Abstract:
Signals entering outside plant (OSP) telecommunications enclosures typically do so through weather tight connectors, with one connector mounted to the enclosure and a mating connector connected to a cable bringing the signals to the OSP housing. Such connectors are expensive and require extensive effort to connect the wires of a cable bundle to the connectors. These problems are avoided by allowing cables pre-installed with a cable seal and pre-terminated to cable connectors to pass through an opening in the wall of an OSP housing and seal the cable bundle to the housing to prevent the ingress of environmental elements into the housing through the opening. This permits easier installation and retrofitting of electronic equipment contained within the housing.

Description:
FIELD OF THE INVENTION 
     The invention is directed to the field of electrical connection and more particularly to cable seal apparatus and techniques for outside plant telecommunications housings. 
     DESCRIPTION OF THE PRIOR ART 
     Telecommunications networks often include cables that extend from central installations through one or more cabinets or enclosures to reach the customer. Within these enclosures, a variety of equipment may be mounted to provide the signal processing, splitting or accumulation, and also may provide cross-connections between different cables. The enclosures provide security from accidental or intentional damage to the equipment mounted within and also provide weather protection from environmental damage. Cable entering the enclosure may pass through a cable seal which ensures a weather-tight seal between the cable and the housing. 
     Such enclosures are commonly referred to as outside plant (OSP) housings. 
     Once an OSP housing has been assembled with equipment and has had cable lead into the interior and connected to the equipment, it may be desirable to change the housing to replace the damaged elements. Such damage might be caused by an automobile accidentally impacting the enclosure or a construction accident. 
     For changes made to the housing for any reason, known housings and cable seals require that an end of the cable pass through the cable seal. This necessitates cutting and re-terminating many of the cables or wire pairs contained within a cable bundle that extend into the housing. It is often desirable to use pre-terminated cables to speed installation and reduce the amount of fieldwork required. 
     U.S. Pat. No. 7,132,605 to Homberg et al. discloses a cable seal which is split in such a way as to allow it to be assembled around a cable that is passing into such a housing. 
     PROBLEMS OF THE PRIOR ART 
     A typical OSP housing utilizes weather resistant connector pairs to allow signals from outside the housing to pass into the housing. Such connectors can be expensive, often costing as much as $150 each. Thus, the use of connectors is less desirable from a cost perspective. In addition, substantial labor costs are involved in connecting the wires of an inside cable to the pins of the connector at one end and to connect the wires from the connector to a different connector designed to interface with a connector on, for example, a printed circuit board. Further, wires bringing signals to the OSP housing must be terminated in a mating connector so that the signals can pass through the wall of the OSP housing, using a mating connector. 
     Further, when the contents of the OSP housing need to be reworked, such as to facilitate a change of cables or to facilitate an upgrade to an existing printed circuit board, if a change in connector type must be made, then the entire wiring process needs to be repeated for the new type of connector. 
     Thus, it is highly desirable to have an improved way of connecting outside plant telecommunications equipment to cables providing signals to and from the OSP housing. 
     SUMMARY OF THE INVENTION 
     Accordingly, Applicants have provided improved cable seal apparatus and techniques for interconnecting outside plant telecommunication housings to cables providing signals to and from those housings. 
     One aspect of the invention is directed to an outside plant (OSP) telecommunications housing, which has an opening for allowing a bundle of communications conductors pre-terminated with one or more end connectors to pass through a wall of the housing. A cable seal attaches to said opening to seal said bundle of communications cables to said housing to prevent the ingress of environmental elements into the housing. 
     Another aspect of the invention is directed to a telecommunications system which has a central office for distributing communication signals to subscribers and electronic equipment located between said central office and said subscribers and contained in an outside plant telecommunications housing. The outside plant telecommunications housing has an opening for allowing a bundle of communications conductors pre-terminated with one or more end connectors to pass through a wall of the housing and connect to said electronic equipment. The cable is also pre-installed with a cable seal to attach to said housing to prevent the ingress of environmental elements into the housing through said opening. The connectors may be a customer connector and/or a network connector. 
     Another aspect of the invention relates to a method of installing electronic equipment in an outside plant telecommunications housing, by positioning and securing said electronic equipment in said housing, passing a bundle of communications conductors pre-installed with a cable seal and pre-terminated with one or more end connectors through an opening in a wall of said housing, and by securing said seal to said housing and to said bundle to prevent the ingress of environmental elements into the housing through said opening. 
     Another aspect of the invention relates to a method of retrofitting an outside plant telecommunications housing with different electronic equipment by disconnecting at least one connector from at least one piece of electronic equipment, removing that piece of electronic equipment and replacing it with a different piece of electronic equipment, and removing a cable bundle containing communication conductors terminated in said at least one connector by removing a cable seal securing said bundle to said housing and passing the connector through said housing to remove the cable bundle. A new cable bundle pre-installed with a cable seal and pre-terminated with one or more end connectors is then passed through an opening in a wall of said housing and the cable seal secures the said bundle to the housing to prevent the ingress of environmental elements into the housing through said opening. Then at least one pre-terminated end connector is connected to at least one mating connector on at least one different piece of electronic equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially cut away view of an outside plant enclosure showing the use of mating connectors as used in the prior art. 
         FIG. 2  is a partially cut away view of an outside plant enclosure showing an improvement in cable interconnections in accordance with one aspect of the invention. 
         FIG. 3  shows an example of an outside plant enclosure assembled for installation. 
