There are presently three systems in use to assist in identifying and cataloging insulators.
They are:
CD numbers, U-numbers, and M-numbers.
These are not numbers given, or used by the manufacturers, but are numbers assigned by certain collectors at a later date. Below you will find a brief explanation of each system, along with a comment on each one from its originator. (Detailed explanations can be found in the publications listed for each system.)
M-# MULTI-PART NUMBER.
A system invented by Mr. Elton of Buna, Texas in 1988, for identifying porcelain multi-part insulators.
Use of the CD numbers was first initiated by someone other than me in November of 1965, when early collector Helmer Turner asked for and received a list of numbers for use in his personal collection. It was later through his efforts that the CD numbers began to come into general use. They first appeared in my publication (The Glass Insulator in America, 1967 Report.)@ (Mr. N. R. Woodward)
U-# UNIVERSAL STYLE CHART NUMBER.
A system invented by Mr. Jack H. Tod of Phoenix, Arizona, in 1971, for identifying porcelain uni-part pin type insulators.
All the known shapes of uni-part porcelain insulators are shown in a published AUniversal Style Chart,@ the name stemming from the facts that many of the styles were universally made by a number of manufacturers, and also because the definitive style reference numbers in the chart are universally used by all collectors ...(therefore,) any insulator is easily and completely described simply by listing its style number, such as U-16, its color, and any markings. (Mr. Jack H. Tod)
CD CONSOLIDATED DESIGN NUMBER.
A system invented by Mr. N. R. Woodward of Houston, Texas, in late 1952 or early 1953 Every different glass pin type insulator shape found has been assigned its own CD number by Mr. Woodward as a means of identification.
The reason for the CD numbers is the need for approximate identification of Insulator styles regardless of their markings. Although a majority of insulators carry a manufacturer’s style number, many do not, and therefore carry no key to their style. It is also true that the same style insulator
may have several different numbers, assigned by different manufacturers at different times. It is also true the one manufacturer sometimes uses the same style number for totally different insulator types at different times. For example, there are three distinct styles of Hemingway No. 14. (Thus) it is seen that there is a definite need for a consolidated numbering system for identification proposes.
The Universal Style Chart for U. S. uni-part porcelains is published in Porcelain Insulators Guide Book, by Jack H. Tod. The Universal Style Chart for foreign uni-part porcelains is published in World Wide Porcelain Insulators, by Marilyn Albers and Jack H. Tod
Scale drawings of the CD numbers are published in The Glass Insulator in America, 1988 Report, by N. R. Woodward. Scale drawings of CD numbers for foreign insulators are published in Glass Insulators from Outside North America, Second Revision, by Marilyn Albers and N. R. Woodward.
