THEY COME IN DIFFERENT
According to WEBSTER'S DICTIONARY . . .
a Strain is a nonconducting substance or body, as
porcelain or glass, used in insulating wires, etc.
Cf. (compare) Conductor, nonconductor.
Radio Antenna and Electrical ... STRAINS
STRAIN INSULATORS were first used in tele-
graph sys tems to isolate the signal wire from the
ground while still supporting the radio antennas.
A "typical" strain insulator is a piece of glass
or porcelain that is shaped to accommodate two
cables. The shape of the insulator maximizes the
distance between the cables while also maximiz-
ing the loading transfer capacity of the insula-
tors. The total measurement of the ribs and the
space between the ribs determines the electrical
length of the insulator from eye to eye. A short,
compact in sulator with more ribs and deeper val-
leys has more electrical length than a longer one
with less or no ribs. Some strains are smooth
some have ribs.
They were used to break the electrical path in
any wire link, such as in guy wires used to sup-
port utility poles, dead-ending the ends of elec-
trical power lines, and overhead power lines.
Note that the interlocking connection wires on all
strain insulators (except radio an tenna strains)
prevent the wire from falling should the insulator
become broken. Several older styles of high volt-
age strain insulators intended to dead-end feed-
er wires were mounted vertically between two
cross-arms by means of a wooden or
metal rod or pipe. The large styles were
composed of a smaller porcelain part
cemented inside the larger diameter por -
Radio antenna strains were used in
homes, on military antennas, aircrafts,
commercial re peaters, TV and Radio
Broad cast antennas, and boats. Electrical
strains were used on power lines.
They were made by various glass, bot-
tle, and insulator manufacturers; porcelain man-
ufacturers; and marble manufacturing compa-
nies.There are hundreds of different names of
strains from various places. A few names are
Pyrex (NY), Fleron (NJ), Brilliant (OH), Sensory
(PA), A.G.K. (NY), Locke (MD), Ohio Brass (OH),
Knox (TN), Zicme (Columbia), L.S. Brach (NJ),
Birnbach (NY), and Lapp (NY).
Strains were made of porcelain, glass,
Steatite, plastic, metal, resin, fiberglass, com -
posite, wood, etc.
Where can you find old strains today? . . . You
can find them on/in barns, houses, old poles,
sales, flea markets, antique shops, and on the
Anatomy of a Strain
drawing from A Collectors Guide for Radio Antenna Insulators (CD)
Glass Radio Antenna Strains in Various Colors ...
Sharp Ribs - and - Round Ribs
This strain is
and was made by Star.
The color Nu-Blac
is a trademark dark
Radio Antenna and Electrical ... STRAINS
Artwork Courtesy of Old Familiar Strains. . . A great publication devoted to research on strains.
Example of how a radio antenna strain worked
PORCELAIN NAIL KNOB
Notice the different shapes and number of ribs and
no ribs of these strains
Egggg aanndd JJoohhnnnnyy BBaallll SSttrraaiinnss
Probably made by
Wooooddeenn aanndd GGllaassss SSttrraaiinnss
marked with backward
(Guy Wire Strains)
äxÇ áàÜt|Çá zÉà ytÇvç4
This jeweled-looking strain
was made by
D.C. Jenkins Glass Co.
L. S. BRACH
(Newark, New Jersey)
2'' 1½'' 1¾'' 2¼'' 2'' 2'' 2¼'' 1½''
Duquesne Light Co. / Embossed: D L Co
Poonnttiill GGllaassss aanndd EErrrroorrss
A Collectors Guide for Radio Antenna Insulators (CD) Bob Alexander and Jim Dombrowski
Old Familiar Strains Dan Howard and Keith Roloson
National Insulator Assoc. (NIA) ·
Lois and Steve Blair · Elton Gish · Caleb Thimell · Rick Soller
David Sztramski · Bernie Warren
"THANK YOU TO ALL"
... and a Special Thank You to Jim Dombrowski for his support and inspiration
overpour in eye
Notice at the ends where the strain was CUTfrom the pontil ... most are ground off at the ends
AWNING RINGS ...
They were NOTdesigned to be an insulator ...
BUTwere sometimes used as radio strains
What are they?
We sincerely hope that those of you who have ever said "WHAT IS A STRAIN?" or
"WHAT DOES A STRAIN DO?" ... will be able to answer that question now and be able to recognize
a strain the next time you see one.
Charles and Sandi Irons
Notice a piece
of the eye of
a strain still
when it was