Abstract:
A blocking outlet and corresponding locking plug provide a completely enclosed safety electrical connection system for supplying electrical power from a wall fixture. The blocking outlet installs in a conventional wall-mounted electrical box, providing access to building electrical wiring. The outlet has receptacles that retain spring-loaded covers, which have a closed position generally flush with the front side of the face plate. The springs provide sufficient tension to the covers to block small children from inserting fingers or foreign objects into a receptacle, preventing inadvertent exposure to hazardous voltage. Yet adults can easily insert a corresponding locking plug directly into a receptacle without cover removal. Regardless, the interior of a receptacle has no exposed contacts. Small access apertures in the interior of an outlet receptacle contain recessed contacts. When inserted, the plug compresses the cover fully into the receptacle to an open position, exposing the access apertures to retractable plug prongs. An ergonomic finger hold on the plug is pulled-out to retract the prongs for insertion into an outlet. After insertion, the finger hold is pushed-in to extend the prongs into the access slots, wiping against the outlet contacts and connecting the plug to electrical power. The extended prongs also lock the plug into the receptacle. For removal, the finger hold is pulled-out, unlocking the plug, which can then be easily pulled from the outlet. A face plate seals the receptacles and provides a wall trim for both the electrical box and the outlet in a manner comparable to a standard face plate. An adapter plug has a socket that accepts a standard AC plug, converting it to a locking plug.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/761,290 filed Jan. 16, 2001, now U.S. Pat. No. 6,494,728, incorporated by reference herein, which relates to and claims the benefit of prior U.S. Provisional Patent Application No. 60/176,123 entitled Safety-Lock Outlet Assembly, filed Jan. 14, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     A standard electrical outlet has open slots that expose children to potentially lethal electrical shock hazards. A curious child is prone to insert a conductive object into one of the slots. A child can be shocked if they are in simultaneous contact with a “hot” conductor and a low impedance path to ground. To avoid this risk, parents of young children frequently insert nonconductive plugs into all unused outlets to block out other objects. These plugs, however, significantly reduce outlet convenience. Standard AC plugs also create a shock hazard due to their tendency to pull partially out of an outlet, leaving exposed prongs that remain connected to electrical power. A child can easily touch these with their small fingers or a conductive object. Further, in research, industrial or military environments, an explosion hazard exists when electrical outlets are used in the vicinity of volatile chemicals and gases, which can be ignited with an inadvertent spark at an exposed contact. 
     SUMMARY OF THE INVENTION 
     A safety electrical connection system according to the present invention provides a covered outlet and a corresponding locking plug. Spring-loaded covers block small children from probing the outlet with fingers and foreign objects, yet allow adults to insert a corresponding locking plug without cover removal. Internally, outlet receptacles have no exposed contacts, further reducing the potential for electrical shock. The covered outlet is compatible with existing electrical boxes. A corresponding face plate provides aesthetic wall trim for the outlet and functions to environmentally seal the conductors within. The locking plug is configured to compress the covers when inserted into the outlet. The plug has retracting contacts that extend within the outlet to make a fully-enclosed electrical connection and to lock the plug in place. The plug can be pre-wired as a locking plug or configured as an adapter plug that converts a conventional AC plug to a locking plug. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A-F illustrate top-level features of the safety electrical connection system according to the present invention; 
     FIG. 1A is a perspective view of a covered outlet and a corresponding locking plug; 
     FIG. 1B is a perspective view of a locking plug inserted into a covered outlet; 
     FIG. 1C is a perspective view of two locking plugs inserted into a covered outlet; 
     FIG. 1D is a front view of a locking plug inserted into a covered outlet; 
     FIG. 1E is a sectional side view of a locking plug inserted into a covered outlet; 
     FIG. 1F is a sectional top view of a locking plug inserted into a covered outlet; 
     FIGS. 2A-E illustrate detailed features of a covered outlet; 
     FIGS. 2A-B are front and back perspective views, respectively, of a covered outlet; 
     FIGS. 2C-D are front and back perspective views, respectively, of a covered outlet with the face plate and rear shell removed; 
     FIG. 2E is a back view of a covered outlet with the rear shell removed; 
     FIGS. 3-10 illustrate detailed features of covered outlet components; 
     FIGS. 3A-B are an exploded, back perspective view of a covered outlet assembly; 
     FIGS. 4A-E are top, perspective, front, side and back views of a face plate; 
     FIGS. 5A-E are top, perspective, front, side and back views of an outlet housing; 
     FIGS. 6A-E are top, perspective, front, side and back views of a receptacle cover; 
     FIGS. 7A-D are top, perspective, front and side views of a ground sleeve; 
     FIGS. 8A-D are top, perspective, front and side views of a hot buss; 
     FIG. 8E is a perspective view of a neutral buss; 
     FIGS. 9A-D are top, perspective, front and side views of a bracket; 
     FIGS. 10A-D are top, perspective, front and side views of a rear shell; 
     FIGS. 11A-F illustrate detailed features of a locking plug; 
     FIGS. 11A-B are front and back perspective views, respectively, of a locking plug in a locked position; 
     FIGS. 11C-D are front and back perspective views, respectively, of a locking plug in an unlocked position 
     FIG. 11E is a front perspective view of a locking plug with the door removed, showing an installed standard AC plug; 
     FIG. 11F is a back perspective view of a locking plug with the door removed, showing a standard AC socket without an installed AC plug; 
     FIGS. 12-22 illustrate detailed features of locking plug components; 
     FIG. 12 is an exploded, back perspective view of a locking plug assembly; 
     FIGS. 13A-D are top, perspective, front and side views of a plug housing front-half; 
     FIGS. 14A-D are top, perspective, front and side views of the plug housing back-half; 
     FIGS. 15A-D are top, perspective, front and side views of a finger hold; 
     FIGS. 16A-D are top, perspective, front and side views of a plug door; 
     FIGS. 17A-D are top, perspective, front and side views of a ground bar; 
     FIGS. 18A-D are top, perspective, front and side views of a ground clip; 
     FIGS. 19A-D are top, perspective, front and side views of the neutral prong; 
     FIG. 19E is a perspective view of a hot prong; 
     FIGS. 20A-D are top, perspective, front and side views of a neutral clip; 
     FIGS. 21A-D are top, perspective, front and side views of a hot clip; and 
     FIGS. 22A-D are top, perspective, front and side views of a slide. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Covered Outlet And Locking Plug 
     FIGS. 1A-C illustrate top-level, external features of the safety electrical connection system according to the present invention. As shown in FIG. 1A, the electrical connection system  100  has a covered outlet  300  and a corresponding locking plug  1200 . The outlet  300  is configured to install at a conventional wall location in order to provide a convenient source of electrical power. Power is supplied to conventional electrical loads, such as lighting, appliances and equipment, through the locking plug  1200  and an associated power cord  20  when the plug  1200  is inserted into the outlet  300 . The outlet  300  features covered receptacles  510  that are fitted with spring-loaded covers  600  in order to block access by small children. Electrical contacts are recessed within the covered receptacles  510  to prevent inadvertent contact with electrical conductors if fingers or other objects are inserted into the receptacles  510 . The outlet  300  and locking plug  1200  are keyed to insure the plug  1200  is inserted with the correct orientation and polarization. FIG. 1A illustrates a plug  1200  in an unlocked position with a finger hold  1500  pulled-out. In this position, the plug  1200  can be inserted into or removed from the outlet  300  using the side-mounted finger grips  1410 . 
