ApplicationNo. 10960901 filed on 10/08/2004
US Classes:362/431, Pole or post type support362/153.1, Pavement362/276, Condition responsive362/802, POSITION OR CONDITION RESPONSIVE SWITCH174/38, Distributing and/or combined with overhead174/45R, Towers, poles or posts361/601, For electrical power distribution systems and devices439/474INCLUDING OVERSTRESS PREVENTING MEANS
ExaminersPrimary: Quach-Lee, Y. My
Attorney, Agent or Firm
Foreign Patent References
International ClassF21S 13/10
BACKGROUND OF THE INVENTION
This invention generally relates to outdoor lighting systems for illuminating highways or airports and the like, and is specifically concerned with an improved system of the type wherein outdoor lights are mounted on a plurality of spaced-aparttubular masts and powered by a common, underground circuit breaker.
Outdoor lighting systems for illuminating streets and highways are known in the prior art. Such lighting systems typically include a plurality of lighting units spaced along the road or highway, each of which includes an electric light that issupported on the distal end of a tubular mast whose proximal end is anchored into the ground. In some instances, the light are suspended over the street or highway by a cantilevered support member attached to the mast. In other instances, a ring ofhigh intensity lights circumscribes the distal end of the mast. In either instance, an electric power cable connects each of the spaced-apart, mast-supported lights to a common power source in the form of the output of an above-ground circuit breaker. The electric power cable for each lighting unit includes a first portion that is connected to the light source and disposed within the hollow mast, and a second portion disposed underground and connected to a power source in the form of either theaforementioned circuit breaker, or the power cable of an adjacent lighting unit. Additionally, both a fuse assembly and a lightning arrestor are disposed within the hollow end of the mast and connected between the first and second portions of theelectric cable for preventing current overloads to the light fixture, and for protecting the circuit breaker from current surges caused by lightning. To provide access to the fuse assembly and lightning arrestor, a removable panel is usually provided atthe base of the mast. Additionally, the wrenching tensile forces applied throughout the length of the cable just before the breakage thereof at the fuse assembly splices often weakens splices and other connections made with adjacent lighting units,setting the stage for further maintenance problems that are difficult to diagnose and solve.
While such prior art lighting system are widely used to illuminate streets, highways, and virtually any place where large amounts of outdoor lighting is required, the applicant has observed a number of shortcomings associated with the design ofthese systems which significantly impairs their overall usefulness.
For example, if one of the masts of such a system should be knocked down as a result of an automobile collision, the stresses applied to the cable within the mast often causes it to break at the connections made with the fuse assembly. As theseconnections are typically made by way of splices, the tension applied to the cable from the automobile collision tears the splices apart, dangerously exposing wires that are "hot". These exposed, hot wires can in turn conduct dangerous electricalcurrents through the knocked-down mast (which is typically made of a conductive metal) or even the body of the colliding car. Even if the collision causes the exposed conductors of the broken cable splice to short circuit and trip the circuit breaker,this somewhat safer result is not partially desirable, as such tripping will cut off the current flowing to all of the other mast-supported lights that are serially connected to the breaker, thus surrounding the area around the broken mast in totaldarkness if the collision occurs at night. Additionally, the wrenching tensile forces applied throughout the length of the cable just before the breakage thereof at the fuse assembly splices often weakens splices and other connections made with adjacentlighting units, setting the stage for future maintenance problems that are difficult to diagnose and solve.
Still another shortcoming of prior art lighting systems results from the positioning of the fuse assembly and lightning arrestor in the base of the hollow mast in each lighting unit. Because such masts usually have openings at their upper endsor sides for structural reasons, the interior of such masts often becomes the home of wildlife that is either potentially hostile (such as wasps, poisonous snakes, or rats) or of the type apt to build nests around these components (such as birds orsquirrels). The presence of such animal life significantly impairs the replacement of fuses of burned-out lightning arrestors by either assaulting the maintenance personnel who carry out such operations, or by creating physical obstructions (such asnests) that must be removed incident to such operations. Additionally, the spliced connection between the lightning arrestor and the cable that supplies electrical power to the light source makes it difficult to replace this component in the event of aburn out of the surge arrestor circuit in the arrestor from a bolt of lightning striking the conductive mast.
