Abstract:
A water drain for a busway housing at the lowest point in a busway, typically at the elbow transition from vertical to horizontal and at the outside to inside junction of a building. There is a bulge made in the lowermost housing edge with a drain hole. A cap is fitted over the drain hole so no debris/conductors can blow in, but water leaks out.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to busways, and, more particularly, to a busway having an edgewise elbow drain and a drain cap. 
       BACKGROUND 
       [0002]    On “riser” busway applications in which the busbar conductors are vertically oriented, water can eventually get into the busway, trickle down to the bottom-most fitting and collect there, potentially causing a safety hazard because the fittings currently do not have the capability to drain the water effectively. At the same time, it is important to prevent objects (fingers, probes, and the like) and debris from getting into the busway housing, because the busbar conductors carry deadly levels of electrical current. Water and electricity are a bad combination, so it is vital that the exterior of the busway housing be secured against accidental or deliberate attempts to introduce objects into the housing. 
         [0003]    What is needed, therefore, is solution that allows water to drain out of a busway housing while preventing objects or debris from going into the housing. The present disclosure is directed to addressing these and other needs. 
       BRIEF SUMMARY 
       [0004]    This invention addresses the problem of water accumulating in the lower-most elbow of a busway housing to reduce the likelihood of creating a safety hazard while also providing solid ingress protection, such as defined by an IP4X rating. This invention proposes a special form (sometimes referred to as a bubble form) on the lower-most fitting bottom that allows water that falls down into the busway housing to drain away from the busbar conductors housed within the busway. These conductors are typically fully insulated, e.g. encased in a dielectric such as epoxy. The housing bottom also has a drain hole somewhere on the bubble form to drain water that collects in the elbow. A snugly fitting cap seals and covers the drain hole, permitting water to be drained out while at the same time preventing objects or debris from going into the busway housing. 
         [0005]    The foregoing and additional aspects of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided next. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. 
           [0007]      FIG. 1A  is an isometric view of a busway housing incorporating an elbow drainage feature and a drain cap according to an aspect of the present disclosure; 
           [0008]      FIG. 1B  is an isometric view of the bottom of the elbow portion of the busway housing shown in  FIG. 1A  to reveal a drain hole; 
           [0009]      FIG. 1C  is an isometric view of a drain cap that is fitted against the elbow portion shown in  FIG. 1B ; 
           [0010]      FIG. 2  is a functional diagram of an installation of the busway housing of  FIGS. 1A-1C  at the outdoor-to-indoor junction of a building; 
           [0011]      FIG. 3A  is an isometric view of part of the busway housing having the elbow portion; 
           [0012]      FIG. 3B  is a side view of part of the busway housing showing one end of the elbow portion; and 
           [0013]      FIGS. 4A-4E  are various views of scaled mechanical drawings of the drain cap shown in  FIG. 1C . 
       
    
    
       [0014]    While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0015]      FIG. 1A  is a isometric view of a busway housing  100  (side rails removed) incorporating the elbow drainage feature of the present invention. The busway housing  100  houses one or more insulated busbar conductors  102   a - c  (three shown in  FIG. 1 , one for each phase). The busway housing  100  includes a horizontal portion  104  that transitions to a vertical portion  106  at an edgewise elbow portion  108 . The elbow portion has a convex rounded profile to form a channel along the edge  110  of the elbow portion  108 . This convex rounded profile is also referred to as a bubble form, because the cross section of the elbow portion is circular, and the convex orientation of the elbow portion  108  juts outward and away from the horizontal and vertical portions  104 ,  106 . The busbar conductors  120   a - c  follow the profile of the busway housing  100 , and are also horizontal in the horizontal portion  104  and bend orthogonally into a vertical orientation (so-called “risers”) in the vertical portion  106 . 
         [0016]    The horizontal portion  104  of the busway housing  100  includes a first horizontal member  114   a  spaced a distance away from and parallel to a second horizontal member  114   b.  The spacing is sufficient to accommodate the one or more busbar conductors  102   a - c.  The vertical portion  106  includes a first vertical member  116   a  spaced a distance away and parallel to a second vertical member  116   b.  The first horizontal member  114   b  and the first vertical member  116   b  meet at the elbow portion  108 . Preferably, the first horizontal and vertical members  114   a,    116   a  and the elbow portion  108  are integral to one another and formed as a single part, as shown in  FIG. 3A . 
         [0017]    As can be seen from  FIG. 1B , the elbow portion  108  includes a drain hole  112  formed in the channel formed along the edge  110  for draining liquid that collects therein. In this example, the drain hole  112  is formed in approximately the center of the elbow portion  108 , but the drain hole  112  can be positioned at any point other than the center along the elbow portion  108 . The illustrated drain hole  112  has a rectangular shape, but of course the drain hole  112  can have any regular or irregular shape or can comprise more than one hole, like a sieve or a grid. By draining liquids out the drain hole  112 , the elbow portion  108  advantageously reduces the likelihood of a safety hazard caused by liquid otherwise pooling in the bottom elbow portion of the transition between the horizontal and vertical portions of the busway housing in busway housings that lack the elbow portion  108  of the present invention. 
         [0018]    A side view of a mechanical drawing of the elbow portion  108  is shown in  FIG. 3B , with the dimensions shown in inches. The diameter of the convex rounded profile is approximately 0.39 inches in this non-limiting example. Other exemplary dimensions are shown in  FIG. 3B . 
