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Collectibles--General (Modern)/Large glass insulators.


Glass insulator
Glass insulator  

I was wondering if you could give me information about an insulator that I picked up at a flea market for $3. It is quite large and I think resembles the capital dome. It is a blueish green color. I was hoping to find the manufacturer, cd number, and a possible price.

Thank you for any information you could provide,

ANSWER: Interesting -- can I get some more pictures of this item?  A picture of the bottom and the pin hole would be useful.  Also -- are there any markings at all on the item?  This is an interesting piece and I need more data to fully identify it.

         Thanks, --Bob

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Inside Insulator
Inside Insulator  

Thanks for the quick reply!

The very top of the inside has a set of threads with what appears to be Vaseline. Then it is stepped out with a larger set of threads. On the third stepped out section before the inside of the skirt are large vertical groves. Under the skirt there are four concentric grooves that run around the bottom of the skirt. All are different sizes.

On the very bottom lip underneath of the skirt is either a "6" or a "9" in sight relief depending on which way it is supposed to be read. Rotating the insulator upside down 180 degrees on the same lip has "187" in slight relief.

There also appears to be a seam that starts to the left of the 6 or 9 when the insulator is upside down. The seam runs up over the top of the insulator and continues to the bottom of the skirt on the other side. It passes to the left of 187. Not sure if this was pieced together by a machine or not.

Thank you again for your time,

ANSWER: Thanks for the additional pictures.  I must admit this item has me stumped -- I have never seen an insulator like this, but must admit there are some insulator-like qualities of the item.  I'm about 60% convinced this is not an insulator, but the base does have grooves like an insulator would.  The closest thing I have seen is a multi-part insulator where multiple shells are cemented together.  Thanks for sending the picture -- what is the diameter of the base?


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It's no problem sending pictures. If you need others I would be happy to send more. I understand what you mean about not seeing another one like it. I have not seen another one like it either. I have been researching the different types of insulators online. That is why I figured I'd ask the expert. (wink, wink.)

The height of the item is about 7 inches tall from the base to the flat top. The circumference of the base is about 32 inches. The diameter of the base is a little less than 10 and a quarter inches.


In general I do not believe this is an insulator, but I can't say for sure, and I do not know what purpose it would have.  The glass appears to be similar to some French made insulators.  There are no US glass insulator makers that I could attribute this to.  If it is an insulator it would probably be part of a "Multi-part" - here are some examples:

These are made by cementing together multiple glass or porcelain "shells" to increase the resistance.  Again -- I don't think your item is an insulator, but I also do not know what it could be so  . . . . .  

Sorry I could not be of more help -- here is a link to more foreign multiparts:

         Thanks, -Bob

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Bob Berry


Questions related to collecting Glass Insulators and porcelain insulators - I can provide historical information as well as current collector values. I am also interested in purchasing insulators I need for my collection.


I have collected since the early 1970's and have much historical information, as well as knowledge of current insulator values.

National Insulator Association (

BS & MS in Electrical Engineering

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