A final shortcoming of such prior art systems results from the relatively easy access to the components and cables located inside the masts near the proximal ends thereof. The present access panels are easily opened by vandals who may tamperwith or destroy the components inside, or by thieves who attach the cable leading to the circuit breaker to a truck and pull it out of the ground for the purpose of selling the relatively large amounts of copper in it. In recent years, such vandalismand theft has been a major drain on the maintenance budgets for such lighting system in both the public and the private sectors of the economy.
Clearly, there is a need for an improved outdoor lighting system having some sort of means for preventing the creation of dangerous exposed "hot" wires in the event of a collision between an automobile and a mast, as well as a means forpreventing dangerous destructive forces generated by such collisions from being transmitted from the power cable inside the mast to other splices and connections all throughout the system. Ideally, such a system should deploy the fuse assembly andlightning arrestor in a location which is reasonably accessible to maintenance personnel, but completely inaccessible to potentially hostile wildlife. Such a system should further make is difficult, if not impossible, for vandals or thieves to destroyor steal large lengths of heavy copper cables or other valuable components located inside the masts. Finally, it would be desirable if such a system could be easily retrofitted onto prior art, mast-type outdoor lighting systems in a relatively quick andcost-efficient manner.
SUMMARY OF THE INVENTION
The invention is an improved outdoor lighting system of the type including at least one lighting assembly having a tubular mast, and an electrical cable extending through the mast and underground for connecting a light source located at a distalend of the mast to a circuit breaker that overcomes or ameliorates all of the aforementioned shortcomings associated with prior art outdoor lighting systems. The invention comprises an electrical connector assembly in the electrical cable near theproximal, ground-mounted end of the tubular mast for spontaneously disconnecting the cable at that location upon the application of a tensile force indicative of a vehicle collision with the mast. In the preferred embodiment, the electrical connectorassembly includes first and second matable connectors which spontaneously disconnect upon the application of a tensile force much less than that which would damage the connection between the electrical cable and the underground circuit breaker (or othersource of power) such as, for example, a force of between 20 and 30 pounds. The first and second matable connectors each include means for isolating the conductive pins and barrels contained in each from ambient water to prevent corrosion of the metalforming the conductive pins and barrels.
The improved system preferably further comprises an underground fuse assembly that electrically interconnects the circuit breaker with the underground portion of the cable that extends up from the ground and into the hollow interior of thetubular mast and which terminates in one of the two aforementioned electrical connectors. In the preferred embodiment, the underground fuse assembly includes a junction box connected to the portion of the cable that extends above ground and into thetubular mast, and a male fused connector detachably matable with the junction box. Similar to the aforementioned connector assembly disposed in the bottom of the mast, the fuse assembly connector disconnects upon the application of a tensile force whichis less than the amount of force that would damage other connections within the vicinity of the fuse assembly, i.e., on the order of between 20 and 30 pounds. The fuse assembly and all connections are preferably mounted within an underground box whichhelps to isolate these components from the ambient ground and moisture. Additionally, the lid is secured with fasteners that are removable only with specially made tools to deter would-be vandals an thieves from tampering with or stealing the fuses andcables of the lighting system.
Finally, the improved system may include a lightning arrestor mounted in the same box that contains the fuse assembly. The lightning arrestor includes a surge suppressor circuit which is connected to a ground rod which extends outside thesurrounding box. Preferably, the junction box that forms part of the fuse assembly also functions to electrically connect the cable leading from the light source to the surge suppressor circuit of the lightning arrestor, as well as to the power cable ofan adjacent lighting unit. A third electrical connector may be provided in the cable between the junction box and the surge suppressor circuit so that the surge suppressor circuit may be easily replaced if burned out as a result of lightning strikingthe high source connected to the mast.
