Patent Publication Number: US-2022239039-A1

Title: Electrical receptacle with locking feature

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a U.S. continuation patent application of, and claims priority under 35 U.S.C. § 120 to, U.S. nonprovisional patent application Ser. No. 17/106,711, filed Nov. 30, 2020, which &#39;711 application published as U.S. Patent Application Publication No. US 2021/0083430 A1 on Mar. 18, 2021 and issued as U.S. Pat. No. 11,322,891 on May 3, 2022, which &#39;711 application, the publication thereof, and the patent issuing therefrom are each incorporated herein by reference in their entirety, and which &#39;711 is a U.S. continuation patent application of, and claims priority under 35 U.S.C. § 120 to, U.S. nonprovisional patent application Ser. No. 16/743,798, filed Jan. 15, 2020, which &#39;798 application published as U.S. Patent Application Publication No. US 2020/0153166 A1 on May 14, 2020 and issued as U.S. Pat. No. 10,855,030 on Dec. 1, 2020, which &#39;798 application, the publication thereof, and the patent issuing therefrom are each incorporated herein by reference in their entirety, and which &#39;798 is a U.S. continuation patent application of, and claims priority under 35 U.S.C. § 120 to, U.S. nonprovisional patent application Ser. No. 16/267,633, filed Feb. 5, 2019, which &#39;633 application published as U.S. Patent Application Publication No. US 2019/0245305 A1 on Aug. 8, 2019 and issued as U.S. Pat. No. 10,547,145 on Jan. 28, 2020, which &#39;633 application, the publication thereof, and the patent issuing therefrom are each incorporated herein by reference in their entirety, and which &#39;633 application is a U.S. nonprovisional patent application of, and claims priority under 35 U.S.C. § 119(e) to, U.S. provisional patent application Ser. No. 62/626,346, filed Feb. 5, 2018, which &#39;346 application is incorporated by reference herein in its entirety, and which &#39;633 application is a U.S. nonprovisional patent application of, and claims priority under 35 U.S.C. § 119(e) to, U.S. provisional patent application Ser. No. 62/732,872, filed Sep. 18, 2018, which &#39;872 application is incorporated by reference herein in its entirety. Additionally, the entirety of the following commonly-assigned U.S. patent application, its publication and the patent issuing therefore are each incorporated by reference herein: U.S. nonprovisional patent application Ser. No. 14/732,234, filed Jun. 5, 2015, which &#39;234 application published on Dec. 10, 2015 as U.S. Patent Application Publication No. US 2015/0357758 A1 and issued on Dec. 27, 2016 as U.S. Pat. No. 9,531,126. 
    
    
     COPYRIGHT STATEMENT 
     All of the material in this patent document is subject to copyright protection under the copyright laws of the United States and other countries. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in official governmental records but, otherwise, all other copyright rights whatsoever are reserved. 
     BACKGROUND OF THE PRESENT INVENTION 
     Field of the Present Invention 
     The present invention relates generally to power cords and their connectors, and, in particular, to plug retention mechanisms for electrical receptacles. 
     Background 
     Power cords are ubiquitous in the developed world, providing power from a conventional distribution system to electrically-powered devices of a very wide variety of types. Each power cord usually includes a cable with a plug or other electrical fitting at each end. For residential devices, most power cords utilize a plug having a standard size and arrangement of electrical connectors, with the particular standard being specific to a particular country or set of countries. Power cords for devices having electrical requirements that are different from that standard frequently utilize different sizes and/or arrangements to ensure that the wrong plug is not connected thereto. 
