Non-circular electrical cable having a reduced pulling force
In various embodiments, a non-circular electrical cable having a reduced pulling force attributable to the exterior surface of an outer sheath, and method of producing the same is provided. In various embodiments, an outer sheath of the cable may comprise a first and second sheath layer, the second sheath layer being located external to the first sheath layer, and comprising a nylon material configured to reduce the pulling force necessary for installing the cable. In various embodiments, the first sheath layer may be extruded using a tube extrusion method into a substantially circular shape, and the second sheath layer may be extruded using a pressure extrusion methods onto the exterior surface of the first sheath layer while maintaining the at least substantially circular shape of the sheath. The sheath may then be pulled onto the surface of a plurality of conductors to form the non-circular electrical cable.
1. A process for producing non-circular electrical cable, wherein the non-circular electrical cable comprises one or more conductors arranged in a non-circular arrangement and an exterior sheath comprising a first sheath layer and a second sheath layer, said process comprising steps for:
advancing the one or more conductors through an extruder head;
extruding a first sheath layer comprising a plastic material around the one or more conductors, wherein the first sheath layer is initially extruded in a substantially circular shape having an inner surface and an exterior surface and at least a portion of the inner surface thereof is spaced from the one or more conductors;
extruding a second sheath layer comprising a nylon material around an exterior surface of the first sheath layer, wherein the second sheath layer has a different polymer composition than the first sheath layer;
applying a negative pressure to the interior surface of the first sheath layer, thereby pulling the first sheath layer and second sheath layer onto the one or more conductors and into a non-circular shape having a cross section substantially similar to the combined cross section of the one or more conductors; and
cooling the first and second sheath layers.
2. The process of claim 1 , wherein the second sheath layer additionally comprises a lubricant for decreasing the pulling force of the non-circular electrical cable.
3. The process of claim 2 , wherein the lubricant comprises a silicon-based lubricant.
4. The process of claim 2 , comprising the additional step of combining the nylon material and lubricant prior to extruding the second sheath layer.
5. The process of claim 1 , wherein the first sheath layer comprises a poly-vinyl chloride material.
6. The process of claim 5 , wherein the first sheath layer comprises a foamed poly-vinyl chloride material.
7. The process of claim 5 , wherein the first sheath layer comprises a re-grind poly-vinyl chloride material.
8. The process of claim 1 , wherein a mechanical bond is formed between the first sheath layer and the second sheath layer.
9. The process of claim 8 , wherein the mechanical bond comprises a heat bond.
10. The process of claim 1 , wherein the one or more conductors comprises a first conductor, a second conductor and a ground wire, wherein the first conductor has a first insulative coating on an external surface of the first conductor and the second conductor has a second insulative coating on an external surface of the second conductor, and wherein the first conductor, second conductor, and ground wire are arranged in a substantially flat configuration.