Minerallac impregnated insulator (Unity)

[Trade Journal]

Publication: Telephony

Chicago, IL, United States
vol. 62, no. 5, p. 156-157, col. 1-2,1

Minerallac Impregnated Insulator and Pin.

A combined insulator and pin, of one piece of wood, impregnated with a compound which gives it the highest insulating qualities, is expected to become exceedingly popular in the telephone field during the coming year. It represents a good deal more than the wiping out of the cost of carrying insulators around separate from the pins, carrying them up the pole separate, and screwing them on to the pins by hand with expensive linemen's labor. There is economy after the material is in place. It represents a saving at the start, and a continued saving every year it stands in use.

This combined insulator and pin is turned out of a solid piece of wood of a kind best adapted to the purpose; then its insulation is raised and the life of the wood is prolonged by a thorough impregnation with minerallac compound. This is an unexcelled wood preserver. Its effect in increasing the insulation is remarkable. Insulators made of materials similar to these in the combined pin and insulator all in one solid piece have been steadily in service without breakdown or jump-over on 4,000, 9,000 and 12,000 volt high tension lines for some years in the plant of the Commonwealth Edison Co., of Chicago, where the manufacturers, the Minerallac Electric Co., placed them for a trial. Some of the earliest installations made have been in actual service as much as eight years, and show no deterioration in insulating qualities, nor any tendency to crack or split.



(patent applied for)

The New Mineralac Combined Insulator and Pin.


The Minerallac Electric Co., having given this specialty a thorough experimental try-out under practical conditions in high tension work, is now ready to push the distribution in this field and also in the telephone field. It is apparent that they can be produced and distributed at a low cost, as they are turned out rapidly and impregnated in a short time in large quantity, and can be cheaply packed and distributed without breakage.

These insulators can go up against the small boy with a stone in his hand or a sling shot and stand for all the mischief he wants to produce. If any hunter going along the highway in the fall hates to carry back his gun with the last cartridge unexploded, and lets drive at the telephone line, well and good. This insulator will take care of anything he sends and be ready for the next one, and it will take more lead pellets than the average shotgun will throw into an object of this size 30 feet distant to make a conductor of it. Let the lineman drop a few off a pole and he can go down and get them, ready to put into service in a few seconds and last for years.

As far as mechanical strength goes, experience has already shown that it will stand up without breakage under conditions more severe than the heaviest toll line construction. There is no joint or groove between the insulator and supporting sections, all the natural toughness of the wood being available to resist mechanical line stresses.

The Minerallac Electric Co. reports that it is going to have an exhibition and demonstration at the National Independent Telephone convention, Room 367, next week, which will prove all these points and substantiate the strongest claims which can be made for the several qualities and construction economies obtained by the use of this device. It is sure to be one of the hid features of the convention and those who do not attend will likely make it the subject of their first inquiries of their state delegates upon their return home, or of the manufacturers, Minerallac Electric Co., Chicago, Ill.


Keywords:Minerallac Electric Company : Unity Insulator
Researcher notes: 
Supplemental information: 
Researcher:Elton Gish / Bob Stahr
Date completed:August 14, 2010 by: Bob Stahr;