Patent Publication Number: US-6210206-B1

Title: Safety shield spiking tool and method for spiking high voltage power lines

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to spiking tools for spiking underground power lines to determine if the power lines are hot and, in particular, to a spiking tool and method of spiking a power line which shields the spiking tool operator from the flame and heat emitted when a hot power line is spiked. 
     During the construction of shopping malls, industrial complexes, commercial buildings, and similar relatively large building projects, new or existing, buried or underground high voltage power lines have to be tapped into or spliced to provide electrical services to the project. Typically, there will be several different tubular conduits closely grouped together within the trench that each contain a different high voltage power line or cable. Once a length of one of the power lines to be tapped for the project has been exposed, by removing a section of one of the tubular conduits from about the power line, the power line must be checked to determine if the electrical power to the power line has actually been turned off prior to working with the power line to make the tap. Otherwise, if the electrical power to the power line has not been turned off, anyone working with the power line to make a tap would most likely be seriously injured if not killed. 
     Typically, the power line is tested to determine if the electrical power to the power line has been turned off by spiking the power line with a spiking clamp (such as, a spiking clamp made by Hastings of Hastings, Mich.). The spiking clamp has a threaded spike with a pointed end that is used to penetrate the insulating casing of the power line and make contact with the wiring within insulating casing of the power line. The threaded spike is grounded and an eye on the second end of the threaded spike is turned with a shotgun stick (such as, a shotgun stick sold by Hastings of Hastings, Mich.) to cause the spike to penetrate the insulating casing and make contact with the wiring within the insulating casing. If the power line is hot (the electrical power to the power line has not been turned off) the contact of the spike of the spiking clamp with the wiring of the power line normally causes an eruption of hot flame from the power line at the location of the spike. Although the use of a shotgun stick is intended to protect the workers when the spike makes contact with a hot line, the workers are not shielded by the spiking clamp or shotgun stick and the operator of the shotgun stick or other workers close by can be injured by the flame and heat caused by spiking the power line. Thus, although spiking clamps and shotgun sticks have been in use for many years, there has remained a need to protect the shotgun operator and other workers from the flame and heat of a spiking operation when the power line is hot. 
     SUMMARY OF THE INVENTION 
     The spiking tool of the present invention for spiking high voltage underground power lines includes a safety shield to protect the operator of a shotgun stick from the flame and heat emitted when a hot power line is spiked. 
     A first embodiment of the spiking tool of the present invention includes a tubular sleeve for encasing a length of power line and a spiking assembly. The tubular sleeve shields the operator from the flame and heat emitted when a hot power line is spiked. The tubular sleeve has: an internal diameter greater than an external diameter of a power line to be encased within the tubular sleeve for spiking; a longitudinally extending slot therein extending for the length of the tubular sleeve through which a power line can be introduced into the tubular sleeve; and, preferably, is fire resistant and high temperature resistant. The spiking assembly includes a spike, made of an electrically conductive material, with a pointed first end for penetrating the insulating casing of and making contact with wiring within a power line housed within the tubular sleeve. The spiking assembly also includes an assembly mount for mounting the spike on a central portion of the tubular sleeve with the spike passing through a sidewall of the tubular sleeve, the pointed first end of the spike located within the tubular sleeve, and the longitudinal axis of the spike out of alignment with the longitudinally extending slot of the tubular sleeve so that the power line is supported on and by the inside of the tubular sleeve when it is being spiked. The assembly mount also has a means for moving the spike to penetrate the insulating casing of and make contact with wiring within a power line housed within the tubular sleeve and an electrically conductive means for connecting the spike to a ground. 