     FIG. 1B illustrates an interconnected safety electrical connection system  100 . The locking plug  1200  is inserted into a covered wall outlet  300  by pressing the plug  1200  against a cover  600 , which pushes into the associated receptacle  510 . Once the plug  1200  is fully inserted, the finger hold  1500  is pushed in, placing the plug  1200  in the locked position. As the plug  1200  is moved from the unlocked position (FIG. 1A) to the locked position shown, prongs extend from the plug  1200  and into access apertures within the receptacle  510 . The prong contacts wipe against and make electrical contact with respective outlet contacts recessed within these access apertures. Further, as the plug  1200  is inserted into the receptacle  510 , a plug ground bar wipes against and makes electrical contact with an outlet ground sleeve within the receptacle  510 . Also, the extended prongs hold the plug  1200  in the receptacle  510 , advantageously preventing inadvertent removal of the plug  1200 . The extended prongs only make an electrical connection with the outlet contacts when the plug  1200  is fully inserted and completely enclosed within the receptacle  510 , avoiding exposed current-carrying conductors as with conventional AC plugs. 
     As shown in FIG. 1C, two plugs  1200  can be inserted into a duplex covered outlet  300 . The plugs  1200  are rotated 180 degrees relative to each other, maintaining proper plug polarity. The finger holds  1500 , which can unlock and lock a plug  1200  with a push or pull action, along with finger grips  1410  provide an ergonomic way to insert and remove the plugs  1200 . The locking plugs  1200  can be pre-wired as safety plugs or configured as adapter plugs that accept conventional AC plugs of various sizes. 
     FIGS. 1D-F illustrate top-level internal features of the safety electrical connection system  100  according to the present invention. FIG. 1D illustrates a locking plug  1200  inserted into the lower receptacle of a covered outlet  300 . The upper receptacle is unused and closed. FIG. 1E illustrates a side view of a cross-section through the upper and lower receptacles. The lower receptacle shows a plug probe  1310  inserted into the receptacle and the receptacle cover  600  pushed to the receptacle bottom, compressing the cover spring. The plug  1200  is shown in the unlocked position with a pulled-out finger hold. The upper receptacle  510  shows a cover  600  urged by the cover spring to a closed position flush with the face plate. 
     FIG. 1F illustrates a top view of a cross-section through the lower receptacle. As the result of the pulled-out finger hold, the slide  2200  is positioned near the back of the probe and away from the probe face. In this unlocked position, the prongs  1900  are retracted as shown. When the plug is placed in the locked position, the finger hold is pushed in. This positions the slide  2200  near the probe face, forcing the prongs apart and causing the prongs  1900  to extend through the receptacle access apertures  520 , locking the plug  1200  in the receptacle and causing the plug contacts  1282 ,  1284  to connect with the outlet contacts  382 ,  384 . 
     Covered Electrical Outlet 
     FIGS. 2A-E illustrate further detail of the covered outlet  300 . As shown in FIGS. 2A-B, the outlet  300  includes a face plate  400  mounted on the front of, and a rear shell  1000  snapped onto the back of, a receptacle assembly  200  (FIGS.  2 C-D), which is thereby substantially concealed. A mounting screw  340  is inserted through a center hole  440  and into the receptacle assembly  200  (FIGS. 2C-D) to hold the face plate  400  in place. Face plate cutouts  430  provide an entrance to receptacles  510 . The cutouts  430 , covers  600  and the receptacle  510  cross-sections are each keyed so as to prevent the insertion of an improperly oriented locking plug  1200  (FIGS.  11 A-F). 
     FIG. 2A also illustrates an upper receptacle  510  with a cover  600  in an opened position and a lower receptacle  510  with a cover  600  in a closed position. In the closed position, the cover  600  is generally flush with the face plate front side  410 . Closed covers  600  present a relatively featureless surface that is unlikely to attract the attention of small children and that provides an aesthetic, smooth finish to an interior wall. In an open position, a cover  600  is pressed to the bottom of the receptacle  510  to accept a locking plug  1200  (FIGS.  11 A-F). The face plate  400  has a raised wall  450  around each cutout  430  that forms the upper portion of each receptacle  510 . This raised wall  450  facilitates an environmental seal protecting the outlet components. 
     FIG. 2B also illustrates the power wiring connectors  810 ,  910 , which are accessible from and labeled at the rear shell  1000 . Typically, an electrical box is mounted to a wall stud, and the covered outlet  300  is installed in the box and wired to a power cable after wallboard is in place. The outlet  300  is installed in an electrical box (not shown) with mounting plates  920  and associated screws  350  threaded through the plates  920  and into box mounting posts (not shown). The power cable (not shown) is routed through the back of the electrical box. Hot and neutral (common) wires are connected to the outlet  300  at the hot and neutral connectors  810 , as labeled. A ground wire is connected to the outlet  300  at the ground connector  910 , as labeled. An installed outlet  300  is completed by attaching the face plate  400  and associated gasket  310 . 
