New Stress Figures for Poles

Washington, D. C., Dec. 22.-Another, and a most important step forward in standardization practice, has been taken, according to announcement by the American Standards Association, of New York City. It concerns the ultimate fiber stresses for poles, of which the public utilities companies of the United States require annually approximately four millions for use by telegraph, telephone, railways, and electric light companies.

To visualize the importance of this pole industry and how important it is to know as nearly as possible the burden which the poles can bear when laden with wires and subject to pressure by wind, snow, sleet, one may imagine all these poles placed end to end; and he would find that the total length would circumscribe the earth at the equator and there would be sufficient poles remaining to pierce the earth from pole to pole.

The new American Standard values for the strength of wood in the form of poles are as follows: Creosoted southern pine, 740O pounds; chestnut, 6000 pounds; western red cedal, 5600 pounds, and northern white cedar, 3600 pounds per square inch. As the greatest stress upon the pole ociurs immediately above the line where it enters the ground it is at this point the figures most critically apply.

Under the provisions of the National Electrical Safety Code the new values automatically replace the old figures of 6500 pounds for dense yellow pine, and 5000 pounds for other yellow pine, chestnut and western red cedar, whi,ch have been in general use by pole line engineers. Northern white cedar remains unchanged.

The new standards are the result of an extensive study conducted by the American Standards Association's Sectional Committee on Wood Poles. This committee was organized in 1924, under the sponsorship of the telephone group, embracing the Bell system and the United States Independent Telephone Association. The Chairman of the Committee is Dr. R. L. Jones, Director of Apparatus Developrhent in Bell Telephone laboratories.

A partial list of the membership of the committee includes representatives of the American Telephone and Telegraph Company, the United States Independent Telephone Association, the Western lJnion Telegraph Company, the Postal Telegraph-Cable Company, the National Electric Light Association, the American Institute of Electrical Engineers, the Ameri,can Railway Association, the American Electric Railway Association, the American Society for Testing Materials, the U. S. Bureau of Standards, the U. S. Forest Products Laboratorv. the American WoodPreservers' Association, the Westein Red Cedar Association, the Northern White Cedar Association, and other pole producers.