALAMANDER/PATENTED with the patent date on the other side.  These great photographs courtesy of Jim Colburn. Purple Cross-top Through hole style with original hardware
One of the earlier styles, the Otis insulator, nicknamed the wiggle top,  was patented August 26th, 1851 by George W. Otis of Lynn, MA.  It is believed that Sandwich glass made many of these.  Thanks again to Jim Colburn and Terry Drollinger for these pictures.


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