Abstract:
A power control device prevents unauthorized and unwanted use of electrical devices by locking the plug of the electrical device in the power control device, when the current flowing through the power control device is stopped. The device includes a switch, moveable between on and off conditions by moving a slide lock or bolt, typically by rotating a key in a locking structure. When the slide lock has moved into contact with the switch, such that it is in an off-condition and current is not flowing through the power control device, the slide lock has also locked the plug in the power control device. The electrical device is temporarily inoperable and can not resume normal operation until the power control device is unlocked.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to the field of a power control devices for selectively disabling current flow through the device, and locking a plug in the device when the current flow through the device has been disabled.  
       BACKGROUND OF THE INVENTION  
       [0002]     Users of electrical devices often do not like or do not permit others to use their devices. For example, the device may be set to the user&#39;s personal settings, that if used by another would change the settings. Additionally, in the case of computers, there may be sensitive information, or settings on the computer, that the user does not want anyone to see, and wants the settings kept unchanged. Additionally, users of electrical devices simply do not want others using these devices, as this places additional wear and tear on these devices, limiting the user&#39;s time for enjoying these devices during their usable life.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention is directed to a power control device that prevents unauthorized and unwanted use of electrical devices, typically large electrical devices, such as televisions, computers, and the like, that are difficult to remove from their present locations, due to their size and/or positioning (for example, on shelves, behind desks, in overhead mounts, etc.). The power control device is such that it receives a plug of the electrical device, and allows for the passage of electric current through the power control device, from the current source to the electrical device when the power control device is unlocked. When the power control device is locked, typically by turning a key, electric current flow through the power control device is stopped, and the plug is locked in the power control device. The key is removable when in the locked position. In the locked position, the plug can not be removed from the power control device, without severely damaging or destroying the power control device.  
         [0004]     The present invention also provides an inexpensive, portable, and convenient device that is operable to prevent unauthorized use of electrical appliances and other electrical devices. Such a power control device is useful, for example, with computers, television sets, radios, power tools, and other electrical devices, to interrupt the power to the electrical device and prevent an unauthorized user from plugging the electrical device into an electrical receptacle other than the power control device, thereby circumventing the effectiveness of the electrical device. The power control device of the invention is simple, convenient, inexpensive to manufacture, easy to use, and effective at preventing unauthorized use of an electrical device, to which it attaches, through the plug of the electrical device.  
         [0005]     An embodiment of the invention is directed to a power control device, that prevents unauthorized and unwanted use of electrical devices by locking the plug of the electrical device in the power control device, when the current flowing through the power control device is stopped. The device includes a switch, moveable between on and off conditions, by moving a slide lock or bolt, typically by rotating a key in a locking structure. When the slide lock has moved into contact with the switch, such that it is in an off-condition and current is not flowing through the power control device, the slide lock has also locked the plug in the power control device. The electrical device is temporarily inoperable and can not resume normal operation until the power control device is unlocked.  
         [0006]     Another embodiment of the invention is directed to a power control device. The device has a first contact for electrical communication with a first prong of a plug, the first contact for electrical communication with a current source, and a second contact for electrical communication with a second prong of the plug. There is also a switch in electrical communication with the second contact and for electrical communication with the current source. The switch is movable between an on-condition, where electric current flows through the switch, and an off-condition, where electrical current does not flow through the switch. There is also a moveable member, for example, a slide lock or bolt, moveable (slideable) between a first position and a second position. The moveable member has a first portion for causing the switch to move between the on-condition, when the movable member is in the first position, and the off-condition, when the moveable member is in the second position, and, a second portion for locking the plug in the device when the movable member has moved to the second position.  
