Oil Insulator Bird Feeder
Reprinted from "INSULATORS - Crown Jewels of the Wire", January 1974, page 20
RESEARCH DIVISION
Dear Dora:
Recently I purchased this insulator or whatever it be. The only number is
B-17307, found inside at top of the glass, where the pin should rest, no
threads, no wire groove. I would like to know if this insulator has shown up any
other place. I would appreciate hearing from anyone about it.
W. M. Bramlett
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Dear Mr. Bramlett,
In our first year of Crown Jewels (1969) this same question popped up several
times. In December 1969 issue Don Shinner sent in info. on this, and I believe
there are several varieties of this oil insulator, plus several sizes. We had
one large unembossed one and still have the mini embossed one. I've seen several
different ones at shows. Yours is a mini in size. Thanks for writing, and hope
the following info. copied from Mr. Shinner's letter in the December 1969 issue
will help you:
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"This is an oil insulator, manufactured by Electric Storage Battery Co.,
Rising Sun & Adams Ave., Philadelphia 20, Pa. This insulator has not been
manufactured since 1918 and I am not sure at what date they quit producing
these. A better means of production did away with these. These insulators were
used on storage batteries.
"We have a 'mini' insulator of this type. It is embossed "E.S.B.
Co./PHILA.PA." It is green in color and 2-1/8 inches diameter, inside hole
7/8 inch across, 3/4 inch deep, middle stem is 1-1/8 inch across, 5/8 inch long.
Overall bottom diameter is 2 inches.
"I have the following information on these insulators. 'Whenever a
number of open cells are in use, unless precautions be taken, electrical leakage
between the cells invariably occurs. This leakage is due chiefly to the
semi-conducting nature of the thin layer of moisture which frequently covers not
only the glass containing the cells, but the unimmersed parts of the elements,
and over the shelves on which the cells rest. To prevent this waste of energy,
the outside of the cells should occasionally be well cleaned and thoroughly
dried. Electrical leakage is greatly reduced if each cell be mounted on a glass
earthen-ware insulator, as shown in the illustration. The insulator here shown
is in two parts and of a mushroom shape. The lower cup contains a small quantity
of some non-evaporating oil, and as the conducted moisture cannot bridge across
this, a nearly perfect insulating medium is obtained. These insulators are made
in various sizes and may be obtained in earthen-ware or glass. Those made of
glass are found to give the best results."'
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