Abstract:
A circuit breaker lock-out device having a generally U-shaped cross section, configured to mount on a switch having a housing having a recess is provided. Device comprises a first leg connected with a second leg, said second leg having a first aperture configured to receive a blocking member, wherein at least one of said first and second legs has a protrusion configured to engage with said switch housing.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The field of the present invention relates to locking devices generally, and more particularly to a locking device configured to prevent actuation of a switch handle 
   2. Description of the Related Art 
   Typically, electrical distribution circuits include a panel board housing a multitude of switches or circuit breakers, each controlling a separate circuit. It is often necessary to safely “lock-out” or prevent one of the aforementioned circuit breakers from moving to the “ON” position, for example if the respective circuit is being maintained by personnel, while at the same time allowing other circuit breakers in the panel to be freely operable. In other instances, it may alternatively be desirable to lock-out a switching device from moving to the “OFF” position. 
   Typically the lock-out is accomplished by providing a lock-out device for an individual circuit breaker or a distribution panel, that mounts thereon and cooperates with a locking device, such as a padlock, which is located or otherwise disposed to prevent movement or toggling of the desired circuit breaker handle. 
   Circuit breakers may be of single or multiple pole configurations. A conventional single pole circuit breaker of the type commonly known in the art is shown in  FIG. 7 . A circuit breaker  14  includes an insulating housing  16  consisting of hollow molded base  17  and cover  18  that mate along a seam  44  forming circuit breaker top face  47 , side faces  45 ,  46  and rear face  48 . Typically, base  17  and cover  18  are configured with apertures  6 ,  7 ,  8 ,  11  which provide locations for retaining hardware  5  therein, such as for example rivets, to retain base  17  and cover  18  together as a single housing  16 . Disposed within housing  16  are the current carrying elements (not shown) and contact operating mechanism (not shown). The latter is manually operable between “ON” and “OFF” positions by handle  12  extending forward from the top face  47  of housing  16  through an elongated aperture  15 . The top face  47  of housing  16  typically has a raised portion or escutcheon  10  proximate to handle  12  and flat portions  9 ,  3 . In a conventional application, circuit breaker  14  is installed in the field into a distribution panel (not shown), wherein a cover plate (not shown) is disposed on or slightly above flat portions  9 ,  3  with escutcheon  10  and handle  12  protruding through an opening (not shown) in the cover plate (not shown) to allow manual operation of the handle  12 . 
   Many known prior art lock-out devices require costly and complicated multiple piece configurations and additional fastening hardware to install. Additionally, some prior art lock-out devices are difficult to orient such that the lock-out device aperture configured to cooperate with the lock is properly located proximate to the switch operating handle. Still other prior art lock-out devices are not readily field installable. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In view of the foregoing considerations, it is desirable to provide an inexpensive and simple lock out device. It is also desirable to provide a lock-out device that comprises a single piece configuration that cooperates with a locking member and requires no hardware to install. It is also desirable to provide a field-installable lock-out device that is self-orienting with a circuit breaker housing to ensure proper alignment thereon. 
   In one embodiment of the invention, a circuit breaker lock-out device having a generally U-shaped cross section, configured to mount on a switch having a housing having a recess, and an operating handle operable between a first and a second position is provided. The lock-out device comprising a first leg connected with a second leg, said second leg having a first aperture configured to receive a blocking member, wherein at least one of said first and second legs having a protrusion configured to engage with said switch housing. 
   In another embodiment of the invention, method is described for configuring a lock-out device having a generally U-shaped cross section to position a blocking member to prevent operation of a switch, said switch including a housing configured with a recess, and an operating handle operable between a first and a second position. The method includes forming a first leg connected with a second leg; creating in said second leg a first aperture configured to position said blocking member on said switch; and creating on at least one of said first leg and said second leg a protrusion configured to engage said switch housing recess. 
   In another embodiment of the invention, method is described for installing a lock-out device having a generally U-shaped cross section with a protrusion on at least one of the legs, and configured to position a blocking member to prevent operation of a switch, said switch having a housing configured with a recess, and an operating handle operable between a first and a second position, on a switch. The method includes positioning said lock-out device proximate to said switch housing, orienting said lock-out device above said switch housing, applying a force to install the lock-out device on said switch housing, allowing the legs of said generally U-shaped cross section to flex outwardly, and removing said force when said protrusion is received by said switch housing aperture. 
   The above brief summary sets forth rather broadly the more important features of the present invention in order that the detailed description thereof that follows may be better understood, and in order that the present contributions to the art may be better appreciated. In this respect, before explaining several embodiments of the invention in detail, it will be understood that the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood, that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
   As such, those skilled in the art will appreciate that the conception, upon which disclosure is based, may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a presently preferred embodiment of the invention, in which: 
       FIG. 1  illustrates a perspective view of a circuit breaker having lock-out device of an embodiment of the present invention installed thereon; 
       FIG. 2  illustrates a perspective view of the elements of  FIG. 1  with a padlock mounted thereon which blocks the circuit breaker handle to prevent movement thereof from a first position to a second position; 
       FIG. 3  illustrates a perspective view of an embodiment of lock-out device of the present invention; 
       FIG. 3   a  illustrates a magnified detail view of a feature of the lock-out device of  FIG. 3 ; 
       FIG. 4  illustrates an end view of the lock-out device of  FIG. 1  looking in the direction A-A; 
       FIG. 4   a  illustrates a magnified detail view of a feature of the lock-out device of  FIG. 4 ; 
       FIG. 7  illustrates a perspective view of a conventional circuit breaker of the kind known in the art without an embodiment of the present invention installed thereon. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
   Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, one of the embodiments of the current lock-out device of the present invention will now be described. 