         [0007]     Another embodiment of the invention is directed to a power control device. The power control device includes a first contact for electrical communication with a first power prong of a plug, the first contact for electrical communication with a current source, and a second contact for electrical communication with a second power prong of the plug. There is also a switch in electrical communication with the second contact and for electrical communication with the current source. The switch is movable between an on-condition, where electric current flows through the switch, and an off-condition, where electric current does not flow through the switch. There is a key lock assembly and a moveable member in communication with the key lock assembly, for moving the switch between the on-condition and the off-condition, and engaging a plug in the device. The movable member is moved by the key lock assembly, between a first position, where the switch is in an on-condition and the plug is not engaged, and a second position, where the switch is in the off-condition and the plug is engaged.  
         [0008]     Another embodiment of the invention is directed to a power control device. The power control device includes, a first contact, a second contact, and, a switch, electrically coupled to at least one of the first contact or the second contact. The first contact, the second contact, and the switch form a portion of a circuit that couples with a current source. When the power prongs of a plug are in electrical contact with the first contact and the second contact, the first contact, second contact, switch, current source and the electrical device, associated with the power prongs of the plug, define a circuit. There is also a bolt, movable between positions, for activating and deactivating the switch, such that the portion of the circuit configured for coupling with the current source and the electrical device is closed and opened upon movement of the bolt between the positions. The bolt includes a portion for engaging the power prongs of a plug, when the bolt is in a position where the switch is deactivated.  
         [0009]     Another embodiment of the invention is directed to a method for controlling the flow of power to an electrical device. The method includes providing a power control device including, a first contact, a second contact, and a switch, electrically coupled to at least one of the first contact or the second contact. The first contact, the second contact, and the switch form a portion of a circuit that couples with a current source. When the power prongs of a plug are in electrical contact with the first contact and the second contact, the first contact, second contact, switch, current source and the electrical device, associated with the power prongs of the plug, define a circuit. There is also a bolt, movable between positions, for activating and deactivating the switch, such that the portion of the circuit configured for coupling with the current source and the electrical device is closed and opened upon movement of the bolt between the positions. The bolt includes a portion for engaging the power prongs of a plug, when the bolt is in a position where the switch is deactivated. The bolt is in a position where the switch is activated.  
         [0010]     The power control device is then coupled to a current source. A plug, in electrical communication with an electrical device, is attached to the power control device, such that the a first power prong of the plug is in contact with the first electrical contact, and the second power prong of the plug is in contact with the second electrical contact. The bolt is moved to a position where the switch is deactivated. Accordingly, electric current is no longer flowing between the source of electric current and the plug, and the plug is locked in the power control device. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Attention is now directed to the drawing figures, wherein like reference numerals or characters indicate corresponding or like components. In the drawings:  
         [0012]      FIGS. 1A-1C  are perspective views of an embodiment of the invention in a series of exemplary operations;  
         [0013]      FIG. 2A  is a perspective view of the apparatus in accordance with an embodiment of the invention, prior to entry of a plug;  
         [0014]      FIG. 2B  is an exploded view of the apparatus of  FIG. 2A ;  
         [0015]      FIG. 2C  is a top view of the apparatus of  FIG. 2A  with the cover shell removed;  
         [0016]      FIG. 3A  is a perspective view of a slide lock of the apparatus of  FIG. 2A ;  
         [0017]      FIG. 3B  is a front view of the slide lock of  FIG. 3A ;  
         [0018]      FIG. 4A  is a perspective view of the apparatus of  FIG. 2A  with the cover shell removed in operation, and the power prongs of a plug unlocked;  
         [0019]      FIG. 4B  is a top view of the apparatus of  FIG. 4A ;  
         [0020]      FIG. 5A  is a perspective view of the apparatus of  FIG. 2A  with the cover shell removed in operation, and the power prongs of the received plug are locked;  
         [0021]      FIG. 5B  is a top view of the apparatus of  FIG. 5A ; and,  
         [0022]      FIG. 5C  is a detailed view of the locking of the power prongs of the plug of  FIG. 5A . 