     FIG. 2C illustrates the front portion of the receptacle assembly  200 . The receptacle assembly  200  has an outlet housing  500  with two receptacles  510 . Inside each receptacle are two access apertures  520  near the bottom of the receptacle  510 . These access apertures  520  are recessed from the surface of the wall in which the outlet  300  is installed. The access apertures  520  are hidden by a spring-loaded cover  600  and revealed only when the cover  600  is moved from a closed position (as shown in the lower receptacle  510 ) to an open position (as shown in the upper receptacle  510 ), such as when a locking plug  1200  (FIGS. 11A-F) is inserted. The access apertures  520  accept prongs that extend from the plug  1200  (FIGS. 11A-F) through the access apertures  520  to electrically connect with outlet hot and neutral contacts. Thus, the outlet contacts are advantageously shielded, only accessible through these small access apertures  520  at the bottom of the receptacle, substantially recessed behind the wall in which the receptacle assembly is installed and hidden by closed covers. Also shown in FIG. 2C, a recessed shelf  518  is located around the periphery of each receptacle  510 . The shelf  518  is configured to accepted a corresponding face plate wall portion  450  (FIG.  2 A), as described above. 
     FIG. 2D illustrates the back portion of the receptacle assembly  200 . The outlet housing  500  has a back face  502  structured to retain the outlet current carrying busses  800  and a bracket  900  that functions as a ground buss. These busses  800  and bracket  900  have connectors that attach the wires of an external power cable. In particular, an external ground wire attaches to the bracket ground connector  910 , external neutral wires attach to the neutral (common) buss connectors  812 , one for each receptacle  510  and external hot wires attach to the hot buss connectors  814 , also one for each receptacle  510 . The busses  800  provide conductivity between the external wire connectors  812 ,  814  and outlet contacts  382 ,  384 . 
     FIG. 2E illustrates the back of the outlet  300 . The outlet neutral  382  and hot  384  contacts are positioned along the receptacle outer wall  516  and adjacent the access apertures  520 . The contacts are advantageously mounted adjacent the front of the apertures  520  as viewed from the face plate front side  410  (FIG.  2 A). In this manner, a foreign object inserted into a receptacle  510  must be pushed through an access aperture  520  and curved back toward the receptacle opening in order to touch the contacts. This provides further protection against inadvertent exposure to current carrying conductors in the outlet  300 . 
     Covered Outlet Components 
     FIGS. 3A-B illustrate the various components of the outlet assembly according to the present invention. The outlet  300  has a face plate  400 , an outlet housing  500 , covers  600 , a ground sleeve  700 , hot and neutral busses  800 , a bracket  900  and a rear shell  1000 . As shown in FIG. 3A, the face plate  400  provides an aesthetic wall trim that covers the remainder of the outlet  300 . The outlet  300  is environmentally sealed by the face plate  400 , which advantageously mates inside the outlet housing  500 , a face plate gasket  310  installed around the face plate periphery and the self-closing covers  600 . The face plate  400  attaches to the outlet housing  500  with a screw  340 , which also secures the ground sleeve  700  to the outlet housing  500 . The face plate  400  is described in further detail with respect to FIGS. 4A-E, below. 
     Also shown in FIG. 3A, the outlet housing  500  defines dual receptacles  510  (outer walls illustrated) that each accept locking plugs  1200  (FIGS. 11A-F) and retain the covers  600 . The outlet housing  500  also retains the ground sleeve  700  and hot and neutral busses  800 . In addition to sealing the receptacles, the covers  600  and associated springs  320  advantageously provide a physical blocking mechanism that discourage child access to the outlet contacts  382 ,  384 . The outlet housing  500  is described in further detail with respect to FIGS. 5A-E, below. The covers  600  are described in further detail with respect to FIGS. 6A-E, below. 
     Further, FIG. 3A illustrates the ground sleeve  700  and current busses  800 . These conductors  700 ,  800  provide an electrical path between an external power source that is wired to the rear of the outlet  300  and an inserted plug  1200  (FIGS.  11 A-F). In particular, the ground sleeve  700  provides ground contacts for plugs  1200  (FIGS. 11A-F) inserted into the receptacles  510  and a ground path to the bracket  900 . The current busses  800  include two neutral busses and two hot busses. The upper busses provide neutral and hot contacts  382 ,  384  to the upper receptacle  510 . Likewise, the lower busses provide neutral and hot contacts  382 ,  384  to the lower receptacle  510 . The busses  800  also provide connectors for external power wires attached to the busses  800  using wire clamps  330  and screws  360 . The ground sleeve  700  is described in further detail with respect to FIGS. 7A-D, below. The busses  800  are described in further detail with respect to FIGS. 8A-E, below. 
     In addition, FIG. 3A shows that the busses  800  are positioned at diagonal corners of the outlet housing  500  and electrically coupled with neutral  392  and hot  394  jumpers. This diagonal positioning of the current busses  800  and the corresponding jumpers  392 ,  394  accommodate the polarization of the plugs  1200  (FIGS.  11 A-F), which are relatively rotated 180° for insertion in opposite outlet receptacles  510 , as shown in FIG.  1 C. The corresponding neutral  382  and hot  384  contacts are located on different sides of each receptacle  510 , accordingly. 
     FIG. 3A also illustrates the bracket  900 , which provides a mount for the outlet  300  to install within a standard electrical box. Further, the ground sleeve  700  connects to the bracket  900 , which provides a ground connector for an external ground wire using a screw  370 . The bracket  900  is attached to an electrical box using screws  350 . The bracket  900  is described in further detail with respect to FIGS. 9A-D, below. 
     As shown in FIG. 3B, the rear shell  1000  mates with the rear portion of the outlet housing  500 , and provides environmental protection to the current carrying busses  800 . External power and ground connectors are exposed through openings  1030 ,  1040 . Descriptive labeling  1070  is provided on the back of the rear shell  1000  as a guide for external wiring. The rear shell  1000  is described in further detail with respect to FIGS. 10A-D, below. 
     Face Plate 
     FIGS. 4A-E illustrate the face plate  400 , which provides a wall trim when attached to the outlet housing front  501  (FIGS.  5 A-E). The face plate  400  has a front side  410 , a back side  420 , two cutouts  430  and a center hole  440 . The face plate  400  is attached with a screw or equivalent securing device threaded through the center hole  440  and into the housing center post  560  (FIGS.  5 A-E). In one embodiment, the face plate  400  is a nonconductive component, meaning that there are no contacts, conductive surfaces or equivalent electrical current carrying portions mounted to, deposited onto or otherwise incorporated on or within the face plate  400 . The covered outlet  300  (FIGS. 2A-E) and corresponding locking plug  1200  (FIGS. 11A-F) are a fully-functional electrical connection system without the face plate  400 . 
