Abstract:
A safety system for powering an outdoor light is provided. The system includes a breakaway cable which runs from the luminaire pole to the junction box. The breakaway is connected to a switch which is opened when the breakaway cable is pulled, for example when the luminaire pole is struck. The device may also include a visual indicator at the junction box which indicates whether power is being supplied to the luminaire.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   Not Applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to street and outdoor lighting. More particularly, the invention relates to safety systems for supplying electrical power to luminaire poles used for street lighting. 
   2. Description of Related Art 
   U.S. Pat. No. 5,335,160 to Savoca discloses a luminaire power system that is intended to stop the flow of power to the luminaire pole in the event of the abrupt displacement of the pole. Such a displacement can occur if a motor vehicle strikes the pole. However, Savoca does not provide a visual indicator so that emergency or maintenance personnel who arrive at an accident scene can ascertain whether power is being supplied to the luminaire. Additionally, Savoca uses only a single unplugging action to stop power from reaching the luminaire pole. Another shortcoming of Savoca is that the fuse in Savoca is part of the load cable. Therefore in the Savoca device, power could still be running in the junction box in the event of a short somewhere in the Savoca load cable. 
   Because the Savoca fuse assembly is located in the load cable, one can have the situation in which the luminaire has been displaced (but with no shorting) thereby unplugging the Savoca load cable, yet power will still be throughout the length of the load cable. This power in the load cable can still create a dangerous situation for emergency and maintenance personnel, especially without any visual indicators to indicate the power status in the load cable. 
   The prior art demonstrates a need for a power supply system that does not endanger rescue and maintenance personnel, that provides clear cessation of power if the luminaire pole is displaced from its foundation, and that provides an indicator of whether power is being supplied. 
   SUMMARY OF THE INVENTION 
   A novel luminaire safety system is disclosed. The system includes four key safety elements. The first key safety element is that the fuse assembly is located on the power side of a waterproof enclosure, which is located underground in a junction box. Secondly, the system uses a load cable that runs from the waterproof enclosure to the luminaire pole. This load cable terminates in a splice segment which is detachably connected to the cable in the luminaire pole. The splice segment is selected so that the displacement of the pole will separate the two cables at the splice segment so as not to tear the cables. Thirdly, the system includes a trip mechanism that is located in the waterproof enclosure. 
   The trip mechanism is activated by a separate trip cable that runs from the waterproof enclosure to the base of the luminaire. Even if the load cable and luminaire cable fail to separate from each other at the splice segment, the trip mechanism will ensure that no power is running from the junction box to the luminaire cable. The fourth safety element is that inside the junction box are visual indicators which indicate whether power is running to the load cable. 
   An object of the invention is to provide a luminaire safety system which de-energizes in the event that the luminaire pole is displaced from its foundation. 
   An additional object of the invention is to provide a visual indicator that will show maintenance or emergency personnel the status of the power being supplied to the luminaire pole. 
   An additional object of the invention is to provide a system that includes two methods for de-energizing a luminaire pole. 
   An additional object of the invention is to prevent inadvertent disconnection of the cables that supply power to the luminaire unless the appropriate tensile force is achieved. 
   The present invention has several advantages over the prior art systems. One advantage of the present invention is that it can be easily adapted to existing luminaire pole and junction box configurations. 
   These and other objects, advantages, and features of this invention will be apparent from the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view depicting an embodiment of the luminaire safety system. 
       FIG. 2  is an electrical schematic diagram depicting the junction box and relevant connecting components of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A preferred embodiment of the invention is shown in  FIG. 1 .  FIG. 1  depicts luminaire pole  101  and junction box  104 . Waterproof enclosure  103  is contained within junction box  104 . Power comes into junction box  104  through primary power cable  105 . Fused supply cable  106  has supply cable free end  108 , which is spliced into primary power cable  105 , and supply cable fuse end  109 , which terminates in fused plug  107 . Enclosure power cable  110  is connected at one end to fused plug  107  by a mateable plug. The other end of enclosure power cable  110  goes into waterproof enclosure  103 . 