     
    
     DETAILED DESCRIPTION  
       [0023]     The present invention provides an apparatus (device) for conveniently controlling the supply of power to an electrical device. The power control device of the present invention minimizes the number of parts, particularly the number of moving parts, so that the power control device is inexpensive to manufacture, reliable, and extremely unlikely to malfunction. The power control device provides a high degree of reliability for enabling or disabling power supplied to an electrical device.  
         [0024]     In addition, the power control device may be provided with an electrical connector or cord having electrical leads connected to a plug that may be plugged into an electrical receptacle (also known throughout this document as an outlet or socket). This allows the power control device to be operable at a distance from the electrical receptacle. Thus, if the electrical receptacle is located behind furniture or in another location that is not readily or conveniently accessible, the power control device may be operable in a more readily accessible location. Alternately, an electrical plug may be mounted or molded into the housing of the power control device.  
         [0025]     The power control device is key-operable for easy and secure usage. A removable key, when inserted into a locking structure and turned or rotated, is operable to lock the plug of the electrical device into the housing of the power control device and to stop power from flowing to the electrical device plug. Therefore, the power control device is easy to use and effectively and securely eliminates unauthorized usage of the electrical device.  
         [0026]     The present invention is shown for use with plugs that are, for example, standard two prong plugs (Type A) (Class II ungrounded plug) and three prong plugs (Type B) (Class I plug, U.S. Standard NEMA 5-15 plug, Canadian Standard CS22.2, n° 42 ), for standard North American (U.S. and Canada) and Central American electrical receptacles (outlets or sockets). Accordingly, in this document, “plugs”, “standard plugs” and “outlets” are standard North American, and Central American plugs and their corresponding outlets (sockets), in which they are received. This is exemplary only, and in no way limiting of the invention, as the invention is easily modifiable and adaptable to all other plugs, as used throughout the world.  
         [0027]      FIGS. 1A-1C  show the apparatus  20  of the invention in an exemplary use, with a electrical device  22 , for example, a large electrical device such as a television, that is difficult to move from its present location, from which a cord  24  extends. The cord  24  terminates in a plug  25 . The plug  25  includes a head  25   a , a head surface  25   b , and power prongs  26   a ,  26   b , with apertures  26   a ′,  26   b ′, and a ground prong  26   c  ( FIG. 2A ). The apparatus  20  includes a body  30 , with an area  32  of openings  34 - 36 , along a first major surface  30   a , for receiving both two and three prong plugs, such as the three prongs  26   a - 26   c  of the plug  25  of the device  22 . The body  30  includes a locking structure  38 , movable by a key  39 . A power cord  40  (with a plug  41 ) typically extends from the body  30 , to an electrical outlet  42 , through which electric current to power the device  22  is obtained. While an apparatus  20  is shown with a cord  40  (as the source of electric current), the apparatus  20  may be a wall mounted unit, directly connected to the outlet  42  or directly wired as the outlet  42 , with the outlet  42  serving as the current source.  
         [0028]      FIG. 1A  shows the apparatus  20  immediately before the plug  25  of the electrical device  22  is connected thereto. Alternately, this figure shows the apparatus  20  immediately after the plug  25  of the electrical device  22  is disconnected therefrom. The key  39  is in a position corresponding to an unlocked locking structure  38 . The apparatus  20  in unlocked, such that it is ready to receive the plug  25  to provide power to the electrical device  22 .  
         [0029]      FIG. 1B  shows the apparatus  20  with the plug  25  of the device  22  connected thereto and received therein. The locking structure  38  is in the unlocked position, whereby electric current is flowing between the outlet  42  and the apparatus  20 , and to the electrical device  22 .  
         [0030]      FIG. 1C  shows the apparatus  20  with the plug  25  of the device  22  connected thereto and received therein. The locking structure  38  is in the locked position, and the key  39  has been moved to a corresponding locked position, whereby electric current flow in the apparatus  20  has ceased, and accordingly, electric current is not flowing between the electrical device  22  and the outlet  42 . The flow of current was broken by an open switch in the apparatus  20 , that was opened upon the locking of the locking structure  38 , when the key  39  moved from the unlocked position to the locked position. The key  39  is typically removable when the locking structure  38  is locked, and may also be removable when the locking structure  38  is unlocked, depending on the configuration of the tumbler and other components of the locking structure  38 .  
