US1798486A - Electrical conductor - Google Patents

Description

March 31, 1931.

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i? f5 19 my j( M7125? @Y l ATTORNEY D. H. MURPHY ELECTRICAL CONDUCTOR Patented Mar. 31, 1931 UNITED STATES PATENT OFFICE y DANIEL H. MURPHY, OF WEST' HARTFORD, CONNECTICUT, ASSIGNOR, 'BY MESNE AS- SIGNMENTS, TO NATIONAL ELECTRIC PRODUCTS CORPORATION, OF NEW YORK, N. Y.,

A CORPORATION OF DELAWARE ELECTRICAL CONDUCTOR Application filed March 15, 1928. Serial No. 261,944.

This invention relates to insulated electrical conductors, and more particularly to conductors having their outer jackets colored in a novel manner to give them a distinctive Aappearance.

It is important that Wires and cables be identified or have a distinctive appearance to distinguish one type of wire or cable from another, and also for the purpose of identifying the polarity of wires in an installation. lt has therefore been proposed heretofore to form the protecting covering upon different conductors of different colored strands. For example, it is customary to form the covering upon one of a pair of conductors of cotton yarn having the natural white color, and the covering upon the other conductor of black or other colored yarn so that the two conductors can be readily distinguished.

The desired color or distinctive appearance has been imparted to covered conductors heretofore by forming the covering of dyed yarn, but this increases the cost of the insulated conductors since the effect of the dye upon the yarn is to make it tender, thus necessitating the use of a higher grade of yarn at the st-art to make up for the reduction in tensile strength due to the dyeing process.

In many constructions it is desirable to apply to the jacket of an insulated conductor or cable a coating of a protecting compound which will completely conceal the original -color that may have been given the jacket, in

which case the use of dyed yarn obviously will not impart the desired distinctive appearance to the finished product.

Having in mind the foregoing, the present Ainvention relates to a novel construction whereby any desired color is imparted to a non-metallic sheathed conductor or cable which has been treated with a protective compound.

In carrying out the present invention, a coating of coloring matter, such as any good grade of paint that will permanently adhere to the underl ing surface, is applied to the conductor jac et which has been previously treated with a protecting compound. Then over this coloring matter is placed a transparent film of wax-like material which protects the coat of coloring matter without obscuring the color. The wax material protects the coloring matter from dirt, moisture and the deteriorating action of the atmosphere. It also prevents the color from rubbing off and marking adjacent objects such as the wall or ceiling to which the conductor may be secured. Furthermore, the wax film imparts a slick finish7 to the conductor which makes it clean to handle and easy to draw through conduits and openings during installation, and the distinctive color imparted to the conductor by the coloring matter is clearly observable through the transparent film of wax.

Through the use of the present invention the insulated conductors may be given any desired color at low cost, and a further sav ing is secured in the manufacturing cost due to the fact that uncolored yarn may be used in the construction of all conductor insulation,

thus permitting standardizations in the factory.

The various features of the invention will be best understood from the following description when read in connection with the accompanying drawings, wherein:-

Fig. l is a perspective view of an insulated conductor embodying the features of the present invention, the different coatings be ing shown on different portions thereof;

Fig. 2 is a perspective View of a cable provided with a pair of different colored insulated conductors; and

Fig. 3 is a longitudinal sectional View through mechanism for applying a film of wax to the colored conductor.

The present invention may be employed to impart any desired color or distinctive appearance to insulated Wires, cables and protecting tubing, and may be employed upon insulating jackets that are woven, braided, wrapped or otherwise constructed.

The insulated electrical conductor illustrated in the drawing is formed of a conductor wire 10 about which is provided a jacket 1l of rubber or other suitable material, and over the jacket 1l is provided a protecting covering 12 which is shown as braided,

l but as above constructed.'

pointed out may be otherwise ta long period of timeso that it will not become hard'and brittle. While various sticky materials may 13, stearin pltch is peculiarly well adapted be used to lform the coating tinctive color imparted to the4 insulated conductor by the coatin 14 maybe clearly observed through the t in transparent film 15.

In the cable shown in Fig. 2 each of the insulated conductors and 21 is similar to the colored-conductor-of Fig. 1` except that the conductor 20 is colored dark while the conlductor 21 is given a lighter colorv in order that their polarity ma be readily determined. `About the con uctors 20'and 21 is wound the insulating material 22, and these conductors are enclosed in an outer jacket 23 for this purpose as it is fire-repellent to a high which if desired may be colored in accorddegree, and retains its plastic, rubbery character over a long period of time, while it is suilficientlyadhesive to firmly adhere to the surface to which it is applied.

After the stearin pitch or other protecting compound 13 has been dried or otherwise treated to render it dry and firm upon the conductor jacket, the color coating is applied. The coloring matter used may e ordinary paint or pigment which will not become brittle when dry 'and crack under the 'iiexing of the cable and it may be applied to the covered conductor by passingthel conductor through a bath of the coloring matter and then wiping off the excess coloring, but care should be used in controlling the speed of the cable through the tank, and

also the thickness of the coloring fluid, to

" secure a satisfactory coatin which will not be too scant, or too thick an gobby.

After the coating 14 upon the insulated conductor has dried, there is applied thereto,'in accordance with the present lnventlon,

a transparent film -15 of wax-like material. This film may be appliedV to the colored conductor by the mechanism shown in Fig. 3 of the drawing wherein the colored conductor 14 is shown as passing from a supply reel 16 z into a tank 17 containing' the melted paraffin or other wax-'like material. The tank 17 maybe heated by the burners 18 and as the conductor 14 leaves the tank it passes U' which it is placed, and it also increases the life of the underlying coatings by protecting them from the atmosphere.v

' The wax coating 15 when applied in the form 'of a thin lm will not appreciablydecrease the flame retarding properties of the stearin pitch 13, for, although the wax material is combustible, the very small amount of this material required ,to form the desired film will not be sufficient to su port combust1on, and it will be understoo that the disance with the present invention.

1. In the art of electrical insulation, a jacket for an velectrical conductor formed of interlocked strands of insulating material and having applied to the acket three distinct layers of coating material placed one over the other in an unmixed condition comprising, a iame-retarding coating of stearinv pitch applied over the interlocked strands, a coating of paint applied over the layer of stearin pitch, and a transparent film of Wax applied over the paint so that the color of the paint may be seen through the protecting lilm of wax;

2. In the art of electrical insulation, a iiexible jacket for an electrical conductor formed vof the jackets and so that the color of the second coating may be distinctly seen through said film.

3. In the art of electrical insulation, a cable formed of a plurality of insulated 'conductors each having a iiexible jacket of insulating material over which is applied. three distinct layers of coating material placed one over the other in an unmixed condition, and comprising a iame-retal'ding coating of lstearin pitch applied over each jacket, a different color coating of paint applied over each pitch covered jacket to give each jacket a different color, a film of transparent wax applied over each coating of paint in nonpenetrating relation with the vunderlyin jacket and so that the color of the secon coating upon each jacket may be distinctly seen through said film, and an outer jacket enclosing the differentcolored conductors. In testimony whereof, I have signed my name to this specification.

DANIEL H. MURPHY.

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