     FIGS. 3 and 3   a  illustrate an exemplary lock-out device  25  of an preferred embodiment of the present invention in perspective view. Lock-out device  25  is generally U-shaped in cross-section and preferably formed of a single piece of relatively rigid material such as stainless steel having a thickness of about 0.028 in. (0.711 mm). Lock-out device  25  preferably includes locating surfaces  27 ,  28  forming the bight of the generally U-shaped cross section, and legs  29 ,  30  configured to form an aperture  92 . Leg  29  is provided with a tab or extension  32  with an aperture  33 . Lock-out device  25  is shown with legs  29 ,  30  configured with protrusions  38 ,  39 ,  40 ,  41  disposed thereon and being oriented to be received within with the recesses  6 ,  7 ,  8 ,  11  of a circuit breaker housing  16  ( FIG. 4 ) to retain lock-out device  25  on the circuit breaker  14 . In one embodiment, protrusions  38 ,  39 ,  40 ,  41  are formed integral to lock-out device  25 , for example by a lancing, stamping or staking operation. In an exemplary embodiment, the lanced protrusions  38 ,  39 ,  40 ,  41  each form an angle of between 10 and 15 degrees with respect to their respective legs  29 ,  30  in order to maximize the retention forces of lock-out device  25  on the circuit breaker  14 . The protrusions  38 ,  39 ,  40 ,  41  are each lanced to have a width of about 0.062 in. (1.57 mm), a height of about 0.125 in. (3.18 mm), and have a depth of about 0.025 in. (0.64 mm). 
     FIG. 1  illustrates an exemplary lock-out device  25  of a preferred embodiment of the present invention shown in operative position installed on a circuit breaker  14 . Referring to  FIGS. 1 ,  2 ,  3 ,  3   a , Leg  29  is provided with the extension  32  extending outward from housing  16  proximate to one side of handle  12  and in a plane generally parallel to the plane of movement for handle  12 , and configured with the aperture  33  proximate to circuit breaker operating handle  12 . Aperture  33  is oriented to receive a suitable blocking device such as a shackle  35  of a padlock  36  for example. Locating surfaces  27 ,  28  are disposed on circuit breaker face flat portions  9 ,  3  ( FIG. 7 ) and cooperate with circuit breaker face escutcheon  10  and establish the proper end-to-end position for lock-out device  25  on housing  16 . It will be understood that locating surfaces  27 ,  28  can alternatively cooperate with circuit breaker housing  16  ends  42 ,  43  or other features of the circuit breaker housing  16  without departing from the scope of the invention. 
   Referring to  FIG. 2 , a padlock  36  having a shackle  35  is shown mounted to the lock-out device  25 . The shackle  35  is positioned by aperture  33  on extension  32  so as to block movement of handle  12  of circuit breaker  14  from a first position to a second position, such as for example from an “OFF” position an “ON” position. It will be appreciated that as an alternative to a padlock  36  having a shackle  35 , any of a variety of suitable blocking devices can cooperate with aperture  33  on extension  32  to block movement of handle  12  of circuit breaker  14  from a first position to a second position without departing from the scope of the invention. 
   In the event handle  12  of circuit breaker  14  is in the “ON” position, the aperture  33  on extension  32  is proximate to and aligned with handle  12  such that handle  12  prevents insertion of a blocking device through aperture  33 , thus preventing handle  12  from inadvertently being locked in the “ON” position. 
   If desired, the location of aperture  33  on extension  32  may alternatively be selected to enable a blocking device, such as a padlock  36  having a shackle  35 , to block movement of handle  12  of the circuit breaker  14  to the circuit breaker “OFF” position. It will be understood that the location of the aperture  33  on extension  32  may be determined at the time of manufacture or by modification, such as by drilling for example, in the field. 
   Referring to  FIG. 4 , an end view of the lock-out device of  FIG. 2  is shown looking in the direction A-A. In the magnified detail view of  FIG. 4   a , protrusion  41  is shown received within the aperture  7  and retaining lock-out device  25  on circuit breaker  16 . 
   It will be apparent from the description herein that lock-out device  25  may be easily installed on circuit breaker housing  16  manually and without need of tools. Lock-out device  25  is installed on switch housing  16  by manually orienting the lock-out device  25  above the switch housing  16  such that each leg  29 ,  30  is aligned above the housing  16  side faces  45 ,  46 , with aperture  92  aligned above escutcheon  10  such that the tab  32  is proximate to the switch handle  12 . By applying a downward force to the lock-out device  25  and sliding over the switch housing  16 , the legs  29 ,  30  flex slightly outwardly. The downward force is removed when the protrusions  38 ,  39 ,  40 ,  41  are received by the apertures  6 ,  7 ,  8 ,  11  and the legs  29 , flex back to original orientation. However, once protrusions  38 ,  39 ,  40 ,  41  are received within with the recesses  6 ,  7  of the circuit breaker housing  16 , tools will be required to remove lock-out device  25  from circuit breaker housing  16  resulting in distortion or other damage to the lock-out device  25 . 
   With respect to the above description, it should be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, form function and manner of operation, assembly and use, are deemed readily apparent and illustrated in the drawings and described in the specification are intended to be encompassed only by the scope of appended claims. 
   In addition, while the present invention has been shown in the drawings and fully described above with particularity and detail in connection with what is presently deemed to be practical and several of the preferred embodiments of the invention, it will be apparent to those of ordinary skill in the art that many modifications thereof may be made without departing from the principles and concepts set forth herein. Hence, the proper scope of the present invention should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications and equivalents. 
   This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.