     As shown in FIGS. 4A-E, the cutouts  430  are keyed to facilitate orientation of a locking plug  1200  (FIGS. 11A-F) and correspond in size and shape to the outlet receptacles  510  (FIGS.  5 A-E). In one embodiment, the cutouts  430  are keyed with a generally triangular shape. In a particular embodiment, the triangular shape has two rounded corners  412 , a squared apex  414 , a base  416  between the corners  412 , and two sides  418  between the corners  412  and the apex  414 . The apex  414  of each cutout  430  is proximate, and the base  416  of each cutout  430  is distal the center hole  440 . 
     Also shown in FIGS. 4A-E, the face plate  400  has a raised wall  450  extending normal to the back side  420  and around the periphery of the cutouts  430 . With the face plate  400  mounted to the outlet housing  500  (FIGS.  5 A-E), the raised wall  450  mates with a recessed shelf  518  (FIGS. 5A-E) within each receptacle  510  (FIGS.  5 A-E). In this manner, the face plate  400  integrates with each receptacle  510  (FIGS. 5A-E) creating a continuous receptacle inner surface without gaps or openings between the face plate  400  and the outlet housing  500  (FIGS.  5 A-E). Advantageously, the raised wall  450  helps seal the receptacles  510  (FIGS. 5A-E) from environmental conditions such as dust, debris, corrosive elements and hazardous gases and provides for a smooth movement of the covers  600  (FIGS.  6 A-E). The face plate  400  also has a raised portion  460  extending normal to the back side  420  and disposed around the center hole  440 . This supports the mounting screw  340  (FIG. 3A) and retains the ground sleeve  700  (FIGS. 7A-D) within the outlet housing  500  (FIGS.  5 A-E). 
     Outlet Housing 
     FIGS. 5A-E illustrate an outlet housing  500 , which has a generally rectangular cross-section. The outlet housing  500  has a generally planar front face  501  and a structured back face  502 . The outlet housing  500  defines two enclosed receptacles  510 , each with an opening  503  at the front face  501 . In one embodiment, the receptacles are keyed with a generally triangular cross-section with rounded corners and a squared apex corresponding to the face plate cutouts  430  (FIGS.  4 A-E), described above. Inside the receptacles  510  is an inner wall  512  extending to a closed bottom  514 . Outside the receptacles  510  is an outer wall  516  extending to the back face  502 . The inner wall  512  has a shelf  518  near the front face  501  that mates with a face plate raised wall  450  (FIGS.  4 A-E). A cylindrical spring holder  540  extends from the bottom  514  to retain cover springs  320  (FIG. 3A) that urge receptacle covers  600  (FIGS. 6A-E) to a closed position. 
     As shown in FIGS. 5A-E, two access apertures  520  are located along the inner wall  512  and near the bottom  514  of each receptacle  510 . In a particular embodiment, these apertures  520  are recessed 0.594 inches from the front face  501 . Thus, including the face plate thickness, the apertures  520  are recessed at least about 0.6 inches from the face plate cutouts  430  (FIGS.  4 A-E). Locking plug prongs  1900  (FIGS. 9A-E) extend through these apertures  520  to contact outlet contacts  382 ,  384  (FIG. 3A) that rest against contact structure  552  along the outer wall  516  adjacent the access apertures  520 . The outlet contacts  382 ,  384  (FIG. 3A) are mounted on hot and neutral busses  800  (FIGS. 8A-E) inserted along the back face  502 . In particular, the housing  500  retains the busses  800  (FIGS. 8A-E) by inserts  840  (FIGS. 8A-E) that are pressed into insert structure  554  and buss clips  850  (FIGS. 8A-E) that are pressed over clip structure  556 . 
     FIGS. 5A-E further show that two channels  530  are also located along each receptacle inner wall  512  extending from the bottom  514  to an end  532  near the shelf  518 . The channels  530  accommodate cover catches  640  (FIGS. 6A-E) that stop at the ends  532  to retain spring-loaded covers  600  (FIGS. 6A-E) within the receptacles  510 . 
     Also shown in FIGS. 5A-E is a center post  560  having a post hole  562  for attaching a face plate  400  (FIGS. 4A-E) and securing a ground sleeve  700  (FIGS.  7 A-D). Adjacent the center post  560  are slots  564  for inserting the ground sleeve  700  (FIGS.  7 A-D). Grooves  570  are located along the housing top  504  and bottom  505  and bracket structure  580  is located on the back face  502  adjacent the center post  560  to secure a bracket  900  (FIGS.  9 A-D). 
     Receptacle Cover 
     FIGS. 6A-E illustrate a receptacle cover  600 , which has a front face  610 , an open bottom face  620  and walls  630  extending along the periphery of the front face  610 . The cover  600  is keyed in a manner consistent with the face plate cutouts  430  (FIGS. 4A-E) and the cross-section of the receptacles  510  (FIGS.  5 A-E). In a particular embodiment, the cover cross-section is generally triangular shaped with round corners  612  and a squared apex  614 , as described with respect to the face plate cutouts  430  (FIGS.  4 A-E), above. The cover  600  has two flexible catches  640 , one on each side between the corners  612  and the apex  614 , each with a surface  642  parallel to the front face  610 . A cylindrical spring holder  650  extends in a normal direction from the bottom face  620 . A cover  600  is loaded into a receptacle  510  (FIGS. 5A-E) by placing a spring in the spring holder  650 , inserting the spring and the cover  600  into the receptacle  510  (FIGS.  5 A-E), bottom face  620  first, compressing the catches  640  toward the cover and pressing the cover  600  into the receptacle  510  (FIGS. 5A-E) so that the catches  640  snap into the channels  530  (FIGS.  5 A-E). The covers  600  are slidably retained within the receptacles  510  (FIGS.  5 A-E). When pressed into a receptacle  510  (FIGS.  5 A-E), the travel of the cover  600  is limited by extensions  650  hitting the receptacle bottom  514  (FIGS.  5 A-E). When released, the travel of the cover  600  is limited by the catches  640  contacting the channels ends  532  (FIGS.  5 A-E). 