         FIG. 4  shows an assembled outside plant housing with the top of the smaller piece removed to show simplified sample electronics contained therein in accordance with one aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a partially cut away view of an outside plant enclosure showing the use of mating connectors as used in the prior art.  FIG. 1  shows a housing wall  100  that provides an opening upon which a connector body  110 A is mounted and secured to the housing wall using connector nut  140 . Optionally, seal  130  is provided between the external portions of the connector  110 A and the housing wall to ensure a watertight or water-resistant seal. The connector  110 A has a number of contact pins or receptacles which match a corresponding plurality of pins or receptacles in connector  110 B. Each of the pins or receptacles in connector  110 A and  110 B are individually connected to wires of either wire bundle  120  or internal wire bundle  150 . The connection of wires from a wire bundle to the contact pins or receptacles of connectors can be a time consuming and laborious undertaking. 
     Connectors  110 A and  110 E are mating connectors designed so that the male pin matches a corresponding receptacle pin in the body of the connectors. It does not matter whether connector  110 A or connector  110 B is the male connector. The other connector will be a female connector. Which connector is the male connector will depend upon normal electrical design considerations such as whether or not exposure to high voltage on a pin constitutes a threat of injury to operator personnel or to equipment, should contact with operator personnel or a conductive path on the equipment encounter a relatively high voltage pin. Inside the housing, that is to the left of the housing wall  100  as shown, a wire bundle  150 , generally containing a plurality of wires from the connector  110 A, runs to a cable mounted PCB connector  160 . PCB connector  160  is designed to interface with a board mounted PCB connector  170  of corresponding and mating design which is, in common arrangements, affixed to printed circuit board  180 . 
     As mentioned above, such through the wall sealed connectors  110 A are very expensive. Further, the wiring costs associated with connecting the wires from the connector  110 A to the internal wire bundle  150  and then to the PCB  160  constitute a considerable effort. 
     If, in the course of upgrading the electronics inside the OSP housing, it becomes desirable to replace a PCB  180  with an upgraded and improved version, and if that upgraded and improved version requires a different connector, the cable mounted PCB connector  160  will need to be replaced. That will require disconnecting the wiring to the through the wall connector  110 A so that new wiring can be provided. Similarly, if new wiring is required, the wire bundle  120  might need to be arranged to accommodate changes to the pin assignments of connector  110 B that correspond to the changed pin assignments for connector  110 A. Thus, in addition to the substantial connector costs for such an arrangement, considerable wiring costs are associated with the installation and potential rework of equipment within the OSP housing. 
       FIG. 2  is a partially cut away view of an outside plant enclosure showing an improvement in cable interconnections in accordance with one aspect of the invention. As shown in  FIG. 2 , a cable  220  with a plurality of wires encased, passes through a connector hole  230  through the housing wall  200 . The cable  220  is provided, in the example shown, with two wire pair bundles  240 , each respectively terminated to a connector  250 A and  250 B. Typically, connectors  250 A and  250 B can be cable mounted PC connectors of the type shown in item  160  of  FIG. 1 . The cable  220  is surrounded by a liquid tight strain relief fitting  260  which is preferably of a size known as a PG 29 manufactured or provided by Sealcon, Inc. of Centennial Colo. The size of the connector hole  230  depends upon the particular cable size and the cable fitting selected, and is sufficiently sized to allow connectors  250 A and  250 B to pass through. The cable fitting  260  is selected so that the cable seal  260  can provide a snug and liquid-tight interface to the cable  220 . 
       FIG. 3  shows a modular outside plant enclosure assembled for installation. In the arrangement shown in  FIG. 3  the main casting  300  is already secured to the smaller casting  310 . Each of the main casting and the smaller casting has a removable lid,  320  for the smaller casting and  330  for the main casting respectively. 
       FIG. 4  shows a portion of the housing of  FIG. 3  outside plant housing with lid  320  removed to show simplified sample electronics cable and connectors contained therein in accordance with one aspect of the invention. In this depiction, two cable attached connectors  250 A and  250 E are mounted to corresponding connectors  170  mounted to a panel mounted to the smaller housing  310 . As one can see, the smaller housing is bolted to the larger housing in this view. As shown, the cable with the wire bundles for each of the customer and network connectors shown in  FIG. 4  passes through cable seal  260  and through the wall of the housing into the inside of the smaller housing  310 . 
     As discussed above, the minimum diameter for the connector hole  230  and liquid tight strain relief cable fitting is such as to permit the connectors  250 A and  250 B to pass through the wall of housing  310  even when one wire bundle may already be inserted through the opening. The cable seal body is then connected to the housing and the dome-nut  520 , which forms part of the cable strain relief assembly, secures the cable seal connector to the cable in a liquid-tight arrangement as it is screwed down onto the body of the cable seal. Inside the smaller housing  310 , there is a locking nut  510  which secures the body of the cable seal to the housing optionally using an O-ring or a seal-ring to prevent the ingress of liquid into the housing. Alternatively, threads may be created in housing  310  to replace the locking nut  510 . 
     Replacement of the installed electronic assembly with an upgrade or replacement can be accomplished without cutting or splicing cables. To replace an existing installed electronic assembly in the housing  300  and  310 , the cable attached connectors  250 A and  250 B can be disconnected, the cables can be removed from the housing  310  through the connector hole  230  and be replaced by a different product with connectors having compatible pin assignments for the upgraded version of the product. 
     In this manner, many of the problems associated with the prior art installation and reworking of electronic equipment within OSP (Outside Plant Product) housings can be eliminated. The cost associated with through the wall watertight connectors of the type known in the prior art can be avoided and the through the wall connectors can be replaced with a much less expensive cable seal as described. 
     While various embodiments of the present invention have been illustrated herein in detail, it should be apparent that modifications and adaptations to those embodiments may occur to those skilled in the art without departing from the scope of the present invention as set forth in the following claims. 
     Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.