         [0031]     Turning to  FIGS. 2A-2C ,  3 A and  3 B, the apparatus  20  is shown in detail. Specifically, in these figures, the apparatus  20  is shown unlocked, to receive a plug or a plug has been removed from the apparatus  20 .  
         [0032]     The apparatus  20  has a body  30 , that is formed of a base shell  50  and a correspondingly configured cover shell  51 . The shells  50 ,  51  are joined in a locking arrangement, and when together, form an interior cavity  54 , for the components of the apparatus  20 . The base shell  50  is designed to carry the components, detailed below, and includes openings  34 ,  35 , extending through the shell  50 , from the major surface  30   a  to the cavity  54 . These openings  34 ,  35  receive the power prongs of a two prong plug. There is also another opening  36  for receiving a ground prong of a three prong plug. A second major surface  30   b  extends along the cover shell  51 . The planes formed by the first major surface  30   a  and the second major surface  30   b  are typically parallel, and define a major plane therebetween.  
         [0033]     Each shell  50 ,  51  includes a divider wall  56 ,  57 , and corresponding portions  58 ,  59 , that when the shells  50 ,  51  are joined together, form a space  60  for receiving and securely confining the locking structure  38 . The shells  50 ,  51  also include corresponding slot portions  62 ,  63  for receiving the ground prong of a plug, and post portions  64 ,  65 , for securely retaining components, i.e., the switch  116 , in a fixed position, when the shells  50 ,  51  are joined together. The base shell  50  includes guide walls  66 . When coupled with aligned guide walls  67 , with apertures  67   a  (corresponding to apertures  26   a ′,  26   b ′ in power prongs  26   a ,  26   b  of a plug  25 , for example, as shown in  FIGS. 1A-1C  and  2 A), and perpendicularly oriented walls  69 , of the cover shell  51 , the guide walls  66 ,  67  of the coupled base  50  and cover  51  shells, serve as guides for the power prongs of the plug upon entry into the apparatus  20 . The perpendicularly oriented wall  69  contacts support walls  66 ,  70 , when the cover shell  51  is joined with the base shell  50 .  
         [0034]     The base shell  50  includes a cut away section  56   a  along its divider wall  56 , and a parallel support wall  70 , with perpendicularly disposed support walls  72 , all of the same height as the cut away section  56   a . This arrangement forms a support on which a slide lock or bolt  110  is movable, by sliding, between first and second positions, as detailed below. In the cover shell  51 , a wall  73 , corresponding to the support wall  70  (in the base shell  50 ), at the same height as the divider wall  57 , couples with the divider wall  56  and support walls  70 ,  72  of the base shell  50 . When the shells  50 ,  51  are combined, these walls  56 ,  57 ,  70 ,  72  and  73  serves to provide a space in which vertical and horizontal movement (sliding) of the slide lock or bolt  110  is confined.  
         [0035]     In the base shell  50 , the space  76  between the cut-away portion  56   a  of the divider wall  56  and support wall  70  defines a groove. Supports  78 , to which the electrical contacts  112 ,  114  attach (as well as electrical wires) are disposed on opposite sides of the ground prong slot portion  62 .  
         [0036]     The base shell  50  and cover shell  51  include corresponding cut-outs  82 ,  83  for accommodating the power cord  40  or the like. The shells  50 ,  51  lock together, when combined, as outwardly tapered tabs  87  are at the ends of fingers  89  in the cover shell  51 , that frictionally engage correspondingly shaped and correspondingly aligned detents  90  in the base shell  50 , along the inner walls  92   a ,  92   b . Additional attachment of the shells  50 ,  51  may be made with adhesives, mechanical fasteners and the like. The base shell  50  and cover shell  51 , when joined, fit securely and have a flush side outer surfaces  94   a ,  94   b ,  95   a ,  95   b . These outer side surfaces  94   a ,  94   b ,  95   a ,  95   b  are typically perpendicular to the major surfaces  30   a ,  30   b.    