     A second embodiment of the spiking tool of the present invention includes a shield which is mounted on a conventional shotgun stick that is used for turning the spike of a power line spiking assembly. As discussed above in the background of the invention, typically, a shotgun stick has an elongated shaft with a handle adjacent a first end to be held by a tool operator and a hook at a second end for engaging the eye of a spike of a spiking assembly. The shield has a plate, preferably a disk, extending perpendicular to a longitudinal axis of and outward from the elongated shaft of the shotgun stick for a radial distance sufficient to shield an operator of the shotgun stick from the flame and heat when a hot power line is spiked and is mounted on the elongated shaft of the shotgun stick intermediate the first and second ends of the shaft to protect a tool operator from heat and flame when a hot power line is spiked. The shield plate is clear so that the tool operator can see a spiking assembly and power line through the shield and colored to reduce the glare from a flame when a hot power line is spiked. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic cross section through a trench containing high voltage underground power lines to schematically illustrate the first embodiment of the shielded spiking tool of the present invention in use. 
     FIG. 2 is a schematic perspective view of the first embodiment of the shielded spiking tool of the present invention. 
     FIG. 3 is a schematic side view of the first embodiment of the shielded spiking tool of the present invention. 
     FIG. 4 is a schematic end view of the first embodiment of the shielded spiking tool of the present invention. 
     FIG. 5 is a schematic perspective view of the first embodiment of the shielded spiking tool of the present invention provided with tubular sleeve extensions for adjusting the length of the spiking tool shield. 
     FIG. 6 is a schematic cross section taken substantially along lines  6 — 6  of FIG. 5 to illustrate one form of latching system for securing the tubular sleeve extensions to the main tubular sleeve. 
     FIG. 7 is a schematic cross section through a trench containing high voltage underground power lines to schematically illustrate the second embodiment of the shielded spiking tool of the present invention in use. 
     FIG. 8 is a schematic side view of a shield of the spiking tool of the second embodiment of the present invention. 
     FIG. 9 is a schematic top or bottom view of the shield of FIG.  8 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 schematically shows a first embodiment  20  of the spiking tool of the present invention being used to spike an underground, high voltage power line  22 . As shown, there is a grouping of nine different conduits  24 , each containing a different high voltage power line  22 , in a trench. Typically, the conduits  24  are positioned and supported on spacers  26 , but are located in very close proximity to one another so that it can be quite difficult to work on a power line  22  in one of the conduits within the grouping of conduits. As shown, a high voltage power line  22  in a centrally located conduit is be spiked and to do that one or more blocks of wood or other spacers  28  have been used to spread apart two of the upper conduits  24  to gain access to the conduit and power line with the spiking tool  20  and a conventional shotgun stick  30 , such as a Hastings shotgun stick sold by Hastings of Hastings, Mich. While the slot in the spiking tool  20  is shown opening to the right in the FIG. 1, the spiking tool can also be turned around so that the slot in the spiking tool would open to the left. 
     As shown in FIGS. 2-4, the first embodiment  20  of the spiking tool of the present invention includes a tubular sleeve  32  for encasing a length of power line  22  and a spiking assembly  34 . The tubular sleeve  32  has a length sufficient to shield the operator from the flame and heat emitted when a hot power line  22  is spiked and is, typically, between about 8 inches and about 38 inches long, preferably, between about 14 inches and about 18 inches long. The tubular sleeve  32  can be made of either a conductive or nonconductive material, such as but not limited to, a glass fiber reinforced plastic, an ABS plastic, stainless steel or aluminum, and may be resilient. Preferably, the tubular sleeve  32  is made of a fire and heat resistant, non-conductive material and/or the internal surface of the tubular sleeve  32  is coated, coating  36 , with a commercially available, fire resistant and/or retardant, high temperature resistant material, such as but not limited to, commercially available silica containing coatings or commercially available coatings containing heat expandable graphite flakes such as coatings disclosed in U.S. Pat. No. 3,574,644. Where a conductive material is used for the tubular sleeve, preferably, the interior surface of the sleeve is coated with a non-conductive material. While the tubular sleeve  32  preferably is a slotted, elongated hollow cylinder with a circular cross section, the tubular sleeve can be a slotted elongated sleeve having a cross section other than circular, such as but not limited to a flat oval, square or rectangular cross section. 