     In the computer industry, specialized plug/receptacle pairs are likewise used for various electrical needs. The plug/receptacle pairs are typically selected from conventional receptacle designs such as those set forward by IEC 60320. According to the standard, the specifications of corresponding female and male pairs of electrical connectors (such as C13 and C14 types) are defined such that the physical attributes of those connectors are standardized. By way of example,  FIG. 1A  is a front isometric view of a conventional female electrical receptacle. The illustrated receptacle is in the form of a panel-mount C13-type receptacle, but it will be appreciated that various other receptacle types with different electrical connection configurations also exist. The receptacle includes a female fitting surrounded by a socket. Female electrical contacts are contained within the female fitting. A plate may be provided on the front of, and typically integral with, the socket. The receptacle may be mounted in various fixtures using screws, solder joints, or in other known ways; the receptacle (and especially the socket) may include additional features to facilitate such mounting. The female electrical receptacle is adapted to receive a corresponding male electrical receptacle (not shown in  FIG. 1A ). Such a male receptacle would typically include a male fitting from which male electrical contacts extend as well as a socket surrounding the male electrical contacts. 
     A common problem within the computer industry and generally is the accidental dislocation of a particular plug (connector) from a receptacle. Because each plug commonly has a cord extending therefrom, it is easy to generate enough force, accidentally, to loosen the plug in the receptacle or even to pull it out entirely. Contributing to the problem is the fact that many connectors are designed to be removed easily by hand, which means that the force necessary to loosen or remove the plug is often not particularly great. The problem can be particularly vexing around power distribution units (PDUs). 
     As a result, many devices and techniques have been used to hold plugs in place. Some such devices include plugs with threaded fittings (e.g., screws) that may be coupled to corresponding fittings on the receptacle. Others involve a retention element installed on the cord that can be attached to a stud or other element of the receptacle or PDU (e.g., bars or brackets fastened to the receptacle or PDU once the plug or plugs are in place). However, these devices and techniques present additional challenges that must be overcome, such as the need for special connector designs as well as their overall difficulty of use (particularly with regard to challenges associated with installation and removal). 
     Another known device for retaining a plug in position involves a receptacle that includes an integrated lock housing, such as the device shown in  FIG. 1B . In  FIG. 1B , a lock housing P 20  extends from the front of the electrical receptacle P 10 . As the plug (not shown in  FIG. 1B ) is guided into the lock housing opening P 30  and establishes an electrical connection, lock tabs P 26  on the lock housing P 20  snap into place against the plug, thereby retaining the plug in a locked position. However, as should also be apparent from  FIG. 1B , the lock housing P 20  extends the height of the receptacle by a significant margin, which may inhibit use of the receptacle in certain environments where space is limited. Furthermore, the fact of the lock housing P 20  being integrated with the receptacle means that the receptacle must be entirely removed in order to convert the receptacle from a “locking” receptacle to a “non-locking” receptacle. 
     Thus, a need exists for an electrical receptacle locking solution that does not significantly impact the overall footprint and spatial requirements of the electrical receptacle. Furthermore, a need exists for an electrical receptacle locking solution where the receptacle can be populated with a locking feature without the receptacle needing to be removed or uninstalled. These, and other needs, are addressed by one or more aspects of the present invention. 
     SUMMARY OF THE PRESENT INVENTION 
     Some exemplary embodiments of the present invention may overcome one or more of the above disadvantages and other disadvantages not described above, but the present invention is not required to overcome any particular disadvantage described above, and some exemplary embodiments of the present invention may not overcome any of the disadvantages described above. 
     Broadly defined, the present invention according to one aspect includes an electrical receptacle unit with locking feature. The electrical receptacle unit includes a receptacle adapted to be electrically connected to a source of electricity. The receptacle includes a socket and a plate disposed at a front of the socket. The electrical receptacle unit further includes a locking bracket positioned relative to the plate. The locking bracket is configured to be transitionable between an unlocked configuration, whereby a plug electrically seated within the socket is unobstructed by the locking bracket, and a locked configuration, whereby the plug electrically seated within the socket is obstructed by the locking bracket. 
     In a feature of this aspect, the locking bracket includes a generally flat central portion having a lock tab extending therefrom, and, in the locked configuration, the lock tab obstructs a portion of the plug so that the plug cannot be removed from the socket. 