         [0019]    An IP4X rating (also referred to as IP Code) is generally a type of Ingress Protection Rating, and is defined in the IEC (International Electrotechnical Commission) 60529, and classifies degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water in electrical enclosures. Although IP4X is one rating system that can be used herein, other similar ratings can be used, such as corresponding North American enclosure ratings defined by NEMA (National Electrical Manufacturers Association) 250, UL (Underwriters Laboratory) 50 or 508, or CSA (Canadian Standards Association) C22.2 No. 94. The digit 4 in IP4X refers to protection against access by objects greater than 1 millimeter, which is the smallest object dimension specified in the IP rating. 
         [0020]    The exposed drain hole  112  would not pass an IP4X rating, because an object greater than 1 mm could easily penetrate into the interior of the busway housing  100 . An object small enough to penetrate into the exposed drain hole  112  would create a safety hazard as a result of the exposed busbar conductor  102   c,  a hazard that is exacerbated by the presence of water. Accordingly, a drain cap  120  ( FIG. 1C ) is positioned to abut against an exterior surface of the elbow portion  108  adjacent the drain hole  112 . The busway housing  100  alone or in combination with the drain cap  120  is referred to as an edgewise drainage assembly. The drain cap  120  completely covers the drain hole  112  so that any liquids accumulating in the elbow portion  108  drain directly into the drain cap  120 . The drain cap has two walls, a first wall with a concave rounded surface  122  and a second wall with an exterior surface  124  that opposes the concave rounded surface  122 , respectively. A cavity  126  is defined between the concave rounded and exterior surfaces  122 ,  124 . The cavity  126  is open at either end of the drain cap  120  to allow liquids to drain out the ends of the drain cap  120 . The drain cap  120  includes an aperture  128  (see  FIG. 4C ) that is opposite the drain hole and spaced a distance away from the drain hole by the thickness of a sealing edge or lip  130  extending along the ends of the concave rounded surface  122  as shown in  FIGS. 1C and 4E . 
         [0021]    The exterior surface  122  of the drain cap  120  is continuous and has no holes or apertures therein to prevent an IP4X 1 mm straight probe or other object from ingressing into the busway housing  100 . The dimensions of the cavity  126  and the position and shape of the aperture  128  are selected to prevent any object from entering into the drain hole  112  from the ends of the drain cap  120 . The aperture  128  has a crosshatch profile and includes a rounded rectangular portion with two opposing rounded tabs extending from the center of the rounded rectangular portion as shown in  FIG. 4C . This configuration of the aperture  128  allows liquid to drain into the cavity  126  but prevents an IP4X object introduced into the ends of the cavity or debris that is blown into the cavity from penetrating into or accumulating against the drain hole  112 . The aperture  128  can alternately include more than one apertures, resembling a sieve or a grid pattern. 
         [0022]    The aperture  128  is positioned in the center of the concave rounded surface  122 , and the center of the aperture  128  aligns with the center of the drain hole  112  when the drain cap  120  is fitted against the elbow portion  108 . Exemplary dimensions in inches are shown in  FIGS. 4A-4E . All dimensions herein are exemplary only, and those skilled in the art will appreciate that many other dimensions would be suitable for carrying out the invention without departing from the spirit and scope of it. Preferably, the drain cap  120  snaps or clicks into place against the elbow portion  108 . Alternately, the drain cap  120  can be secured against the elbow portion  108  using any conventional means. 
         [0023]    A typical installation  200  incorporating the busway housing  100  and the drain cap  120  of the present invention is shown in  FIG. 2 . A cross-sectional view of the busway housing  100  is shown with the busway housing  100  installed between an indoor and outdoor environment. The sizes of the elbow portion  108  and the drain cap  120  have been exaggerated and are not drawn to scale. Scaled drawings of the elbow portion  108  and the drain cap  120  are shown in  FIGS. 3A-4E . The horizontal portion  104  of the busway housing  100  enters the indoor environment through a wall  202  of a building or structure. A hood  206  is placed over the exposed end of the vertical portion  106 , and conductors  204  are fed out of a hole in the hood  206  for connection to the power utility lines from the utility company. These conductors  204  typically carry one (in the case of one conductor) or three-phase 120VAC or 240VAC current. The drain cap  120  is fitted to abut snugly against the lower-most section of the elbow portion  108  so that any liquids, such as rain or snow, the accumulate in the elbow portion  108  area drain out of the elbow portion  108 , into the drain cap  120 , and out the open ends of the cavity  126  of the drain cap  120 . At the same time, the drain cap  120  prevents an IP4X probe from being introduced into the interior of the busway housing  100 . Thus, the elbowed configuration with the drain cap of the present invention advantageously drains liquids safely away from the busbar conductors  102   a - c  and also prevents objects from entering the interior of the busway housing  100  to the exposed busbar conductors  120   a - c,  which carry deadly levels of electrical current. The horizontal portion  104  is generally level relative to earth or can be installed so that it tilts slightly downward as it exits the wall  202  from indoors to outdoors to prevent any pooled liquids from ingressing into the building. 
         [0024]    In the illustrated examples, liquid drains out of the drain cap  120  through one of the open ends of the cavity  126 . The objectives are a drain cap that allows liquid to drain away from the busway housing  100  while also preventing IP4X objects (greater than 1 mm) from being introduced into the interior of the busway housing  100  through the drain hole  112 . Accordingly, those skilled in the art can appreciate any number of variations of the drain cap will achieve these objectives. The aperture  128  in the drain cap  120  needs to be positioned a sufficient distance away from the opening through which the liquid drains such that a straight object (e.g., a long straight probe having a diameter greater than 1 mm) introduced into the opening cannot penetrate into the drain hole  112  of the busway housing  100 . The opening of the drain cap through which liquid drains also needs to be sized and shaped to prevent any line-of-sight angle for an object to penetrate through both the opening of the drain cap and the drain hole  112 . 
         [0025]    While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations can be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.