US 2004004 A
Description (OCR text may contain errors)
Original Filed April 1, 1933 Inventor: Home- G. Knocler'a y (4564 His Attorney.
Patented June 4, 1935' PATENT OFFICE WEATHERPROOF ARMORED CABLE Homer G. Knoderer, Fairfield, Conn, assignor to General Electric Company, a corporation of New York Application April 1, 1933, Serial No. 663,974 Renewed February 8, 1935 4 Claims.
My invention relates to an improved weatherproof armored cable;
In connecting a house wiring system to the power supply lines, it has been a common practice to use rigid conduit extending up the side of the house and to pass the conductors through it. The use of rigid conduit produces an expensive installation and in addition such an installation has proven to be one from which electric current may readily be taken in an unauthorized manner.
The object of my invention is to provide an improved weatherproof armored cable of relatively lost cost of manufacture, easy to install, resistant to the effects of atmospheric conditions and practically theftproof.
What I consider to be novel and my invention will be better understood by reference to the following specification and appended claims, when considered in connection with the accompanying drawing.
In the accompanying drawing, Fig. 1 is a plan view of my electric cable with the layers of in sulation cut away to expose the layers beneath and Fig. 2 is a sectional view of the cable.
Referring to the drawing, two conductors l0 and II consist of strands l2 and I 3 of relatively large diameter wound together spirally to form a flexible core. The conductors l0, H are provided with the usual layer of rubber insulation l4, l5 covered by a cotton braid l6 and II. The cotton braids l6 and I1 may be impregnated with colored wax to distinguish them; one may be impregnated with a red waxand the other with a black'wax. Over the combined conductors l0 and II withtheir insulation is wound a paper strip l8. This paper strip is used to secure the conductors together and provide a smooth continuous surface over them. It may be omitted in some instances if found desirable. The conductors Ill and II as shown are laid longitudinally side by side but they may be wound together spirally if desired to increase the flexibility of the cable. A bare conductor I5 is wound spirally around the conductors Ill and l I. It consists of a number of strands 20 of relatively small diameter. The strands 20 are evenly distributed about the combined surface of the conductors l0 and II and are sufliciently great in number to provide a practically continuous surface. The diameter of strands 20 is such, preferably, that the combined cross section of all of the strands forming the conductor I9 is equal to the cross section of each of the conductors l0 and II.
spaced relation to each other. In place of armor is wound spirally. This layer 2| serves also as a However, it is not necessary that the cross section of conductor 19 be exactly equal to the cross section of conductors l0 and H. It may be-somewhat less as the greater surface of conductor l9 provides a relatively large area for the dissipa- 5 tion of heat and with the same current density in the conductor is as is in conductors l0 and H, the temperature rise due to the flow of current will be less. Therefore, for the same temperature rise the cross section of the conductor is may be somewhat smaller than the cross section of each of the conductors l0 and H About conductor IS an armor 2i is wound consisting of a half round strip of metal wound spirally with the turns in 2! an interlocked armor may be used. However, this half round armor with'the turns spaced apart provides somewhat greater flexibility with sumcient mechanical protection for the conductors and is also of lighter weight as compared with an interlocked armor. Armor 2! is wound in the opposite direction to the strands 20 of conductor l9. This provides a greater flexibility. Also, it is easier to remove than if the two were wound in the same direction. Over the armor a layer 22 of rubber filled tape is wound spirally. Over the layer a layer 23 of waterproofing compound, such as an asphaltic compound, is applied. The asphaltic compound serves to provide the primary source of weather-proofing for the cable. The layer 22 of rubber fllled tape serves as a separator between the layer 23 of asphaltic compound and the armor 2| and bare conductor l9. In place of the rubber filled tape 22, a covering of fibrous material may be used to serve as a separator. The rubber filled tape however provides an additional measure of weatherproofing for the cable. Over the layer of asphaltic compound a layer of rubber filled tape 24 separator between the asphaltic compound and any additional covering applied to the cable. An overall cotton braid 25 is provided which is of relatively heavy materialand is impregnated with a flameproof saturant such as stearin pitch. To connect the cable to the power conductors or to 'a service switch in a house, the ends of the conductors are prepared by first cutting and removing the braid 25 and the two tapes 22 and 24. This is a very simple operation. Armor 2| is then removed by unwinding it as far back from the end as desired and cutting the strip with a pair of pliers or other tool. Strands 28 are then unwound back to where the armor has been tor.
nection from a pole on which a transformer is limited to a cable consisting of two insulated conductors and one bare conductor but is equally applicable to any cable having one or more insulated conductors surrounded by a bare conduc- This cable may also be used to bring a consupported to the house as well as to make a connection to the separate conductors as usually brought from the pole to the side of the house. This is made possible by the relatively light weight of the cable. Such an arrangement makes the cable weatherproof from-its point of connection to the supply at the pole to the pointof its entrance into the house.
It is to be noted that in my improved cable the weatherproofing compound is applied only outside of the armor to facilitate the stripping of the conductors. Also, a separator is provided between the weatherproofing compound and the armor in order to prevent the weatherproofing compound, adhering to the armor and interfering with the grounding of the armor. Additional protection of the conductors against use by unauthofized persons is provided by winding an uninsulated conductor around one or more insulated conductors and so completely surround-- ing the conductor or conductors that it is practically impossible to make contact with the in-. ner conductors without contacting with the bare conductors. This bare conductor is also one of the supply conductors and is secured in place by an armor which in addition provides mechanical protection for the conductors.
From the foregoing it will be seen that an im proved weatherproof armored cable is provided which is relatively easy to install, which is thoroughly protected from atmospheric conditions,
mechanically protected to provide the necessary strength, and in addition is provided with means to prevent the theft of electric current therefrom. Also, the arrangement of the bare conductor and the half round armor strip reduces the size of the cable as well as the amount of material necessary, consequently reducing the cost of manufacture of the cable.
What I claim as new and desire to secure by Letters Patent of the United States, is,-
1. In an electric cable, an electric conductor, insulating material surrounding said conductor, a second conductor consisting of strands spirally wound about said conductor and insulation, a metallic armor wound around and in contact with said second conductor, a tape of fibrous material covering said armor, a weatherproofing compound covering said tape, and an overall braid of fibrous material impregnated with a fiameproof material.
2. In an electric cable, a conducton insulation surrounding said conductor, a second conductor consisting of strands wound around said first conductor and insulation, an armor surrounding said second conductor andin contact therewith, an overlapping wrap of rubber filled fabric tape covering said armor, a layer of asphaltic compound over said tape, a second wrap of rubber filled tape over said layer of asphaltic compound and an overall braid of fibrous material impregnated with a fiameproofing compound. 1
3. In an electric cable, a plurality ofconductors, insulation surrounding said conductors, a conductor consisting of strands wound around said conductors and insulation, an armor surrounding said last mentioned conductorv and in contact therewith, an overlapping wrap of rubber filled fabric tape covering said armor, a layer of asphaltic compound over said tape, a second wrap of rubber filled tape over said layer of asphaltic compound, and an overall braid of fibrous material impregnated with a flameproofing compound.
4. In an electric cable, a plurality of conductors, insulation surrounding each conductor, a paper strip wound spirally over said conductors and insulation, a conductor consisting of strands wound over said paper strip, an armor surrounding said last mentioned conductor and in con- I