Classification Systems in the Hobby

The Classification Systems

Glass - N.R. "Woody" Woodward developed a Consolidated Design (CD) system in the 1960s that is used for both North American pintype glass insulators and foreign pintype glass insulators. The system has been expanded to include battery rests, glass spools, nail knobs, guy wire strains, and other miscellaneous glass. For foreign glass insulators, Marilyn Albers has worked with Woody to produce the reference on the subject. For North American glass, Woody published and updated his CD system for many years but now the updates only show up in the price guide published by John and Carol McDougald.

Porcelain - Jack Tod published and updated a guide to porcelain insulators with his Universal numbering (U-number) system. Elton Gish is currently doing this work.

Multipart Insulators - Elton Gish developed a system for identifying multipart insulators (M-numbers) in 1988. The first number of any M-number indicates the number of pieces comprising the insulator (e.g., an M-4380 has four pieces cemented together). Within each grouping, insulators are generally ordered by size (e.g., the M-4380 is larger than the M-4360).

New Discoveries

One of the delights of collecting is finding an insulator that has not been previously reported. Certain discoveries are better than others because of how unexpected they are. Fitting the new discovery into the currently existing body of knowledge can sometimes be tricky and involves copyright issues. In any case, it is important to document your discovery and publicize it to the hobby as many collectors have taken pride in doing.

What is the best discovery? These can range from major new designs to trivial differences between insulators. Listed below are what I consider to be the ranking by importance of different discoveries.

  1. A new design. Finding an insulator in a shape that has not been reported before is generally a top discovery. Many collectors specialize in getting one of each CD or U number so finding a new design adds another piece for them to find. Insulators for which only a few examples are known to exist can command tens of thousands of dollars for this reason.
  2. A new marking. The marking must be substantially different to be considered second on this list. Minor punctuation variations, for example, would not count. However, finding a previously known style but with an previously unreported company's name on the insulator is very exciting. The marking confirms the company made or had made for them the insulator. Such was the case with a CD 263 glass insulator embossed General Electric which sold for much more than a typical CD 263.
  3. A new feature. New features are almost as good as a new design. Examples of new features are radio treatments, larger or smaller pinholes, metric pinholes, transition embossings, or size variations.
  4. A new color. In glass, there are numerous possible shades so the significance of a new color depends on how different it is from other known colors and what the color actually is. For example, if aqua and green shades of an insulator are known, the discovery of a green-aqua shade would not be surprising. On the other hand, if only clear and aqua shades of an insulator are known and a cobalt blue shade is discovered, that would be be a major discovery. Some such discoveries, in fact, have turned out to be fakes.
  5. A new oddity. Since billions of insulators were manufactured, it is likely that all kinds of oddities exist in insulators. These include underpours, overpours, bubbles, out-of-round shapes, ghost embossings, double strikes, upside down strikes in porcelain, thumbprints in porcelain glazes, off-centered parts of the insulator (e.g., the dome of a glass insulator is shifted off the mold line), flashovers, rocks, and nails. In insulators manufactured in the early years, these were more common. More modern insulators had higher quality control and are much less likely to have these.
  6. Minor variations. These include punctuation variations, insulators that are much heavier or lighter than usual, variations in the number of drip points, mold reworks, variations in the size of the embossing, a date code from the end of production, and mold codes (e.g., Pyrex CD 128s have over a hundred mold code letters).

Where do new designs fit? Generally it will be up to the copyright holder to decide where additions go. For North American glass insulators, N.R. "Woody" Woodward makes that determination. For certain parts of his Consolidated Design (CD) system, other people make the assignments. Ray Klingensmith assigns CD numbers for threadless insulators. Kevin Lawless developed CD numbers for battery rests and Charlie Irons took over this task when Kevin died. For North American porcelain insulators, Jack Tod developed a Universal (U) numbering system to identify them. Elton Gish currently assigns these numbers since Jack died many years ago. Elton also assigns numbers to multipart insulators (M-numbers). For foreign glass insulators, Marilyn Albers and N.R. Woodward are in charge of this. For foreign porcelain insulators, Marilyn Albers and Jack Tod made the assignments.

There is an organizing system to each of the different classification methods.