The invention further encompasses a method for improving an outdoor lighting system of the aforementioned type wherein a fuse assembly and a lightning arrestor is mounted within the hollow interior of the mast, and connected by way of splices tothe cable inside the mast that connects the light source with the circuit breaker. In this method, the fuse assembly and lightning arrestor are removed from the interior of the mast, and the spliced ends of the cable disposed within the mast arereplaced at least in part with a second cable that terminates in an electrical connector near the distal end of the mast. The fuse assembly and lightning arrestor are relocated in an underground box, and are electrically connected between the circuitbreaker and the cable disposed within the mast by means of a second cable that terminates in a second connector which extends above ground within the interior of the mast, and which is matable with the first connector that ultimately leads to the lightsource.
Both the improved system and the method of the invention results in an outdoor lighting system that is far safer in the event of an automobile collision with one of the masts of the systems, since the forces associated with the collision willonly cause the electrical connector assembly at the proximal end of the mast to spontaneously disconnect without exposing any dangerous wires, and without transmitting any potentially damaging tensile forces to other cables and connectors of the system. Locating the fuse assembly and lightning arrestor in an underground box, instead of within the hollow base of the mast, discourages vandals from stealing or damaging these components while freely allowing maintenance personnel with the proper tools tosafely access these components without disturbing potentially hostile wildlife.
BRIEF DESCRIPTION OF THE SEVERAL FIGURES
FIG. 1 is a cross-sectional side view of a prior art lighting system having a plurality of individual light assemblies that are serially connected to each other and to a common circuit breaker, and whose fuse assemblies and lightning arrestorsare mounted within the mast of the light assemblies;
FIG. 2 is a cross-sectional side view of the improved lighting system of the invention that comprises a plurality of light assemblies which are serially connected to each other and to a common circuit breaker by way of a plurality of utilityboxes, each of which include the fuse assembly and lightning arrestor of one of the lighting assemblies;
FIG. 3 is an enlarged view of one of the utility boxes of the invention, illustrating in detail the electrical connectors used in the fuse assembly and in the lightning arrestor; and
FIG. 4 is an enlarged side view of the proximal end of one of the masts of the light assemblies with the access panel removed, illustrating the electrical connector that is used in lieu of splices to interconnect the cable leading to the lightsource to the fuse assembly contained in the utility box.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference now to FIG. 1, the invention is an improvement of a lighting system 1 of the type comprising a plurality of light assemblies 2 and 2', each of which includes a hollow metallic mast 3. Each mast 3 includes a distal end 5 forsupporting a light source 7 and a proximal end 9 mounted in the ground 11 by means of a concrete reinforced underground base 13. Disposed within the interior of each the masts 3 is an electrical power cable 15 which interconnects the light source 7 ofeach of the light assemblies 2 with a power source. In the case of the first light assembly 2, the power source is an outlet of an above ground circuit breaker 17. In the case of the second assembly 2' (and all subsequent light assemblies not shown)the power source is an outlet of the fuse assembly 19 of the adjacent light assembly. Hence, should the circuit breaker 17 becomes tripped by any of the light assemblies 2,2' for any reason, all of the light assemblies ultimately connected to it will beswitched off.
In the lighting system 1, the electrical power cable 15 of each of the light assemblies includes a first portion 18 that is connected between the light source 7 and the fuse assembly 19 by way of a splice connection 21. The cable 15 furtherincludes a second portion 22 connected between the fuse assembly 19 and a power source in the form of either that circuit breaker 17, or the fuse assembly of an adjacent light assembly. Finally, each of the light assemblies 2 includes a lightningarrestor 23 that is connected by way of a cable 24 to a fuse assembly 19 by way of other splice connections 25. A ground rod 26 forms part of each of the lightning arrestors 23 in order to ground out current surges flowing through the power cable 15 andfuse assembly 19 caused by lightning striking the metallic mast 3. To provide access to both the fuse assembly 19 and lightning arrestor 23 of each of the light assemblies 2,2', includes an access panel 28 at the base of its mast 3.
