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CD 331 - Insulator of the Week on Fri, 26 Sep 2008


Model 701

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(Since some great discussion just occurred here on the Pyrex CD 331, let's add it to the following, making it the IOTW)

Embossing: Corning Pyrex TM Reg. U.S. Pat. Off. Made in U.S.A.

Colors: Listed in clear, green tint and yellow tint. Not sure if I've ever seen one that is perfectly clear -- maybe more accurately described as off-clear? The green tint examples usually contain a hint of straw. The yellow tint examples can vary slightly in tone and lean toward straw.


These brutes weigh in at a whopping 38 pounds! They are the largest known North American glass pintype insulator. Produced in 1930 by Corning Glass works, these massive one-piece insulators were rated at 70,000 volts.

These brief comments on the Insulator of the Week are not intended to be complete and are presented to stimulate and encourage discussion and additional information from ICON. Now it's your turn to share info and/or post a photo of your favorite CD 331's!




Jimmy Burns commented on Fri, 26 Sep 2008

There were a few 331s still in service in Northwest Georgia as of last June mixed with three piece porcelain multis.

Jack Comer commented on Sat, 27 Sep 2008

Below are links to a couple of pictures of some CD 331s I posted a few years ago:

I remember well the first time I saw these glass giants in service. It was June of 1977. I had just rolled into the town of Bisbee, Arizona from a 1200 mile road trip, not realizing that this place would come to be my home for years to come. I had all but abandoned insulator collecting some 5 years earlier, but my eyes were still drawn upward, ever vigilant for the wild insulator, and I spotted them the first moment I drove by them when I pulled into town. I have admired these for over 30 years, but only from a distance. I do not posess one, though I'd like to. Bisbee is an old mining town established in the late 1800s. Before elctrification the Copper Queen mine had its own power plant, but I don't believe the CD331s were part of that service. The 331s pictured here were put into service by Arizona Public Service right where they still stand today, probably around the late forties or early fifties. The word from the local utility is that this glass insulator is a true champion. They are very durable, and rarely has one sustained enough damage that required it be replaced, unless vandalized by a rifle. There is no immediate plan to replace this line that I know of, so if you get down this way you can still see the CD331 in service. That may change though, as everything does. The mine is planning to open back up full bore since the copper prices are so high.

Nathan Lamkey commented on Fri, 26 Sep 2008

There is one still in service along the Columbia Gorge on the Oregon side. I didn't have my camera with me or I would have taken a picture of it.

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