1974 >> August >> Porcelain Insulator News  

Porcelain Insulator News
by Jack H. Tod

Reprinted from "INSULATORS - Crown Jewels of the Wire", August 1974, page 10

Preferably direct porcelain news item and questions directly to Jack H. Tod, 3427 N. 47th Place, Phoenix, Ariz. 85018. All mail will be answered if reply stamp is enclosed, and the most newsworthy items and questions of general interest will be published as space permits.

HOW MUCH DO YOU REALLY KNOW ABOUT PORCELAIN INSULATORS?

As a little diversion for the dog days, we've prepared the following quiz for you. Really test yourself and try to answer all the questions before consulting the answers following the quiz. If you get 20 of the 50 questions right, we know you're a porcelain collector. Thirty right means you're a very studious porcelain buff, and it you score 40 or more correct, maybe you should fill in as editor of this column while I take a vacation.

PORCELAIN INSULATOR QUIZ

  1. Rank the following companies first to last by when they started making porcelain pin types: 
    __ Victor Insulators, Inc. 
    __ Hartford Faience Co. 
    __ Ohio Brass Co. 
    __ Gladding Corp. 
    __ Pinco 
    __ Lapp

  2. Ohio Brass Company's insulator plant is at Mansfield, Ohio.
    __ True __ False

  3. Guy strain insulators are designed for interlocking wire loops because porcelain is approximately 16 times stronger in compression than it is in tension. 
    __ True __ False

  4. Which of the following companies still make pin types? 
    __ General Electric Co. (Locke) 
    __ Lapp 
    __ Westinghouse 
    __ Thomas 
    __ Jerrery-Dewitt 
    __ Finlay

  5. Line Post insulators are individually tested in each quadrant direction at only 50% of the mechanical load rating. 
    __ True __ False

  6. The industry standard for acceptance of any given production lot of pin types is that 12-1/2% of the lot selected at random must all pass electrical puncture test without exception. 
    __ True __ False

  7. The only reason why one surface of the insulator is left unglazed is to afford a firing surface which won't weld itself to the resting surface in the kiln. 
    __ True __ False

  8. Dry process pin types were popularly used in low voltage applications because they were considerably cheaper to make than wet process insulators. 
    __ True __ False

  9. Forestry insulators are usually made as split knobs because it is cheaper to make them that way, and the crack between halves does no harm on phone lines. 
    __ True __ False

  10. One reason why thru-hole "Mine Type" insulators were used in mines on vertical pins was to allow moisture from above to run down through the pin hole instead of onto the outer surface where it would short the wire. 
    __ True __ False

  11. All porcelain pin types meant for use in power applications have a conductor groove in the crown top. 
    __ True __ False

  12. The firing temperature of electrical porcelain is: 
    __900 degrees F 
    __1480 degrees F 
    __1850 degrees F 
    __2200 degrees F

  13. A well made glass insulator has approximately the same dielectric strength as a well made porcelain. 
    __ True __ False

  14. The tooling used to make porcelain insulators must allow for a firing shrink of approximately 12%.
     __ True __ False

  15. Porcelain insulators are glazed to prevent the absorption of moisture by the body of the insulator.
     __ True __ False

  16. Do porcelain pin types ever have drip points? 
    __ Yes __ No

  17. Conventional suspension insulator disks with the cap cemented on top and the pin cemented into the bottom place the porcelain in tension. 
    __ True __ False

  18. Which of the following companies rarely marked their unipart pin type insulators? 
    __ Pittsburg High Voltage 
    __ Hartford Faience Co. 
    __ General Porcelain Co. 
    __ New Lexington High Voltage Porcelain Co.

  19. Which of the following companies marked essentially every pin type they made? 
    __ Locke 
    __ Thomas 
    __ Ohio Brass

  20. Various porcelain insulator companies have collectively made less than 12,000 different types of insulators over the years. 
    __ True __ False

  21. All porcelain pin types with two side grooves and without a top groove are transposition insulators. 
    __ True __ False

  22. Most current pin type power insulators are basically little different from designs created over 50 years ago and indicate it's hard to improve on a sound original design. 
    __ True __ False

  23. Fogbowl and Fog Type insulators are used in areas of contamination even though fog is never present there.
    __ True __ False

  24. Embossed (raised letters) markings are found on dry process porcelains where the dies can be punched with the marking as with dies for making glass insulators. There is one example of a true embossed marking on wet process pin types. What marking in this? 
    ____________________

  25. Match up each of the following marking methods with the stage of manufacturing process where the marking is applied to the insulator.
    __ Embossed      (a) just before glazing dried insulator 
    __ Incuse        (b) marking incorporated in forming die 
    __ Underglaze    (c) immediately after green trimming 
    __ Overglaze     (d) after kiln firing & electrical test 
    __ Sandblast     (e) last step before kiln firing