         [0037]     The shells  50 ,  51  are typically of a plastic, polymeric or other non-electrically conductive material. The shells  50 ,  51  are typically single pieces with all divider walls  56 ,  57 , slot portions  62 ,  63 , posts  64 ,  65 , walls  67 ,  69 ,  70 ,  72 ,  73 , fingers  89  and detents  90 , integral with the respective shells  50 ,  51 , The shells  50 ,  51  are typically formed by techniques, such as injection molding, blow molding and the like.  
         [0038]     The base shell  50  typically supports the components of the apparatus  20 . These components include a locking structure  38 , a slide lock or bolt  110 , electrical contacts  112 ,  114 , and a switch  116 . The electrical contacts  112 ,  114 , the switch  116 , and the power cord  40  (serving as a current source), that couples with an electrical device through a plug, define a circuit for providing electric current to the electrical device.  
         [0039]     The locking structure  38 , typically includes a cam lock  120 , accessible by the key  39 . The cam lock  120  may be, for example, such that it accommodates a one quarter turn (over an approximately 90 degree arc, typically a 90 degree arc) of the key  39 , from a typically perpendicular orientation with respect to the major plane of the apparatus  20 , to a typically parallel orientation with respect to the major plane of the apparatus  20 . The cam lock  120  includes a movable or rotatable cam  122  at its inner end, that terminates in a stub  124 . The stub  124  is dimensioned to seat between posts  136 ,  137  of the slide lock  110 , such that turning the key  39  rotates the cam  122 , whereby the stub  124  contacts the posts  136 ,  137 , to move the slide lock or bolt  110  between first and second positions, and vice versa, detailed below.  
         [0040]     The slide lock or bolt  110 , as shown in  FIGS. 3A and 3B , is typically, formed of a body  130 , with a head end  132  and a tail end  133 . The posts  136 ,  137  are positioned on one side  130   a  of the body  130 , and extend beyond the body  130 , to bound and confine the stub  124  of the cam  122 . Arms  138 ,  139  extend from the body  130  at the other side  130   b , with pins  142 ,  143  extending from the arms  138 ,  139 . The arms  138 ,  139 , are typically spaced apart from each other at a distance corresponding to the distance of the power prongs of a standard plug.  
         [0041]     The pins  142 ,  143  typically include a cylindrical body  142   a ,  143   a , with a conical head  142   b ,  143   b . The cylindrical body  142   a ,  143   a  is of a diameter slightly less than the diameter of the aperture of a plug, in order to extend through the apertures of the power prongs (for example, apertures  26   a ′,  26   b ′ of power prongs  26   a ,  26   b  of the plug  25 ) when locking the plug in the apparatus  20  is desired, as shown in  FIGS. 5A-5C . Also, as shown in  FIGS. 4A, 4B  and  5 A- 5 C, the pins  142 ,  143  are positioned on the arms  138 ,  139  so as to be aligned with the apertures of the power prongs of a standard plug, when the plug head  25   a , at its surface  25   b  ( FIG. 2A ) abuts the major surface  30   a  on the base shell  50  of the apparatus  20 .  
         [0042]     The slide lock or bolt  110  includes a ridge  144 , protruding from the body  130 , and extending the length of the body  130 . The ridge  144  seats in the space  76  in the base shell  50 , so as to move (slide) in a groove, such that horizontal movement of the slide lock  110  is confined. The side of the body  130   a  is supported by the dividing wall  56 , and travel of the slide lock  110  is limited by the cut away portion  56   a  of the dividing wall  56 . The other side  130   b  of the body  130  and arms  138 ,  139  is supported by the support walls  70 ,  72 , that are the same height as the cut-away portion  56   a  of the divider wall  56 .  