     In another feature of this aspect, the lock tab extends from the central portion at an angle. 
     In another feature of this aspect, the locking bracket includes a support arm at each side of the central portion. 
     In another feature of this aspect, a distal end of each support arm is received within a corresponding notched area of the plate. In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the receptacle in the stacking direction. 
     In another feature of this aspect, each support arm is secured to the plate via a hinge pin. In another feature of this aspect, the locking bracket is pivotable between the unlocked and locked configurations about the hinge pins. 
     In another feature of this aspect, the locking bracket further includes a pair of deflectable positioning arms extending away from the central portion. In another feature of this aspect, each positioning arm includes a bent portion that engages the plate at a respective side thereof. In another feature of this aspect: in the unlocked configuration, each bent portion is received within a respective first transverse groove arranged on the plate; in the locked configuration, each bent portion is received within a respective second transverse groove arranged on the plate; and the second transverse groove is spaced apart from the first transverse groove. In another feature of this aspect, the locking bracket is transitionable between the unlocked and locked configurations by laterally sliding the locking bracket so that the bent portions of the positioning arms move from the first transverse groove to the second transverse groove. 
     In another feature of this aspect, the locking bracket includes a grip tab extending from a side of the central portion opposite to that of the lock tab. 
     In another feature of this aspect, the locking bracket is made from a thin metal material. 
     In another feature of this aspect, the locking bracket includes at least one spring anchored to the plate that biases the locking bracket in favor of the locked configuration. 
     In another feature of this aspect, the plate includes a cavity adapted to receive a protrusion of the locking bracket when in the locked configuration. 
     Broadly defined, the present invention according to another aspect includes an electrical receptacle unit with locking feature. The electrical receptacle unit includes a receptacle adapted to be electrically connected to a source of electricity. The receptacle includes a socket and a plate disposed at a front of the socket. The electrical receptacle unit further includes a locking bracket that is pivotably secured at opposite sides of the plate and biased in favor of a locked position, whereby a lock tab obstructs a portion of the plug so that the plug cannot be removed from the socket. 
     In a feature of this aspect, the lock tab extends from a central portion of the locking bracket at an angle. In another feature of this aspect, the locking bracket includes a support arm at each side of the central portion, each support arm including an inwardly-oriented protrusion. In another feature of this aspect, the locking bracket is biased in favor of the locked position via one or more springs. In another feature of this aspect, each of the one or more springs is anchored between one of the support arms and the plate. In another feature of this aspect, a distal end of each support arm is received within a corresponding notched area of the plate. In another feature of this aspect, each support arm includes an inwardly-oriented protrusion that is received within a cavity of the corresponding notched area of the plate when the locking bracket is in the locked position. In another feature of this aspect, each protrusion is received within the cavity via snap-fit. In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the receptacle in the stacking direction. 
     In another feature of this aspect, the locking bracket is pivotably secured to the plate via one or more hinge pins. 
     Broadly defined, the present invention according to another aspect includes an electrical receptacle unit with locking feature substantially as shown and described. 
     Broadly defined, the present invention according to another aspect includes a method of securing a plug to an electrical receptacle unit. The method includes providing a receptacle including a socket, a plate disposed at a front of the socket, and a locking bracket positioned relative to the plate; seating a plug within the socket; and transitioning the locking bracket from an unlocked configuration, whereby the plug is unobstructed by the locking bracket, and a locked configuration, whereby the plug is obstructed by the locking bracket. 
     In a feature of this aspect, the transitioning step includes pivoting the locking bracket about one or more hinge pins so that a lock tab extending from the locking bracket obstructs a ledge on the plug. 
     In another feature of this aspect, the transitioning step includes laterally sliding the locking bracket so that a lock tab extending from the locking bracket obstructs a ledge on the plug. 
     In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the receptacle in the stacking direction. 