   Load cable  111  has load cable luminaire end  112  and load cable junction box end  113 . Load cable junction box end  113  goes into waterproof enclosure  103 . As shown in  FIG. 2 , one end of load cable anchor  114  is fixably connected to load cable junction box end  113  while the other end of load cable anchor  114  is fixably attached to junction box  104 . In one preferred embodiment load cable anchor  114  is a Kellem grip attached at one end to load cable junction box end  113  and at other end attached by eye bolt  136  to junction box  104 . In a particularly preferred embodiment one eye bolt can serve as both eye bolt  136  and cable guide  127 . With load cable anchor  114  in place, if a pulling force is exerted on load cable  111 , pulling load cable  111  away from junction box  104 , load cable anchor  114  will serve to prevent load cable  111  from being pulled out of waterproof enclosure  103 . 
   Load cable luminaire end  112  terminates in splice section  115 . Splice section  115  electrically connects load cable  111  to luminaire cable  117 . Load cable  111 , luminaire cable  117 , and splice section  115  are chosen such that the force necessary to separate at splice section  115  is less than the force needed to displace load cable anchor  114 . Luminaire cable  117  continues up into luminaire pole  101  where it is connected to the light (not shown). 
   With reference to  FIG. 2 , the operation and components of waterproof enclosure  103  will now be described. Enclosure power cable  110  comes through cable seal  132  at a sidewall of waterproof enclosure  103  and terminates in three pole switch  118 . Lever  131  (not shown) of three pole switch  118  is connected to switch rod  120  via attenuating spring  133 . Stop pin  121  limits the travel of switch rod  120 . The holes allowing switch rod  120  and load cable junction box end  113  to pass through the sidewall of waterproof enclosure  103  includes sealing means  119  which prevents water from entering waterproof enclosure  103 . 
   In normal operation switch rod  120  will be in the set position (this position may also be referred to as the ready or loaded position) wherein switch rod first end  122  is attached to first end  134  of attenuating spring  133 . Attenuating spring second end  135  is attached to lever  131  (not shown) of three pole switch  118 . Switch rod second end  123  will protrude outside of waterproof enclosure  103 . Breakaway cable first end  125  of breakaway cable  124  is attached to switch rod second end  123 . As shown in  FIG. 1 , breakaway cable second end  126  is fixably attached to luminaire pole  101  by a bolt or some other fastening means. Within junction box  104 , breakaway cable  124  is routed through cable guide  127 . As noted above, in one embodiment, cable guide  127  can also serve as the eye bolt  136 , which attaches load cable anchor  114  to junction box  104 . Cable guide  127  is positioned such that it is roughly in line with the long axis of switch rod  120 . This alignment will ensure a smooth operation of switch rod  120  in the event of the sudden displacement of luminaire pole  101 . In another preferred embodiment, cable guide  127  can be a casement assembly which comprises a cylindrically shaped conduit (not shown) through which breakaway cable  124  is routed. The scope of this invention is intended to include any configurations of cable guide  127  which serve to prevent binding of breakaway cable  124 . 
   In one preferred embodiment, breakaway cable first end  125  is connected to switch rod second end  123  so that these two components will separate after three-pole switch  118  has been tripped into the off position and if breakaway cable  124  continues to pull on switch rod  120 . In a particularly preferred embodiment, breakaway cable first end  125  will separate from switch rod second end  123  with a force of 20 pounds. 
   When luminaire pole  101  is displaced—for example—when it is struck by an out of control automobile—switch rod second end  123  is pulled away from three pole switch  118 , thereby putting three pole switch  118  in the tripped (open) position. As shown in  FIG. 1 , in the tripped position, no power will flow from enclosure power cable  110  to load cable  111 . A maintenance or emergency worker can easily ascertain the status of the power being transmitted to load cable  111  by looking at visual indicators  129  on monitor  116 . When three-pole switch  118  is in the loaded (on) position, visual indicators  129  will be illuminated, indicating that power is flowing into load cable  111 . When three pole switch  118  is in the open (off) position, visual indicators  129  will not be illuminated, indicating that no power is flowing to load cable  111 . 
   The invention provides two separate mechanisms for ensuring that no power is being transmitted to luminaire pole  101  when luminaire pole  101  is displaced from its base. The first mechanism is that breakaway cable  124  will pull on switch rod  120  and send three-pole switch  118  into the tripped position. The second mechanism is that luminaire cable  117  will separate from load cable luminaire end  112  at splice section  115 . This separation occurs because load cable  111  is fixably attached to junction box  104  by load cable anchor  114 . 
   There are of course other alternate embodiments which are obvious from the foregoing descriptions of the invention, which are intended to be included within the scope of the invention, as defined by the following claims.