In the event that an automobile should collide with the mast 3 of any of the light assemblies 2,2', the resulting tensile forces applied to the electrical power cable 15 often caused the cable to break at the splice connection 21 between thefirst portion 18 of the cable 15, and the fuse assembly 19. Depending upon the geometry of the fracture of the mast 3, these exposed "hot" wires could electrify the metallic mast, or the metallic body of the colliding automobile, thereby setting thestage for dangerous electrical shocks to the driver of the automobile, or to rescue workers or onlookers. Even if the exposed wires from the broken splice 21 are short circuited to the extent that the circuit breaker 17 trips, the situation is still notfully satisfactory, as such a tripping would cause the lights on all of the light assemblies 2,2', etc. to turn off, thereby leaving the areas surrounding the accident in total darkness if the accident occurs at night. Finally, because the fuse assembly19 and lightning arrestor 23 are contained within the hollow mast 3 of each of the various light assemblies 2,2', and because some types of hostile wildlife often reside in or build nests within these masts 3, the persons who remove the panels 28 toperform maintenance operations on the light assembly 2 may be stung or bitten by such wildlife.
To solve these and other problems set forth with more specificity in the "Background . . . " section of this application, the improved lighting system 30 illustrated in FIGS. 2-4 was developed. In this improved system, the previously describedelectrical power cable 15 in each of the light assemblies 1,1', etc. is replaced with a different power cable 32. Cable 32 includes a first portion 34 that extends between the light source 7 of each of the light assemblies down to the proximal portion 9of the mast 3 of its respective light assembly 2, as well as a second portion 36 that leads from the proximal end 9 of mast 3 all the way to an underground utility box 38 as shown. As is best seen with respect to FIGS. 2 and 4, an electrical connectorassembly 40 electrically and mechanically interconnects the adjacent ends of the first and second portions 34,36 of the cable 32 in the proximal portion 9 of the mast 3. The electric connector assembly 40 of each of the light assemblies 2,2 ' includes athree-prong male connector at the end of the first portion 34 of the cable 32, and a three-barrelled female connector 44 located at the upper end of the second portion 36 of the cable 32. The female connector 44 extends up through a stub conduit 45 asshown in FIG. 4. Additionally, to relieve tension from the electrical connections between the distal end of the first portion 34 of the cable 32 and the light source 7, the first portion 34 is securely mounted to the inner wall of the mast 3 by means ofmounting clamps 46a,b.
In the preferred embodiment, the electrical connector assembly 40 is a combination of a Model MTP-3 and FTP-3 three pin and three barrel connector manufactured by the Duraline Division of J. B. Nottingham and Company, located in Central Islip,N.Y. Such connectors require an engagement force of 25 pounds in order to mate into position illustrated in FIG. 2, and a disengagement force of 25 pounds in order to detach in the position illustrated in FIG. 4. The bodies of each of the connectors 42and 44 are preferably formed from an elastomer which is integrally molded to the ends of their respective cable portions. The pins of the male connector 42 are mounted on a protruding face that is received in a complementary recess (not shown) in thefemale connector 44 and which serves to crate a water-tight seal between the connectors 42, 44. Alternatively, the water-sealing structure disclosed in the connectors in U.S. Pat. No. 4,911,652, (assigned to the Duraline Division of J. B. Nottinghamand Company) may also be used, the entire text of which is expressly incorporated into the specification of this application by reference.
With reference now to FIGS. 2 and 3, the second portion 36 of the cable 32 includes a first segment 48 that extends between the female connector 45 and the underground utility box 38, and a second segment 50 that extends between the box 38 and asource of electrical power. In the case of light assembly 2, the source of electrical power is circuit breaker 17; in the case of subsequent light assemblies 2', the source of electrical power is an outlet of the utility box 38 associated with anadjacent light assembly 2.