  26. Nail knobs and small solid knobs are occasionally found with black, brown or blue glazes, and these were used to code special switching circuits. 
    __ True __ False

  27. The standard glaze during the early years of porcelain manufacture was white; the Imperial and early Thomas insulator styles are rare to unknown in brown. 
    __ True __ False

  28. A closed-end guy strain insulator is one with a wire hole through each of its ends. 
    __ True __ False

  29. A "reversible" cleat or split knob is one where both the mating halves are identical with each other. 
    __ True __ False

  30. The term "ceramic" is an incorrect one for modern pin type porcelain insulators. 
    __ True __ False

  31. Fred Locke was the first one to make high-voltage porcelain insulators. 
    __ True __ False

  32. Prior to the development of electrical porcelain wiring insulators in the early 1890's, wooden insulators were used for surface wiring and led to many fires. 
    __ True __ False

  33. Several insulator manufactories burned to the ground, but which of the following had the distinction of having burned to the ground twice? 
    __ Jeffery-Devitt, Kenova, W. Va. 
    __ Lima Insulator Co., Lima, N.Y. 
    __ New Haven Porcelain Co., New Haven, W. Va. 
    __ Imperial Porcelain Works, Trenton, N.J.

  34. It is a slow and expensive process to make insulators by casting liquid clay slip, and no company has ever based its main production on this method. 
    __ True __ False

  35. Paraffin-resist methods of affording an unglazed firing surface are relatively modern, and any insulator with a firing surface made by carving, sanding or fettling off the unwanted glaze can be assumed to have been made before about the time of the first World War. 
    __ True __ False

  36. Which of the following glaze colors is extremely hard to make on porcelain and has never been used in any regular production of porcelain insulators?
    __ Blue 
    __ Green 
    __ Red 
    __ Yellow

  37. White insulators are always much scarcer than brown ones and are therefore worth more in all cases. 
    __ True __ False

  38. There are many varieties of blue porcelain pin types, but all of these have been made by only 3 companies. 
    __ True __ False

  39. The modern "sky" glaze porcelains are made to a given specification of the National Electrical Manufacturer's Assn. and are relatively identical for each company. 
    __ True __ False

  40. A number of porcelain insulator styles have been made to copy the various amber glass insulator styles. 
    __ True __ False

  41. Collectors do not want multi art pin types (two or more parts cemented together), and they have little or no collector value. 
    __ True __ False

  42. Low-voltage secondary distribution pin types are generally not manufactured with "radio treated" tops because radio interference problems usually don't occur on lines operating under about 6600 volts. 
    __ True __ False

  43. Collector value of porcelain pin types is determined mainly by the insulator style (shape). 
    __ True __ False

  44. Hewlett-type strain and suspension insulators lost their popularity because they were less reliable than the modern styles of suspension insulators. 
    __ True __ False

  45. Suspension insulators used in horizontal strings (the deadend position) must be rated for higher voltage because the underside in completely wetted by rain. 
    __ True __ False

  46. Illinois Electric Porcelain sold insulators under "The Macomb Line" throughout its life, and the M in the Triangle-M Illinois marking stands for "Macomb". 
    __ True __ False

  47. One U.S. pin type manufacturer was known for making many insulators to customer specifications and sold a sizeable amount of its production to Canadian companies and to various foreign countries. What manufacturer was this? 
    ______________________

  48. Johns-Manville made a number of different porcelain insulator styles, some being marked "JOHNS-MANVILLE"
    __ True __ False

  49. Large insulators with flat metal base plates and top caps are used for and referred to as "Switch & Bus" insulators. 
    __ True __ False

  50. As compared with glass insulators, marking errors on porcelain pin types are relatively few in number. 
    __ True __ False

PORCELAIN QUIZ ANSWERS

  1. Ohio Brass (1907), Lapp (1916), Pinco (1920), Hartford (1925), Victor Insulators Inc. (1935), Gladding (1963) 

  2. False, That's where the main company is, but the insulator plant is at Barberton, a suburb of Akron, Ohio. 

  3. True.

  4. None of them. The only companies still at it are I-T-E, Pinco, Chance, McGraw-Edison, O-B and Gladding.

  5. True, the theory being that any firing flaw which would break at full load will break at 50% (so help me Hannah!). 

  6. False. Every single insulator is 100% electrically tested and is rejected if it does not pass.

  7. True. 

  8. True.

  9. False. They are made that way so they can be installed on Lines already strung, as in replacing broken insulators, and also so that new lines need not be threaded through all insulators before tensioning.