     Ground Sleeve 
     FIGS. 7A-D illustrate the ground sleeve  700 , which has top and bottom ground contacts  710 , a center section  720  joining the contacts  710  at one end, stakes  730  at the other end of the contacts  710 , opposite the center section  720  and a mounting hole  740  through the center section  720 . The ground sleeve  700  fits through slots  564  (FIGS. 5A-E) in the housing front face  501  (FIG. 5C) so that the center section  720  aligns with a center post  560  (FIGS. 5A-E) and the mounting hole  740  aligns with a post hole  562  (FIG.  5 B). The top and bottom contacts  710  line the receptacles  510  (FIGS. 5A-E) along each apex so that the contacts  710  will connect with a plug ground bar  1700  (FIGS.  17 A-D). The stakes  730  are swaged into bracket slots  940  (FIGS.  9 A-D), electrically connecting the bracket external ground connector  910  (FIGS. 9A-D) and the ground sleeve contacts  710 . The ground sleeve  700  is held in place by the face plate mounting screw  340 , which is threaded through the face plate center hole  440  (FIGS.  4 A-D), the ground sleeve mounting hole  740  and the housing post hole  562  (FIG.  5 B). 
     Hot and Neutral Buss 
     FIGS. 8A-E illustrate contact busses  800 . FIGS. 8A-D illustrate a hot buss  801 . FIG. 8E illustrates a neutral buss  802 , which is a mirror image of the hot buss  801 , as illustrated. Four contact busses  800  are used as hot and neutral conductors between external power wiring and the outlet contacts  382 ,  384  (FIG.  3 A). A contact buss  800  has a connector  810 , a contact holder  820 , a crimp  830 , an insert  840  and a “U”-shaped clip  850 . The outlet contact  380  is a conductor such as silver and is attached to the contact holder  820  using a swage process. An external hot or neutral power wire is connected to the connector  810  using a screw  360  (FIG. 3A) threaded through a clamp  330  (FIG.  3 A). An outlet  300  (FIGS. 2A-E) can be wired fill-hot or half-hot. For example, half-hot wiring allows one receptacle to be controlled by a wall switch. For full-hot wiring, neutral and hot jumpers  392 ,  394  (FIG. 3A) are installed between individual busses  800 . Each end of a jumper  392 ,  394  (FIG. 3A) is connected to a crimp  830 , such as with a resistance weld. A contact buss  800  is installed in the housing back face  502  (FIGS. 5A-E) by pressing the insert  840  into and the clip  850  over corresponding housing structure. 
     Bracket 
     FIGS. 9A-D illustrate the bracket  900 . The bracket  900  is generally “U”-shaped and functions to secure the outlet  300  within a standard electrical box and provides a ground buss. The bracket  900  has a ground connector  910 , upper and lower mounting plates  920 , mounting holes  922  centered within the plates  920 , upper and lower clips  930 , stake slots  940  and crimps  960 . A mounting plate  920  is located at each end of the bracket  900 . The outlet  300  (FIGS. 2A-E) is mounted to an electrical box with mounting screws  350  (FIG. 3A) threaded through the mounting holes  922  and into box posts (not shown). The bracket.  900  attaches to the housing back face  502  (FIGS. 5A-E) with clips  930  around the outside of the receptacle structure. Crimps  960  insert into and fold over to retain the rear shell  1000 . Ground sleeve stakes  730  (FIGS. 7A-D) are swaged into the slots  940  to electrically connect the ground sleeve  700  (FIGS. 7A-D) to the bracket  900 . An external ground wire is attached to the bracket connector  910  with a ground screw  370 . 
     Rear shell 
     FIGS. 10A-D illustrate the rear shell  1000 , which has a back face  1010  and an open front face  1020 . The front face  1020  fits over the outlet housing  500  (FIGS.  5 A-E). Bracket crimps  960  (FIGS. 9A-D) fit through slots  1050  and are folded onto the back face  1010  to secure the rear shell  1000  to the housing  500  (FIGS.  5 A-E). Side openings  1030  provide access to buss connectors  810  (FIGS.  8 A-E). A back opening  1040  provides access to the ground connector  910  (FIGS.  9 A-D). 
     Locking Plug 
     FIGS. 11A-F illustrate further detail of the locking adapter plug  1200 . FIGS. 11A-B illustrate the plug  1200  in the locked position. FIGS. 11C-D illustrate the plug  1200  in the unlocked position. FIGS. 11E-F illustrate the plug  1200  with the door  1600  removed. As shown in FIGS. 11A-B, the plug  1200  has a probe  1310  and a case  1110 . The case  1110  is divided into upper  1120  and lower  1130  compartments. The probe  1310  extends perpendicularly from the upper compartment  1120  and has a keyed shape corresponding to the outlet receptacle  510  (FIGS.  2 A-E). The upper compartment  1130  has finger grips  1410  that facilitate plug removal and insertion. The upper compartment  1120  also has a cutout  1420  that accepts the finger hold  1500 . The lower compartment  1130  houses a standard AC plug  10 , which inserts into a corresponding standard AC socket  1150  (FIGS.  11 E-F). In this manner, a standard AC plug  10  is adapted to a locking plug  1200 . 
     Also shown in FIGS. 11A-B, the plug  1200  has a locked position with the finger hold  1500  pushed into the upper plug compartment  1120  and prongs  1900  extended from, and generally perpendicular to, the probe  1310 , one from each corner. In this locked position, with the probe  1310  inserted into an outlet receptacle  510  (FIGS.  2 A-E), the prongs  1900  each extend into an access aperture  520  (FIGS.  2 A-E), which locks the plug  1200  into the outlet  300  (FIGS.  2 A-E). One prong  1900  has a neutral contact  1282  configured to electrically connect to a neutral outlet contact  382  (FIG.  3 A). Another prong  1900  has a hot contact  1284  configured to electrically connect to a hot outlet contact  384  (FIG.  3 A). A ground bar  1700  extends along the apex of the probe  1310  and is configured to electrically connect to an outlet ground sleeve  700  (FIGS.  7 A-D). 
     As shown in FIGS. 11C-D, the plug  1200  has an unlocked position with the finger hold  1500  pulled out of the upper plug compartment  1120  and the prongs  1900  retracted into the probe  1310 . In this position, the plug  1200  can be inserted or removed from an outlet  300  (FIGS.  2 A-E). A gasket  1210  fits around the perimeter of the probe  1310  and against the front face of the case  1110 . When the plug  1200  is inserted into an outlet  300  (FIGS.  2 A-E), the gasket  1210  provides a gas-tight seal for the outlet contact  382 ,  384  and plug contacts  1282 ,  1284 , reducing the explosion hazard from sparks in the presence of volatile gases and fumes. 