         [0043]     The slide lock or bolt  110  is typically an integral member of a plastic, polymeric or other non-electrically conductive material. It is typically formed as a single piece, by techniques, such as injection molding, blow molding, and the like.  
         [0044]     The electrical contacts  112 ,  114  are typically arranged to include a neutral contact  112  and a positive contact  114 . The contacts  112 ,  114  are typically folded-over pieces of electrically conductive metal, such as copper, alloys thereof, or other electrically conductive materials. The folded-over shape of the contacts  112 ,  114  allows for frictional contacts with the power prongs of the plug, while the power prongs extend beyond the halves  112   a ,  112   b ,  114   a ,  114   b  that form the contacts  112 ,  114 , when the plug is properly received in the apparatus  20 , as shown in  FIGS. 4A, 4B  and  5 A- 5 C and detailed below.  
         [0045]     The switch  116 , is for example, a micro switch, that is moved between closed and open positions, by movement of the slide lock  110 , when the slide lock  110  moves from a first position to a second position, as detailed below. The switch  116  is typically biased in the closed position (shown by the circle  150 ), such that this normally biased closed position is an on-condition for the switch  116  (where current flows through the switch  116 ). A member  152  typically extends from the switch  116 . Contact from the head end  132  of the body  130  of the slide lock  110  (when moved to the second position), moves the member  152 , opening the switch  116 , creating an off-condition. When the head end  132  of the slide lock  110  moves out of contact with the member  152 , or is out of contact with the member  152 , so that the switch  116  is closed (in the on-condition), the slide lock  110  is in a first position. Conversely, when the head end  132  of the slide lock  110  moves into contact with the member  152 , or is in contact with the member  152 , so that the switch  116  is open (in the off-condition), the slide lock  110  is in a second position.  
         [0046]     The switch  116  includes a common terminal  156 , a normally closed terminal  158 , and a normally open terminal  159 , through which electrical connections are made. The switch may be, for example, a micro switch rated at 15 Amps, such as the micro switch commercially available as Part No. VT16001C2 from Highly Electric Company, 782 Heritage Drive, Ft. Lauderdale, Fla. 33326.  
         [0047]     Specifically, the circuit is wired as the power cord  40 , here, for example, the current source, is typically a two wire cord, with a “hot” wire  162 , a neutral wire  163 , and a ground wire  164 . The “hot” wire  162  is electrically connected to the common terminal  156 . The neutral wire  163  is electrically connected to the positive contact  114 , at its end  114   c . The ground wire  164  connects to a lead  168   a  of a ground contact  168  (for contacting the ground prong of a plug) (both the lead  168   a  and ground contact  168   b  of an electrically conductive material), that is in the slot portion  62 . A jumper wire  170  electrically connects the neutral contact  112 , at its end  112   c  to the normally closed terminal  158  of the switch  116 . By connecting at the normally closed terminal  158  of the switch  116 , the normal or default position of the switch  116  is closed (in the on-condition), whereby electric current is flowing between the power cord  40  and the contacts  112 ,  114 . The aforementioned electrical connections are made with conventional connectors  172 . For example, the connectors  172  may be crimp on connectors for 0.187×0.020 contact  14  GA. wire that are preattached to the wire, for example, wires  162 ,  163 ,  164  and  170 .  
         [0048]     Attention is now directed also to  FIGS. 4A, 4B  and  5 A- 5 C to detail the operation of the apparatus  20 . Operation is the same if the apparatus  20  is used with either a two or three prong plug. The difference is that with a three prong plug, the ground prong (for example, ground prong  26   c  of the plug  25  of  FIGS. 1A and 2A ) is received in the opening  36  of the apparatus  20  and the ground prong is confined in the slot portions  62 ,  63  in the shells  50 ,  51 .  
