Simplex anti-induction wire

[Trade Journal]

Publication: The Electrical Engineer

New York, NY, United States
vol. 9, no. 107, p. 362, col. 1-2



SINCE the introduction of electric light and power circuits, and more especially since electric railways have become so common, the telephone and other delicate electric apparatus, have suffered considerably from induction troubles. Many attempts have been made to remedy this evil, and a variety of so-called anti or non-induction wires and cables have been invented with more or less satisfactory results. Recognizing the want for a thoroughly non-induction wire, the Simplex Electrical Company, of Boston, have recently brought out a wire which is specially designed for use on telephone lines, municipal signal systems, etc., and wherever a "silent" wire is required. To secure these results they have designed an arrangement by which there is secured, (1) a metallic circuit, (2) the parallelism of the conductors, and (3) placing them so that they may be close to each other and yet are kept absolutely apart, so that a short circuit is impossible.


Simplex Anti-Induction Telephone Wire.


These conditions are completely met in the wire shown in the accompanying engraving. The combination consists of a main copper conductor No. 16 B. & S. gauge, and a return wire of No. 10 galvanized iron, both wires being thoroughly insulated with the regular "Simplex" insulation. The two wires are kept close to each other, and yet always separate, by an ingenious weaving of cord formed of insulating material. As shown in the engraving, the line is entirely supported by the iron wire, thus attaining great tensile strength, and relieving the main conductor of all strain, one of the most important features being, that the main conductor is not tied anywhere, not even to the insulators. The separating cord is made of hemp, and is thoroughly saturated with insulating compound.

A telephone line composed of this wire, and about a mile long, has been in use for over a year, in Boston, from the office of the Simplex Electrical Company. It runs on the same cross-arms with heavy power lines, and no inductive effects have ever been observed. At present there is a line 1 3/4 miles long in St. Louis, running from the office of the Municipal Electric Light and Power Company to their station, and they are so well satisfied with it that they propose to extend its use. In Pittsburgh, also, there is a telephone line 10 1/2 miles long, with twelve stations along the lines of the Federal Street and Pleasant Valley Electric Railway, the line being strung on the same iron posts with the railway feeders, without a particle of induction. The Simplex company put up these lines and guarantee absolute freedom from induction. The wire is made up complete at the factory and shipped in reels, with instructions for erection, which any lineman can understand.


Keywords:Simplex Electrical Company
Researcher notes: 
Supplemental information: 
Researcher:Bob Stahr
Date completed:January 24, 2011 by: Elton Gish;