Publication: The Journal of Electricity, Power and Gas
San Francisco, CA, United States
AS TO INSULATOR PINS.
REFERRING to the subject of metal insulator pins, attention has been called to the fact that some of the electrical companies of this city have lately installed a large quantity of metal pins to replace the wooden ones which have been heretofore used.
In the early part of the present year the Bay Counties Power Company made some experiments on their line with metal pins, and the results were so satisfactory that they substituted over 25,000 metal pins for the old-style wooden ones. The Standard Electric Company has also installed a large quantity of metal pins, and their engineers are very enthusiastic over the good results obtained.
The pins used by the Bay Counties Power Company are similar to the pin marked No. 1 in the illustration. They are placed in the holes in the cross-arms, and are secured to a bolt which passes through a hole in the lower end of the pin.
The Standard Electric Company is using the pin shown in illustration No. 2, which is similar to No. 1, except in size, and in having the base swaged to a smaller diameter than the body of the pin. This permits of a shoulder which sets firmly upon the cross arm, and is considered a desirable feature by some engineers.
In securing the insulator to the pins, either lead or cement is used. In some cases the tops are put on by the construction crew while out on the line, and in other cases they are put on at the warehouse before they are shipped. It is almost superfluous to say that these pins are the strongest part of a pole line construction. They are not weakened or damaged by sudden jars, nor any strain which would have a serious effect on the cross-arms. While these pins have not been in use long enough to prove the assertion, there is no reason to believe that they may not last longer than the poles or cross-arms, and thus be used again on a new arm. While the first cost of this type is more than that of wooden ones, their durability and strength are such that they are really by far the cheaper of the two.
The Benicia Agricultural Works have made a specialty of this class of work, and can furnish pins as illustrated, either plain, dipped or galvanized, or will make to order any special construction which may be desired. They are not only doing a large business in pins, but are also making many accessories of electrical line work, such as pole steps, cross-arm braces, lag screws, anchor rods, machine and carriage bolts. Any specifications submitted for special forgings of pins, or their other lines, will receive prompt attention.