  10. True. Mine insulator pins were made fluted or in split form to assist in the passage of water. Also when used an duplex insulators upside down under crossarms. , they will not trap water which would freeze and break the insulator. 

  11. False. Side-tie styles are commonly used for secondary distribution circuits. 

  12. 2200 degrees F. 

  13. True; the disadvantage of glass insulators for many power applications is their relatively inferior mechanical strength.

  14. True. 

  15. False. Electrical porcelain is completely nonporous. The reason for the glaze is to furnish a surface which is more readily cleaned by rainwater, and also to provide a less objectionable color than the white body. 

  16. Yes, they all do. In porcelain nomenclature, any exposed edge or rim from which water drips to a lover level is termed a drip point.

  17. False. As shown in this sketch, proper design of the cap and pin pressure surfaces places the porcelain in compression as it should be. 

  18. Pittsburg and New Lexington. 

  19. Ohio Brass Co. 

  20. False. The number would exceed a million different kinds. Just one company alone (Lapp) has issued over 300,000 drawings for various porcelain insulator designs they have made to date.

  21. False. Many power insulators have one or more grooves cut under the tie-wire groove solely to create a longer electrical leakage path from tie wire to pin. 

  22. True. 

  23. True. The name stemmed from the fact that flashovers on contaminated insulators tended to be triggered when the fog rolled in, but contamination is still a problem in areas which don't even have fog. 

  24. The Ohio Dream Co. marking used up until 1940. Thereafter the marking is a pseudo embossed marking made with a stamp after trimming, and this we term "recess-embossed".

  25. Embossed - b; Incuse - c; Underglaze - a; overglaze - e; Sandblast - d. 

  26. False. These were included in outdoor radio antenna kits sold by various radio companies and mailorder houses, and which included a roll of antenna wire, a couple of radio strain insulators, a lightning arrestor, etc. The dark glaze colors made these items less conspicuous on the house. 

  27. True. On the other hand, Fred Locke started out with a light brown glaze in 1898 and didn't develop a white glaze until 1901. Most items with "Fred Locke" markings are much scarcer in white than they are in brown.

  28. True. 

  29. True. 

  30. False. It is technically correct, but the more definitive term "porcelain" is used to differentiate from other insulators made of steatite, alumina, etc. 

  31. False. He was preceded by General Electric (Schenectady), Peru Elec. Mfg. Co., Imperial Porcelain Works and Thomas. After only jobbing glass insulators for many years and porcelain insulators for about three years, he built his own porcelain insulator plant in 1898. He was considered the father of the industry because his plant was built exclusively for the manufacture of wet process high-voltage insulators.

  32. True. 

  33. Lima Insulator Co. In 1908, rebuilt and bought out by Locke Insulator Mfg. Co. in 1910, only to burn down again in 1919 (subsequently rebuilt and owned by Pinco). The other plants listed only burned to the ground one time each. The Kenova plant was never rebuilt. 

  34. False. Jeffery-Dewitt built its plant for the production of suspension insulators by casting and made nearly all its insulator types by casting, and this competitive disadvantage was a factor in the company's demise in the 1930's. 

  35. True.

  36. Red, which fires to black at normal firing temperature. Ohio Brass made a small lot with "great difficulty" for a fire alarm company. They ended up firing them in the lab kiln and said, "never, never, never again." 

  37. False. This is true for most relatively modern items, but many early items were normally made in white, and brown ones of these are rare and desirably varieties. 

  38. False. All companies since the early 1900's have made blue ones at one time or another either as stock items or on special order.

  39. True. The polar coordinates on the Munsell "gray" color chart are specified for hue and intensity, and it is up to each manufacture to brew his own glaze slip to match this color specification within a given tolerance.

  40. False. It's the other way around. 

  41. False. The modern, large multiparts have little collector appeal, but older and more unusual styles and colors are desirable collector items, especially the smaller varieties. 

  42. True 

  43. False. Value is based on a combination of insulator style, color and rarity of marking. Each factor in itself can make an otherwise worthless item a good item, just as is with glass insulators. The object is to find an unusual style in a good color and with a rare marking, and then you have a "super goody".

  44. False. They were possibly even more reliable, but, their complicated assembly hardware did not lead itself to easy replacement of faulty units in strings on activated transmission lines.

  45. False. In fact, on some lines the ones in the vertical strings can fail first due to underside contamination deposits not being washed away by rainwater.

  46. True. 

  47. Pittsburg High Voltage Insulator Co. 

  48. False. J-M never had a porcelain plant. They cataloged and sold a very large line of porcelains, most of which were Thomas insulators, but never made then. Pittsburg, New Lexington and possible others made insulators for J-M and marked many of these with the J-M name for the customer. 

  49. True. 

  50. True.



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