     The power lines or primary wires  22  spiked are typically about 1 inch to about 5 inches or greater in diameter. The tubular sleeve  32  has an internal diameter greater than the external diameter of a power line  22  to be encased within the tubular sleeve for spiking. 
     The tubular sleeve  32  has a longitudinally extending slot  38  therein, extending for the entire length of the tubular sleeve  32 , through which a power line  22  can be introduced into the tubular sleeve. The longitudinally extending slot  38  normally has a width greater than the external diameter of the power line  22  to be encased within the tubular sleeve  32  so that a length of the power line can be easily introduced into the tubular sleeve  32 . However, when the tubular sleeve  32  is made of a resilient material, the width of the slot  38  can be less than the external diameter of the power line  22  to be encased within the tubular sleeve  32  and the lateral edges of the slot  38  can be spread apart to permit the passage of the power line through the slot and into the tubular sleeve. After the power line  22  has been passed through the slot  38 , the resilience of the tubular sleeve  32  will again reduce the width of the slot  38  to more completely encase the power line  22  within the tubular sleeve. 
     The spiking assembly  34  of the spiking tool  20  includes a spike  40 , made of an electrically conductive material, such as but not limited to aluminum. The spike  40  has a pointed first end  42  for penetrating the insulating casing of and making contact with wiring within a power line  22  housed within the tubular sleeve  32 . The spiking assembly  34  also includes an assembly mount  44  for mounting the spike  40  on a central portion of the tubular sleeve  32  (preferably midway between the ends of the tubular sleeve) with the spike  40  passing through a sidewall of the tubular sleeve, the pointed first end  42  of the spike located within the tubular sleeve, and the longitudinal axis of the spike  40  out of alignment with the longitudinally extending slot  38  of the tubular sleeve so that the power line  22  is supported on and by the inside of the tubular sleeve  32  when it is being spiked. The assembly mount  44  also has a means for moving the spike  40  in the direction of its longitudinal axis to penetrate the insulating casing of and make contact with wiring within a power line  22  housed within the tubular sleeve. In a preferred form of the invention, the spike  40  and the assembly mount  44  are both threaded and the spike  40  is provided with an eye  46  at its second end by which the spike  40  can be turned in the assembly mount  44  to move the spike  40  in or out in the direction of its longitudinal axis. The spiking assembly  34  also includes an electrically conductive means  48 , e.g. a cable typically about 8 feet long connected to the assembly mount  44  at one end and to a grounding rod at the other end, for connecting the spike  40  to a ground. 
     FIGS. 5 and 6 show the spiking tool  20  provided with a pair of tubular sleeve extensions  50  which are slidably mounted on the tubular sleeve  32  and can be used to adjust the length of the tubular sleeve shield encasing a power line  22 . As shown, each of the tubular sleeve extensions  50  is provided with a series of longitudinally aligned holes  52  which are centered over a longitudinally extending groove  54  in the interior surface of the tubular sleeve extension. A spring loaded push button  56  is secured to the tubular sleeve  32  at a location spaced inwardly from but near each end of the tubular sleeve  32 . The spring loaded push buttons  56  are received within the grooves  54  of the tubular sleeve extensions  50  and as the sleeve extensions are slid relative to the tubular sleeve  32 , the push buttons  56  pop into the holes  52  that are aligned with the push buttons to secure the extensions in place relative to the tubular sleeve  32 . To adjust an extension  50  in or out, the operator merely has to depress the push button  56  out of a hole  52 , slide the extension in or out, and let the spring loaded push button pop into another hole  52  when the extension is located where the operator wants the extension to get the desired tubular sleeve shield length. With the push buttons  56  located within the grooves  54 , the slots  58  in the tubular sleeve extensions are properly aligned with the slot  38  in the tubular sleeve  32  so that a power line  22  can be passed through the slot  38  and slots  58  into the tubular sleeve  32  and the tubular sleeve extensions  50 . While two tubular sleeve extensions  50  are shown, one or two tubular sleeve extensions can be used. The number of holes  52 , the spacing of the holes  52  and the lengths of the tubular sleeve extensions  50  can vary as required. In addition, a latching means other than the spring loaded push buttons  56  can also be used to locate and retain the tubular sleeve extensions relative to the tubular sleeve  32 . 
