Method of manufacturing electrical cable, and resulting product, with reduced required installation pulling force
View Patent ↗Disclosed is type THHN cable having a reduced surface coefficient of friction, and the method of manufacture thereof, in which the central conductor core and insulating layer are surrounded by a nylon sheath. A high viscosity, high molecular weight silicone based pulling lubricant for THHN cable, or alternatively, erucamide or stearyl erucamide for small THHN gauge wire, is incorporated, by alternate methods, with the nylon material from which the outer sheath is extruded, and is effective to reduce the required pulling force on the cable during installation.
1. A thermoplastic high heat-resistant nylon-coated (THHN) electrical cable having reduced installation pulling force through a polyvinyl chloride (PVC) conduit setup, the THHN electrical cable comprising:
at least one conductor capable of carrying an electrical current through the THHN electrical cable, wherein the conductor is formed at least in part from copper; and,
a sheath for protecting the conductor, wherein the sheath comprises:
an insulating layer surrounding the conductor and providing electrical insulation to the conductor, wherein the insulating layer is formed at least in part from extruded polyvinyl chloride (PVC); and,
an outer layer surrounding the insulating layer, wherein the outer layer further comprises;
an extruded nylon component;
a pulling lubricant incorporated in the extruded nylon component that aids in reducing the installation pulling force as the THHN electrical cable is pulled through a PVC conduit setup; and wherein,
the pulling lubricant is silicone based; and
the pulling lubricant is present in at least a portion of the outer layer at a concentration of between about 4% and about 14% by weight; and further wherein,
the outer layer is both resistant to heat, moisture, oil and gasoline, and provides the THHN electrical cable with the physical characteristic of having an average coefficient of friction against an interior surface of a PVC conduit setup of less than about 0.25.
2. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the silicone based pulling lubricant comprises a high molecular weight silicone based pulling lubricant.
3. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 2 , wherein the THHN electrical cable has the physical characteristic of having an average coefficient of friction against an interior surface of a PVC conduit setup of less than about 0.2.
4. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 2 , wherein the THHN electrical cable has the physical characteristic of having an average coefficient of friction against an interior surface of a PVC conduit of between about 0.125 and about 0.2.
5. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 2 , wherein the THHN electrical cable has the physical characteristic of having an average coefficient of friction against an interior surface of a PVC conduit of less than about 0.15.
6. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the silicone based pulling lubricant comprises a low molecular weight silicone based pulling lubricant.
7. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the at least one conductor comprises a plurality of grouped conductors.
8. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the at least one conductor is a large gauge conductor.
9. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 8 , wherein the at least one conductor comprises an AWG 4/0 conductor.
10. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the THHN electrical cable has a round profile.
11. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the pulling lubricant is present in at least a portion of the outer layer at a concentration of between about 5% and about 7% by weight.
12. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the pulling lubricant is present in at least a portion of the outer layer at a concentration of between about 7% and about 9% by weight.
13. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the pulling lubricant is present in at least a portion of the outer layer at a concentration of between about 7% and about 14% by weight.
14. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the pulling lubricant is present in at least a portion of the outer layer at a concentration of between about 9% and about 14% by weight.
15. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the pulling lubricant is present in at least a portion of the outer layer at a concentration of about 9% by weight.
16. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the THHN electrical cable is rated for use in dry locations at temperatures not to exceed 90° C.
17. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the THHN electrical cable is rated to carry current at voltages not to exceed 600 Volts.
18. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 1 , wherein the PVC conduit setup includes at least two 90° bends.
19. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 18 , wherein the PVC conduit setup includes a first straight section of conduit connected to a first one of the 90° bends, a second straight section of conduit connected between the first one of the 90° bends and a second one of the 90° bends, and a third straight section of conduit connected to the second one of the 90° bends.
20. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 19 , wherein the first straight section of the conduit is about 30′ long, the second straight section of the conduit is about 5′ long, and the third straight section of the conduit is about 10′ long.
21. A thermoplastic high heat-resistant nylon-coated (THHN) electrical cable having reduced installation pulling force through a polyvinyl chloride (PVC) conduit setup, the THHN electrical cable comprising:
at least one conductor capable of carrying an electrical current through the THHN electrical cable, wherein the conductor is formed at least in part from at least one metal; and,
a sheath for protecting the conductor, wherein the sheath comprises:
an insulating layer surrounding the conductor and providing electrical insulation to the conductor, wherein the insulating layer is formed at least in part from extruded polyvinyl chloride (PVC); and,
an outer layer surrounding the insulating layer, wherein the outer layer further comprises;
an extruded nylon component;
a pulling lubricant incorporated in the extruded nylon component that aids in reducing the installation pulling force as the THHN electrical cable is pulled through a conduit; and wherein,
the pulling lubricant is silicone based;
the pulling lubricant is present in at least a portion of the outer layer at a concentration of between about 4% and about 14% by weight; and wherein,
the pulling lubricant is permeable through the nylon component after the nylon component has been extruded and can be squeezed therefrom when the THHN electrical cable is pulled through a PVC conduit; and further wherein,
the outer layer is both resistant to heat, moisture, oil and gasoline, and provides the THHN electrical cable with the physical characteristic of having an average coefficient of friction against an interior surface of a PVC conduit of less than about 0.25.
22. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 21 , wherein the PVC conduit setup includes at least two 90° bends.
23. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 22 , wherein the PVC conduit setup includes a first straight section of conduit connected to a first one of the 90° bends, a second straight section of conduit connected between the first one of the 90° bends and a second one of the 90° bends, and a third straight section of conduit connected to the second one of the 90° bends.
24. The thermoplastic high heat-resistant nylon-coated (THHN) electrical cable of claim 23 , wherein the first straight section of the conduit is about 30′ long, the second straight section of the conduit is about 5′ long, and the third straight section of the conduit is about 10′ long.