Granite insulator made from Maine granite
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[Newspaper] Publication: The Lima News Lima, OH, United States |
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ELECTRICAL NOTES · · Granite is not usually considered to be an insulator, but one of the electrical journals reports that insulators are made as follows: Maine granite is crushed and molded into form and molded at 3,000 degrees Fahrenheit. It resists all but hydrofluoric acid, and dots not crush at a lower pressure than 14,500 pounds per square inch, and gives a tensile strength of 480 pounds per square inch; 56,600 volts were required to pierce one-quarter of an inch of this material in the shape of cup insulators.
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