     The method of using spiking tool  20  to spike a high voltage, underground power line  22  includes: removing a section of a conduit  24  to expose a length of a power line  22 ; passing the length of power line  22  through the longitudinal slot  38  of the tubular sleeve  32  so that the length of power line  22  is encased within the tubular sleeve  32 ; centering the length of power line  22  beneath the spike  40  of the spiking assembly  34 ; grounding the spiking assembly; connecting the shotgun stick  30  to the eye  46  of the spike  40 ; and turning the spike  40  with the shotgun stick  30  to drive the pointed first end  42  of the spike  40  through the insulating casing of the power line and into contact with wiring within the power line to determine if the power line is hot. 
     FIG. 7 schematically shows a second embodiment  120  of the spiking tool of the present invention being used to spike an underground, high voltage power line  22 . As shown, there is a grouping of nine different conduits  24 , each containing a different high voltage power line  22 , in a trench. As discussed above in connection with the first embodiment, typically, the conduits  24  are positioned and supported on spacers  26 , but are located in very close proximity to one another so that it can be quite difficult to work on a power line  22  in one of the conduits within the grouping of conduits. As shown, a high voltage power line  22  in a centrally located conduit is be spiked and to do that one or more blocks of wood or other spacers  28  have been used to spread apart two of the upper conduits  24  to gain access to the conduit and power line with the spiking tool  20  and a conventional shotgun stick  124 , such as but not limited to a Hastings shotgun stick sold by Hastings of Hastings, Mich. 
     As shown in FIGS. 7-9, the second embodiment  120  of the spiking tool of the present invention includes a shield  122  which is mounted on a conventional shotgun stick  124  that is used for turning the spike  126  of a grounded power line spiking clamp  128 . The shotgun stick  124  has an elongated shaft  130 , e.g. about 6 feet to about 8 feet long, with a handle  132  adjacent a first end to be held by a tool operator and a hook  134  at a second end for engaging the eye  136  of the spike  126  of the spiking clamp  128 . The shield  122  has a plate  138 , preferably a disk about ¼ inch in thickness made of epoxyglass, a plastic (preferably heat resistant) or a similar material, extending perpendicular to a longitudinal axis of and outward from the elongated shaft  130  of the shotgun stick  124  a distance sufficient to shield the tool operator from the flame and heat emitted when a hot power line is spiked, e.g. typically, a radial distance of about 5 to about 8 inches or greater from the circumferential surface of the shaft and for certain applications a radial distance of about 12 inches or greater from the circumferential surface of the shaft of the shotgun stick  124 . The shield  122  has a collar  140  which can be tightened about the shaft  130  of the shotgun stick  124  and is mounted on the elongated shaft  130  of the shotgun stick intermediate the first and second ends of the shaft (preferably, adjacent the second end of the shaft near the spiking clamp) to protect a tool operator from heat and flame when a hot power line is spiked. The shield plate  122  is clear so that the tool operator can see a spiking clamp  128  and power line  22  through the shield plate and colored, e.g. a smoky clear, to reduce the glare from a flame when a hot power line is spiked. 
     In describing the invention, certain embodiments have been used to illustrate the invention and the practices thereof. However, the invention is not limited to these specific embodiments as other embodiments and modifications within the spirit of the invention will readily occur to those skilled in the art on reading this specification. Thus, the invention is not intended to be limited to the specific embodiments disclosed, but is to be limited only by the claims appended hereto.