         [0049]     As shown in  FIGS. 4A and 4B , a plug  25  (such as that shown in  FIGS. 1A and 2A ) has been placed into the apparatus  20 . The power prongs  26   a ,  26   b  are received in, and extend through, the openings  34  and  35 , and the ground prong  26   c  is received in, and extends through, the opening  36  in the base shell  50 . The plug head  25   a  abuts the major surface  30   a  of the body  30  of the apparatus  20 . Within the cavity  54 , the apertures  26   a ′,  26   b ′ of the power prongs  26   a ,  26   b  are aligned with the respective pins  142 ,  143 , as well as the apertures  67   a  of the guide walls  67  ( FIGS. 2B and 5C ). Current is flowing to the plug  25  (and the electrical device associated therewith), as the switch  116  is in the closed position (an on-condition), as indicated by the circle  200 . The plug  25  and electrical device (not shown) as attached to the apparatus  20 , result in a closed circuit, formed by the apparatus  20 , the power cord  40  (the current source), and the electrical device (not shown).  
         [0050]     The head end  132  of the slide lock  110  is out of contact with the member  152  on the switch  116 . The key  39  is perpendicular to the major plane of the apparatus  20 . Accordingly, the slide lock  110  is in a first position, where the stub  124  of the cam  122  abuts the outer post  137 , and the slide lock  110  is proximate to the inner wall  92   a  of the shell  50 .  
         [0051]     When disabling the power supply in the apparatus  20 , is desired, the key  39  is, for example, rotated clockwise (in the direction of the arrow  203  in  FIG. 4A ) in the locking structure  38 , for example, by a one quarter or 90 degree turn, to a position parallel to the major plane of the apparatus  20 , as shown in  FIGS. 5A-5C . Rotation of the key  39  has rotated the cam  122  clockwise into contact with the inner post  136 , to slide the slide lock  110 , to a second position, such that its head end  132  is in contact with the member  152 . The contact with the member  152  opens the switch  116  (as indicated in the circle  204 ), such that electric current is no longer flowing through the apparatus  20 . Movement of the slide lock  110  moves the arms  138 ,  139  toward the respective power prongs  26   a ,  26   b , causing the respective pins  142 ,  143 , to move into and through the apertures  26   a ′,  26   b ′ of the power prongs  26   a ,  26   b , with the heads  142   b ,  143   b  of the pins extending into the apertures  67   a  of the guide walls  67 , as shown in  FIG. 5C . The plug  25  is now locked in the apparatus  20 . The key  39  can be removed, and the plug  25 , through the apertures  26   a ′  26   b ′ in the power prongs  26   a ,  26   b , remains locked in the apparatus  20 , with current flow through the apparatus disabled, such that the electrical device, associated with the plug  25  can not be operated.  
         [0052]     Should operation of the electrical device be desired, or resumed, the key  39  is reinserted into the locking structure  38 , and turned (for example, one quarter, or 90 degrees) to the vertical position (with respect to the major plane), such that the apparatus  20  is unlocked, as shown in  FIGS. 4A and 4B . Movement of the key  39 , (for example, a counterclockwise rotation of the key  39  along a 90 degree arc, in the direction of the arrow  205 , as shown in  FIG. 5A ) moves the cam  122  and the stub  124 , that contacts the post  137 , moving the slide lock  110  back to the first position, away from the switch  116 , and toward the inner wall  92   a  of the shell  50 . With the slide lock  110  having been moved out of contact with the member  156 , the switch  116  is closed (moved to an on-condition), where current is again flowing through the apparatus  20 . Additionally, the pins  142 ,  143  have been moved out of and clear of the apertures  26   a ′,  26   b ′ of the power prongs  26   a ,  26   b , as movement of the slide lock  110  moves the arms  138 ,  139  accordingly. The plug  25  may be removed from the apparatus  20  if desired, without damaging it or the apparatus  20 .  
         [0053]     There have been shown and described preferred embodiments of power control devices and methods for their use. It is apparent to those skilled in the art, however, that many changes, variations, modifications, and other uses and applications for the apparatus, its components, and methods for its use are possible, and also such changes, variations, modifications, and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is limited only by the claims which follow.