     In another feature of this aspect, the locking bracket is a spring-biased locking bracket. 
     Broadly defined, the present invention according to another aspect includes a method of securing a plug to an electrical receptacle unit substantially as shown and described. 
     Broadly defined, the present invention according to another aspect includes an electrical receptacle unit with locking feature. The electrical receptacle unit with locking feature includes a receptacle adapted to be electrically connected to a source of electricity. The receptacle includes an electrical fitting having electrical contacts contained therein and/or extending therefrom, a socket surrounding the electrical fitting, and a plate disposed at a front of the socket. The electrical receptacle unit with locking feature further includes a locking bracket that includes a central portion having first and second ends, a lock tab extending from a side of the central portion, and a pair of support arms, each extending forwardly from a respective one of the first and second ends. The locking bracket is pivotably secured to the plate, with at least a portion of each support arm positioned within a respective notched area of the plate. The locking bracket is pivotable relative to the plate between a first position, whereby a plug electrically seated within the socket is unobstructed, and a second position, whereby the plug electrically seated within the socket is obstructed from removal by the lock tab. 
     In a feature of this aspect, the receptacle is a panel-mount receptacle. In another feature of this aspect, the socket of the receptacle includes walls, at least one of which walls includes a locking tab that retains the receptacle in a fixture. 
     In another feature of this aspect, the electrical fitting is a female electrical fitting having female electrical contacts contained therein. In another feature of this aspect, the plug and receptacle are of a C13/C14-type. In another feature of this aspect, the locking bracket includes a grip tab extending from a side of the central portion opposite to that of the lock tab. In another feature of this aspect, the locking bracket is made from a metal material. In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the receptacle in the stacking direction. In another feature of this aspect, the lock tab extends from the central portion at an angle. 
     In another feature of this aspect, each of the pair of support arms is secured to the plate via a respective hinge pin, each of which extends from a respective one of the notched areas of the plate and through an aperture of the portion of the support arm positioned therein. In another feature of this aspect, the locking bracket is pivotable between the first and second positions about the hinge pins. 
     In another feature of this aspect, the locking bracket further includes at least one spring anchored between one of the pair of support arms and the plate. In another feature of this aspect, the at least one spring biases the locking bracket in favor of the second position. In another feature of this aspect, each support arm includes an inwardly-oriented protrusion. In another feature of this aspect, each inwardly-oriented protrusion is received within a cavity of the corresponding notched area of the plate when the locking bracket is in the second position. In another feature of this aspect, each inwardly-oriented protrusion is received within the corresponding cavity via snap-fit. 
     Broadly defined, the present invention according to another aspect includes a method of securing a plug to an electrical receptacle unit. The method includes providing an electrical receptacle unit having a female electrical fitting with a surrounding receptacle unit socket, a plate disposed at a front of the receptacle unit socket, and a locking bracket having first and second support arms arranged to extend forwardly from opposite sides of a central portion, wherein the locking bracket is pivotably secured to the plate via one or more hinge pins, wherein at least a portion of each support arm is received within a respective notched area of the plate. The method further includes providing a plug having a male electrical fitting with male electrical contacts extending therefrom and a plug socket that surrounds the male electrical contacts, positioning the plug within the receptacle unit socket to establish an electrical connection therewith, and pivoting the locking bracket relative to the plate from a first position, whereby the plug is unobstructed, to a second position, whereby a portion of the locking bracket obstructs the plug from removal. 
     In a feature of this aspect, the plug includes a ledge formed at a junction of the male electrical fitting and the plug socket, and, when the locking bracket is pivoted from the first position to the second position, a lock tab extending forwardly from the central portion of the locking bracket is positioned over the ledge to obstruct the plug. 
     In another feature of this aspect, the locking bracket further includes at least one spring anchored between one of the pair of support arms and the plate, and the at least one spring biases the locking bracket in favor of the second position. 
