Electricity: conductors and insulators – Underground
Reexamination Certificate
2002-06-26
2004-11-30
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Underground
C174S039000, C174S068300, C174S068300, C174S02500C
Reexamination Certificate
active
06825412
ABSTRACT:
TECHNICAL FIELD
The present invention relates to systems for terminating underground utility locator or trace wires. The invention relates more particularly to a method and device for terminating an underground utility locator wire that reduces the risk of signal bleed or transfer, protects the locator wire from damage, and reduces the amount of labor required for installation.
BACKGROUND OF THE INVENTION
It is known in the art to utilize trace or locator wires to mark the location of underground utility constructions such as water pipes, gas lines, and the like. The purpose of such locator wires is to provide a way to locate buried utility constructions, particularly in the case of non-electrically conductive utility constructions, by detecting a signal passed through the locator wire. Current utility construction practices include placement of an insulated locator wire in a trench containing, for example, a waterline or gas main. Commonly, non-electric grade insulated 12 gauge or 14 gauge wire is utilized. By connecting a line location transmitting device to the locator wire, a line location receiver may detect the signal induced, allowing easy location of an underground system such as a water line or gas main from the surface without need for random digging. This method is utilized by many utility companies to facilitate construction and/or excavation activities, i.e. to allow construction and/or repair work without fear of rupturing existing water lines or gas mains.
A locator wire must be terminated in some fashion. Current industry practices include connecting the locator wire to existing structures, such as, for example, fire hydrants or gate valves. Another common practice is to extend the locator wire above ground and directly attach it to a utility component. Yet another currently employed practice is to connect the locator wire to a short section of electrical ground rod and embed the rod in a concrete pad.
Disadvantageously, all of the above methods allow some level of signal bleed and/or signal transfer from the locator wire to adjacent utility constructions. Such signal bleed and/or transfer can result in difficulty in locating the buried utility construction. It is known that any signal bleed or transfer at or near the point at which a line location transmitter is connected to the locator wire will greatly reduce the distance at which the induced signal can be detected. In addition, the practice of extending the bare locator wire above ground exposes the wire to damage from, e.g., use of the utility component to which the wire is connected, mowing operations, or the like, and reduces the effective life of the locator wire. The practice of attaching the wire to a section of electrical ground rod and embedding the rod in concrete is labor intensive in the installation, and also allows signal bleed or transfer. Such signal bleed/transfer at or near the point where the line location transmitting device is connected to the trace wire greatly reduces the distance at which the induced signal may be detected.
Accordingly, there is need in the art for a method and apparatus for terminating locator wires to provide long-term usage with minimal loss of signal upon operation. There is further a need in the art for a method and apparatus for terminating locator or trace wires requiring less labor for installation than current systems.
SUMMARY OF THE INVENTION
In accordance with the purposes of the present invention as described herein, the present invention provides a device and method for terminating a locator wire, designed for use with any conventional locator wire. The present invention may be adapted for use near any known utility construction requiring locator wire, such as water lines, gas mains or lines, and the like. In one aspect, the present invention provides a device for terminating a locator wire for locating an underground utility conveyance, comprising a sheath for electrically isolating said locator wire from ground, and an electrically conductive terminal placed in electrical communication with the locator wire. Advantageously, the device of the present invention allows termination of a locator wire without need for attaching the wire to an existing utility, thereby minimizing signal bleed or transfer from the locator wire to the utility. Additionally, as will be described herein the device of the present invention eliminates the need to bring the locator wire aboveground for termination, thereby minimizing the risk of damage to the wire from incidental operations, such as mowing. Specifically, the present invention allows termination of a buried locator wire without need for bringing the wire aboveground.
In one embodiment, the sheath for electrically isolating the locator wire may be constructed as a unitary piece. In yet another embodiment, the sheath may comprise at least two interlocking members for capturing a portion of an existing structure, such as a utility construction, therebetween. Typically, the sheath will be fabricated from an electrically insulating material. Any suitable electrically insulating material may be selected, such as for example concrete, cement, plastic, polymers, rubber, or combinations thereof. The sheath may include a metallic outer rim, such as for example cast iron, to minimize risk of damage to the remaining components. However, it will be appreciated that in the case of a metallic component to the sheath, the electrically conductive terminal will be electrically isolated from any metallic component of the sheath to prevent signal bleed.
The sheath may include a recess for receiving the electrically conductive terminal, thereby maintaining the tip of the terminal below the top surface of the sheath and providing protection from incidental damage. Typically, the recess may include a cap or lid for covering the recess with the terminal received therein, thereby further protecting the terminal from incidental damage, inclement weather, and the like.
The electrically conductive terminal includes a body fabricated of an electrically conductive material, typically an electrically conductive metal such as copper, steel, galvanized steel, or aluminum. It will be appreciated that the body of the terminal may be of any desired shape, depending upon the specific installation requirements. The terminal may be placed in electrical communication with the locator wire by any conventional means, such as by use of a clamp, by wrapping the locator wire around the terminal, by soldering, or the like. The terminal may also include an integral wire tail for placing the terminal in electrical communication with the locator wire. The locator wire may be attached to the wire tail by any desired means, such as a conventional underground wire splice kit.
The terminal may be fabricated of a single metal, a combination of metals, or any suitable electrically conductive alloy. Any suitable metal possessing a high level of conductivity, but resistant to corrosion, may be used. In one embodiment of the present invention, the terminal may comprise an inner core and an outer coating wherein the inner core is fabricated from an easily detectable metal, and the outer coating is fabricated from a conductive metal. In a presently preferred embodiment, the inner core is fabricated of steel and the outer core is fabricated of copper. It will be appreciated that fabricating the terminal partially from an easily detectable metal such as steel facilitates location of the terminal in instances where the terminal is completely buried, for example using a conventional metal detector.
In another aspect of the present invention, a method for electrically isolating a locator wire for locating an underground utility conveyance is provided comprising the steps of positioning the locator wire in substantial alignment with a buried underground utility conveyance, placing an end of the locator wire in electrical communication with an electrically conductive terminal as described above, and electrically isolating the terminal, and thereby the attached locator wire, with an
King & Schickli PLLC
Lee Jinhee
Reichard Dean A.
T-Squared, Inc.
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