The underground utility box 38 for each of the light assemblies, includes a fuse assembly 52 in the form of a fused male connector 54 which plugs into a junction box 56 as shown. In the preferred embodiment, male connector 54 is a Model 3MFP316-5 adapter-type plug likewise manufactured by the Duraline Division of J. B. Nottingham and Company. Such plugs are capable of holding two 5 amp, 600 volt fuses (not shown) in a tubular recess inside the plug. The fuses may be installed or replacedby simply screwing out the male connector pins that project outwardly from the face of the connector 54. Each of the two current carrying pins includes integrally molded 0 rings for providing a water-tight seal when mated and fully seated to thedistribution block 56. In the preferred embodiment, distrustion block 56 is a Model 3B5-2 block which again is manufactured by the Duraline Division of J. B. Nottingham and Company. Like the previously discussed connector assembly 40, an engagementforce of 25 pounds is required to fully mate or disconnect the fused male connector 54 from the female connector contained with the junction box 56. The junction box 56 is connected to a source of power by means of inlet cable 58 which in turn isspliced to the end of second cable segment 50 of cable portion 36. While not specifically shown in the drawing, junction box 56 is mounted within the walls of the utility box 38 to insulate the splice connection 60 from any tensile forces applied to box56 by male connector 54.
Finally, the underground utility box 39 includes a lightning arrestor 64. The lightning arrestor 64 includes an inlet cable 65 leading from the junction box 56 to a surge arrestor circuit 66. An electrical coupling 69 is provided in the inletcable 65 so that the surge arrestor circuit 66 may be easily replaced in the event that it is burned out as a result of lightning striking the metallic mast 3, which in turn could cause a current surge through cable segment 48 and from thence throughjunction box 56. A ground rod 71 is connected to the surge arrestor circuit 66 by means of an electrical wire 73 clamped thereon. Additionally, the ground rod 71 is attached to the ground wire of the cable segment 50 ' which interconnects the fuseassembly 52 ' of the adjacent light assembly 2 ' with the outlet of the circuit breaker 17 as indicated. The purpose of such a connection is, of course, to assist the lightning arrestor 64 in grounding out any current surge applied to power cable 32 'as a result of lightning striking the mast 3'.
The utility box 38 is located in the ground as shown, and is sealed in a water-tight fashion by means of a lid 73 which prevents any local wildlife from entering or residing in the interior of the box 38. The lid is secured over the top end ofthe box 38 by means of tamper proof hardware 79 of a type known in the prior art which can only be removed with the use of special tools to discourage vandals from tampering with or stealing the components within the box 38.
The method of the invention may be used to convert the lighting system I illustrated in FIG. 1 to the improved lighting system 30 illustrated in FIGS. 2-4. In the first step of this method, both the fuse assembly 19 and lightning arrestor 23 areremoved from the interior of the mast 3 of each of the light assemblies 2,2'. Next, a utility box 38 is provided adjacent to each of the light assemblies 2,2 ' as shown in FIG. 2, wherein the box 38 contains a new fuse assembly 52 and lightning arrestor64 as previously described. Next, the old electrical power cable 15 is replaced with a new cable 32 which has all of the aforementioned portions 34,36 and segments 48,50 interconnected between the connector assembly 40, the utility box 38, and thecircuit breaker 17 or other power source in the manner previously described. It should be noted that the underground segments 48,50 of the portion 36 of cable 32 are completely contained within underground conduits, only portions of which are shown inFIGS. 2 and 4 for the sake of simplicity.
Various modifications and additions to the improved lighting system 30 of the invention will become evident to those skilled in the art. All such modifications and additions are intended to be encompassed within this invention, the scope ofwhich is confined solely by the claims appended below.
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Field of SearchFloor
Pole or post type support
MISCELLANEOUS ATTACHMENTS AND FITTINGS
POSITION OR CONDITION RESPONSIVE SWITCH
And means to block access to power contact surface
Housing comprising resilient latching means
INCLUDING OVERSTRESS PREVENTING MEANS
SEPARATION OR DISCONNECTION AID
Surge prevention (e.g., choke coil)
For electrical power distribution systems and devices
Wire distribution (e.g., harness, rack, etc.)
Distributing and/or combined with overhead
Street, sidewalk, gutter or curb structure
Towers, poles or posts
Ground clamps and cable clips