     Also shown in FIGS. 11C-D, a door  1600  covers the standard AC plug  10  contained in the lower compartment  1130 . The door  1600  is retained on the case  1110  by a screw  1270  threaded through one of several adjustment holes  1610  and into a door retention hole  1308  (FIGS.  13 A-D). This allows the door  1600  to accommodate various plug sizes. 
     As shown in FIGS. 11E-F, the door  1600  (FIGS. 11C-D) is removable for access to an AC plug  10 . Guides  1160  on either side of the case  1110  allow the door  1600  (FIGS. 11C-D) to slide over the lower compartment  1130 . An AC plug  10  can be inserted into and removed from a standard AC socket  1150  incorporated within the lower compartment  1130 . Contact clips  1800  (FIGS.  18 A-D),  2000  (FIGS.  20 A-D),  2100  (FIGS. 21A-D) within the socket  1150  provide an electrical connection with the ground bar  1700  and prongs  1900 . 
     Locking Plug Components 
     FIG. 12 illustrates the various components of a locking plug  1200  configured as an adapter for a conventional AC plug. The locking plug  1200  has plug housing front  1300 , a plug housing back  1400 , a finger hold  1500 , a door  1600 , a ground bar  1700 , a ground clip  1800 , prongs  1900 , a neutral clip  2000 , a hot clip  2100 , and a slide  2200 . The housing front half  1300  and back half  1400  provide a housing  1110  for the plug contacts and conductors, a probe  1310  for insertion into the corresponding outlet  300  (FIGS. 2A-E) and an adapter socket  1150  (FIG. 11F) for a standard AC plug. The housing halves  1300 ,  1400  are held together with top screws  1250  inserted from the front half  1300  and a bottom screw  1260  inserted from the back half  1400 . A gasket  1210  fitted around the probe  1310  provides a seal between a covered outlet  300  (FIGS. 2A-E) and the locking plug  1200  when inserted. The housing halves  1300 ,  1400  are described in more detail with respect to FIGS. 13A-D and FIGS. 14A-D below. 
     As shown in FIG. 12, the finger hold  1500  has a stem  1570  that is inserted through the housing back half  1400  and into a slide post  2270 . The slide  2200  is moveable within the probe  1310  so as to actuate the prongs  1900 . Specifically, when the finger hold  1500  is pulled out from the housing  1110 , the slide  2200  allows the prongs  1900  to retract. When the finger hold  1500  is pushed into the housing  1110 , the slide  2200  forces the prongs  1900  outward, causing them to extend from the probe  1310 . The finger hold  1500  is described in further detail with respect to FIGS. 15A-D, below. The slide  2200  is described in further detail with respect to FIGS. 22A-D, below. 
     Also shown in FIG. 12, the door  1600  slides onto the housing  1110  to enclose, retain and provide strain relief for a standard AC plug inserted into the adapter socket  1150  (FIG.  11 F). The door  600  is held in place with a retaining screw  1270  threaded through one of several adjustment holes, allowing the door to accommodate various sized standard AC plugs. The door  1600  is described in further detail with respect to FIGS. 16A-D, below. 
     Further, FIG. 12 illustrates the ground path from an outlet  300  (FIGS. 2A-E) to a standard AC plug. A ground bar  1700  is located on the probe  1310  and contacts an outlet ground sleeve when the locking plug  1200  is inserted into a covered outlet  300  (FIGS.  2 A-E). A ground jumper  1220  electrically connects the ground bar  1700  to a ground clip  1800 . A standard AC plug ground pin connects with the ground clip  1800  when inserted into the adapter socket  1150  (FIG.  11 F). The ground bar  1700  is described in further detail with respect to FIGS. 17A-D, below. The ground clip  1800  is described in further detail with respect to FIGS. 18A-D, below. 
     In addition, FIG. 12 illustrates the current carrying paths from an outlet  300  (FIGS. 2A-E) to a standard AC plug. The prongs  1900  have neutral  1282  and hot  1284  contacts. When the plug  1200  is inserted in an outlet  300  (FIGS. 2A-E) and placed in the locked position, the prongs  1900  extend so that the neutral  1282  and hot  1284  plug contacts separately connect with neutral and hot outlet contacts. A neutral jumper  1232  electrically connects the neutral contact  1282  to a neutral clip  2000 . A hot jumper  1234  electrically connects the hot contact  1284  to a hot clip  2100 . Standard AC plug hot and neutral blades separately connect with the neutral  2000  and hot  2100  clips when inserted into the adapter socket  1150  (FIG.  11 F). The prongs  1900  are described in further detail with respect to FIGS. 19A-E, below. The neutral clip  2000  is described in further detail with respect to FIGS. 20A-D, below. The hot clip  2100  is described in further detail with respect to FIGS. 21A-D, below. 
     Plug Housing 
     FIGS. 13A-D and  14 A-D illustrate the front half  1300  and back half  1400  of the plug housing  1110  (FIGS.  11 A-F), respectively. FIGS. 13A-D show the housing front half  1300  has a probe  1310  and a case half  1320 . The case half  1320  has a generally planar front face  1301 , an open and structured back face  1302 , an upper portion  1322  and a lower portion  1324 . 
     As shown in FIGS. 13A-D, at the upper portion  1322 , the probe  1310  extends normally from the housing front face  1301  to a planar front face  1311 . In a particular embodiment, the access openings  520  (FIGS. 5A-E) are recessed at least about 0.6 inches from the face plate cutouts  430  (FIGS.  4 A-E), as described with respect to FIGS. 5A-E, above. In a corresponding embodiment, the probe extends at least about 0.6 inches from the housing front face  1301  to the probe front face  1311 . The probe  1310  is generally hollow, and has an open back face  1318  proximate the housing back face  1302  to accept the prongs  1900  (FIGS. 19A-E) and slide  2200  (FIGS.  22 A-D). The front face  1311  is keyed and, in one embodiment, is generally triangular in shape with an apex, base and corners corresponding to the shape of the face plate cutouts  430  (FIGS. 4A-E) and the outlet receptacles  510  (FIGS.  5 A-E), as described with respect to FIGS. 4A-E, above. The probe  1310  has a groove  1312  running its length along the apex and a slot  1313  near the probe face  1311 . The slot  1313  accepts a ground bar insert  1720  (FIGS. 17A-D) to retain the ground bar  1700  (FIGS. 17A-D) within the groove  1312 . Elongated openings  1315  at the probe face  1311  near its base provide for the extension and retraction of prongs  1900  from the probe  1310 . 
     Also shown in FIGS. 13A-D, at the lower portion  1324  along the front face  1301  is a guide half  1342 , a door catch  1344  and an indent  1348 . Along the back face  1302  is a post  1306  and socket structure  1360 . The guide half  1342 , in conjunction with a corresponding guide half on the housing back half  1400  (FIGS. 14A-D) slidably retains a plug door  1600  (FIGS.  16 A-D), described below. The door catch  1344  releasably engages one of several door latches  1620  (FIGS. 16A-D) for adjusting to various AC plug sizes. The indent  1348  allows a tool to remove the catch  1344  from a latch  1620  (FIGS.  16 A-D). A retention hole  1308  accepts a screw to secure the door  1600  (FIGS.  16 A-D). Socket structure  1360  retains the ground clip  1800  (FIGS.  18 A-D), neutral clip  2000  (FIGS. 20A-D) and hot clip  2100  (FIGS.  21 A-D). The post  1306  along with screw holes  1304  accept screws to secure together the housing halves  1300 ,  1400  (FIGS.  14 A-D). 
     FIGS. 14A-D show the housing back half  1400  has an open and structured front face  1401 , a generally planar back face  1402 , an upper portion  1408  and a lower portion  1409 . The upper portion  1408  has finger grips  1410  along each side, a post hole  1405 , a cutout  1420  and mounting posts  1404 . The finger grips  1410  facilitate insertion and removal of the plug  1200  (FIGS.  11 A-E). The post hole  1405  accommodates, and slidably retains, the slide post  2270  (FIGS. 22A-D) inserted from the front face  1401  and the finger hold stem  1570  (FIGS. 15A-D) inserted from the back face  1402  into the slide post  2270  (FIGS.  22 A-D). The cutout  1420  accommodates the finger hold cup  1510  (FIGS. 15A-D) when the finger hold  1500  (FIGS. 15A-D) is pushed-in and the plug  1200  (FIGS. 11A-E) is in the locked position. The mounting posts  1404  mate with the screw holes  1304 , which accept screws to secure together the housing halves  1300  (FIGS.  13 A-D),  1400 . 
     Also shown in FIGS. 14A-D, the lower portion  1409  has a socket face  1432 , clip structure  1434  and a screw hole  1406 . The socket face  1432  forms most of the socket  1150  (FIGS. 11A-E) for insertion of a standard AC plug. The clip structure  1434  retains the ground clip  1800  (FIGS.  18 A-D), neutral clip  2000  (FIGS. 20A-D) and hot clip  2100  (FIGS.  21 A-D). A guide half  1442  (FIG.  12 ), in conjunction with a corresponding front half guide  1342  (FIGS.  13 A-D), slidably retains a plug door  1600  (FIGS.  16 A-D), described below. The screw hole  1406  mates with the post  1306  and accepts a screw to secure together the housing halves  1300  (FIGS.  13 A-D),  1400 . 
     Finger Hold 
     FIGS. 15A-D illustrate the finger hold  1500 , which has a cup  1510 , a collar  1540  and a stem  1570 . The cup  1510  has a generally rounded bottom  1512  and back  1514  and generally flat sides  1516  and front  1518  defining a cavity  1520 . The cup back  1514  has a round collar  1540  formed thereon. The cup front  1518  has a crescent-shaped lip  1519 . The cavity  1520  provides a place to insert a fingertip in order to pull-out or push-in the finger hold  1500 , unlocking or locking the plug  1200 . The crescent-shaped lip  1519  allows fingertip access to the cavity  1520  when two plugs  1200  are inserted, as shown in FIG. 1C, above. 
     Also shown in FIGS. 15A-D, a cross-shaped, cross-section stem  1570  has a slightly flared base  1572  proximate the collar  1540  and a slightly flared and slotted tip  1574  distal the collar  1540 . The stem  1570  extends, and is slightly tapered, from base  1572  to the tip  1574  in a direction generally normal to the front  1519 . The tapered, cross-sectioned stem  1570 , slotted and flared tip  1574  and flared base  1572  facilitate insertion and retention of the stem  1570  into a slide post  2270  (FIGS.  22 A-D). The collar  1540  provides a stop and mating portion to the post end  2272  (FIGS.  22 A-D). Attached to the slide post  2270  (FIGS.  22 A-D), movement of the finger hold  1500  actuates the slide  2200  (FIGS. 22A-D) and extends or retracts the prongs  1900  (FIG.  19 A-E), locking and unlocking the plug  1200  (FIGS.  11 A-F), accordingly. 
     Plug Door 
     FIGS. 16A-D illustrate a plug door  1600 , which is generally box-shaped with an open top  1602  and closed bottom  1604 , an open first side  1601  and a second side  1603  having a cord slot  1640 , and a front face  1606  and back face  1608 . The door covers and retains a standard AC plug inserted in an adapter socket  1150  (FIGS.  11 A-F). The top  1602  has rails  1630  that fit over and slide along housing guides  1160  (FIGS.  11 A-F). The front face  1606  has adjustment holes  1610  and latches  1620  that allow the door  1600  to accommodate different-sized standard AC plugs. The latches  1620  position the door on a catch  1344  (FIGS. 13A-D) and a screw threaded into an adjustment hole  1610  aligned with a retention hole  1308  (FIGS. 13A-D) secures the door  1600 . The cord slot  1640  accommodates a standard AC power cord and functions as a strain relief. 
     Ground Bar 
     FIGS. 17A-D illustrate the ground bar  1700 , which has an elongated, curved spring contact  1710 , an insert  1720  at one end of the contact  1720 , stops  1730  at the other end of the contact  1720  and a jumper pad  1740 . The contact  1710  is shaped to fit along a groove  1312  (FIGS. 13A-D) at the probe apex. The ground bar  1700  is retained along the apex by the insert  1720  fitted into a groove slot  1313  (FIGS. 13A-D) at the probe face  1311  (FIGS. 13A-D) and the housing back  1400  (FIGS. 14A-D) fastened against the stops  1730  at the probe back face  1318  (FIGS.  13 A-D). A wire end of a ground jumper  1220  (FIG. 12) is resistance welded to the pad  1740 . The spring contact wipes along and maintains pressure against the outlet ground sleeve  1700  (FIGS. 17A-D) when the plug  120 D (FIGS. 11A-F) is inserted in an outlet receptacle  510  (FIGS.  2 A-E). A ground path is then established from the ground sleeve  700  (FIGS.  7 A-D), through the ground bar  1700  and jumper  1220  (FIG.  12 ), to the ground clip  1800  (FIGS.  18 A-D). 
     Ground Clip 
     FIGS. 18A-D illustrate the ground clip  1800 , which has a “U”-shaped insert  1810 , a jumper pad  1820  and ground pin contacts  1870 . The insert  1810  fits into housing socket structure  1360  (FIGS. 13A-D) that retains the ground clip  1800 . One end of a ground jumper  1220  (FIG. 12) is resistance welded to the jumper pad  1820 , electrically connecting the ground clip  1800  to a ground bar  1700  (FIGS.  17 A-D). The ground pin contacts  1870  accept a standard AC plug ground pin inserted into the adapter socket  1150  (FIG.  11 F). 
     Prongs 
     FIGS. 19A-E illustrate the prongs  1900 , which include a neutral prong  1902  and a hot prong  1904 . The prongs  1900  each have a jumper pad  1910 , a spring bar  1920 , a contact holder  1930  and a crossbar  1950 . The jumper pad  1910  attaches one end of either a neutral  1232  or hot jumper  1234  (FIG.  12 ), which is resistance welded to the pad  1910  to provide a conduction path to neutral  2000  (FIGS. 20A-D) or hot clips  2100  (FIGS.  21 A-D). The spring bar  1920  has a static curvature that maintains a prong  1900  in a retracted position within the plug  1200  (FIGS.  11 A-F). A slide  2200  (FIGS. 22A-D) mounted between the prongs  1900  pushes against, and temporarily straightens, the spring bar  1920  to move the prong  1900  to an extended position. The contact holder  1930  has a hole  1932  in which a contact  1282 ,  1284  (FIG. 12) is swaged. The contact holder  1930  passes through a receptacle access aperture  520  (FIGS. 2A-E) when the prong  1900  is extended, connecting the plug contact  1282 ,  1284  (FIG. 12) with an outlet contact  382 ,  383  (FIG.  3 A). The crossbar  1950  connects the jumper pad  1910  to the spring bar  1920  and supports the prong  1900  within the probe  1310  (FIGS.  11 A-F). 
     Neutral Clip 
     FIGS. 20A-D illustrate the neutral clip  2000 , which has a neutral blade contact  2010 , a jumper pad  2020  and ends  2030 ,  2040 . The blade contact  2010  accepts a standard AC plug neutral blade inserted into the adapter socket  1150  (FIG.  11 F). One end of a neutral jumper  1232  is resistance welded to the jumper pad  2020 , electrically connecting the neutral clip  2000  to a neutral prong  1902  (FIGS.  19 A-D). The ends  2030 ,  2040  insert into the housing front half  1300  (FIGS. 13A-D) and back half  1400  (FIGS.  14 A-D), respectively, retaining the neutral clip  2000 . 
     Hot Clip 
     FIGS. 21A-D illustrate the hot clip  2100 , which has a hot blade contact  2110 , a jumper pad  2120  and ends  2130 ,  2140 . The blade contact  2110  accepts a standard AC plug hot blade inserted into the adapter socket  1150  (FIG.  11 F). One end of a hot jumper  1234  is resistance welded to the jumper pad  2120 , electrically connecting the hot clip  2100  to a hot prong  1904  (FIG.  19 E). The ends  2130 ,  2140  insert into the housing front half  1300  (FIGS. 13A-D) and back half  1400  (FIGS.  14 A-D), respectively, retaining the hot clip  2100 . 
     Slide 
     FIGS. 22A-D illustrate the slide  2200 , which has a post  2270  with a piston  2210  mounted on one end. The post end  2272  opposite the piston  2210  is open and accommodates the finger hold stem  1570  (FIGS.  15 A-D). The piston  2210  is slidably retained within the probe  1310  (FIGS. 11A-F) and has sides  2212  that press against the prong spring bars  1920  (FIGS.  19 A-E). The piston  2210  has a generally triangular shape compatible with the probe  1310  (FIGS. 11A-F) cross-section. The position of the connected finger hold  1500  (FIGS. 15A-D) controls the position of the piston  2210 . The piston  2210  is proximate the probe face  1311  (FIGS. 11A-F) in the plug locked position (FIGS. 11A-B) and distal the probe face  1311  (FIGS. 11A-F) and proximate the probe back face  1318  in the plug unlocked position (FIGS.  11 C-D). The piston face  2214  has two elongated blocks  2216  extending along the base and a vertical slot  2218  between the blocks  2216 . The blocks  2216  fit within the probe face openings  1315  (FIGS. 13A-D) in the plug locked position, forcing the prongs  1900  (FIGS. 19A-E) to extend from the probe  1310  (FIGS.  11 A-F). In the plug unlocked position, the piston is distal the prong spring bars  1920  (FIGS.  19 A-E), allowing the spring bars  1920  (FIGS. 19A-E) to retract the prongs  1900  into the probe  1310  (FIGS.  11 A-F). The vertical slot  2218  mates with a corresponding guide within the probe  1310 . 
     Although the locking plug was described with respect to a finger hold prong actuator, another embodiment is a plug with side-mounted push-buttons. When pressed, the buttons would squeeze the prongs together, moving the prongs to the retracted position. The buttons would be held down to insert the plug and released to lock the plug in an outlet. Further, the locking plug was described as an adapter plug, which has a socket that accepts a standard AC plug. Another embodiment would be a locking plug with a directly wired power cord. 
     The outlet was described in terms of duplex receptacles. One of ordinary skill in the art will recognize that the scope of the present invention would also include a single receptacle outlet or outlets of more than two receptacles or ganged outlets. 
     Both the locking plug and the covered outlet were described as having jumper wires to internally connect various contacts and conductive elements. In an alternative embodiment, each jumper is replaced with a solid stamped buss. In the outlet, the solid stamped busses could be implemented with breakaway portions to electrically isolate the two receptacles and allowing the outlet to be configured as either full-hot or half-hot. 
     One of ordinary skill in the art will recognize that a locking plug or adapter plug can also be configured to extend parallel to the case or at a variety of other angles. Further, plugs and corresponding receptacles and covers can have a number of cross-sectional shapes other than the generally triangular shaped described above, all within the scope of the present invention. 
     The safety electrical connection system has been disclosed in detail in connection with various embodiments of the present invention. These embodiments are disclosed by way of examples only and are not to limit the scope of the present invention, which is defined by the claims that follow. One of ordinary skill in the art will appreciate many variations and modifications within the scope of this invention.