     In another feature of this aspect, each support arm includes an inwardly-oriented protrusion, each notched area of the plate includes a cavity, and, when the locking bracket is pivoted from the first position to the second position, each inwardly-oriented protrusion is received, via snap-fit, within the corresponding cavity of the plate. 
     In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the electrical receptacle unit in the stacking direction. 
     Broadly defined, the present invention according to another aspect includes an electrical receptacle unit with locking feature. The electrical receptacle unit with locking feature includes a receptacle adapted to be electrically connected to a source of electricity. The receptacle includes an electrical fitting having electrical contacts contained therein and/or extending therefrom, a socket surrounding the electrical fitting, and a plate disposed at a front of the socket. The electrical receptacle unit with locking feature further includes a locking bracket that includes a central portion having first and second ends, a lock tab extending forwardly from a side of the central portion, and a pair of support arms, each extending forwardly from a respective one of the first and second ends. The locking bracket is slidably engaged with the plate, with at least a portion of each support arm positioned within a respective notched area of the plate. The locking bracket is laterally maneuverable relative to the plate between a first position, whereby a plug electrically seated within the socket is unobstructed, and a second position, whereby the plug electrically seated within the socket is obstructed from removal by the lock tab. 
     In a feature of this aspect, the receptacle is a panel-mount receptacle. In another feature of this aspect, the socket of the receptacle includes walls, at least one of which walls includes a locking tab that retains the receptacle in a fixture. 
     In another feature of this aspect, the electrical fitting is a female electrical fitting having female electrical contacts contained therein. In another feature of this aspect, the plug and receptacle are of a C13/C14-type. 
     In another feature of this aspect, an inwardly-oriented hook tab is disposed at a distal end of each support arm and is received within the corresponding notched area of the plate. In another feature of this aspect, each inwardly-oriented hook tab is maneuverable from one end of the corresponding notched area to an opposite end of the corresponding notched area as the locking bracket is transitioned from the first position to the second position. 
     In another feature of this aspect, the locking bracket includes a grip tab extending from a side of the central portion opposite to that of the lock tab. In another feature of this aspect, the locking bracket is made from a metal material. In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the receptacle in the stacking direction. 
     In another feature of this aspect, the locking bracket further includes a pair of deflectable positioning arms, each extending forwardly from the central portion at a location that is generally adjacent to, but spaced inwardly from, a respective one of the pair of support arms. In another feature of this aspect, each deflectable positioning arm includes a bent portion that engages a front-facing surface of the plate. 
     In another feature of this aspect, when the locking bracket is in the first position, each bent portion is seated within a respective one of a first aligned pair of transverse grooves in the front-facing surface of the plate, when the locking bracket is in the second position, each bent portion is seated within a respective one of a second aligned pair of transverse grooves in the front-facing surface of the plate, and the second aligned pair of transverse grooves is spaced apart from the first aligned pair of transverse grooves. 
     Broadly defined, the present invention according to another aspect includes a method of securing a plug to an electrical receptacle unit. The method includes providing an electrical receptacle unit having a female electrical fitting with a surrounding receptacle unit socket, a plate disposed at a front of the receptacle unit socket, and a locking bracket having first and second support arms arranged to extend forwardly from opposite sides of a central portion, wherein the locking bracket is slidably engaged with the plate, with at least a portion of each support arm received within a respective notched area of the plate. The method further includes providing a plug having a male electrical fitting with male electrical contacts extending therefrom and a plug socket that surrounds the male electrical contacts, positioning the plug within the receptacle unit socket to establish an electrical connection therewith, and laterally maneuvering the locking bracket relative to the plate from a first position, whereby the plug is unobstructed, to a second position, whereby a portion of the locking bracket obstructs the plug from removal. 
     In a feature of this aspect, the plug includes a ledge formed at a junction of the male electrical fitting and the plug socket, and, when the locking bracket is laterally maneuvered from the first position to the second position, a lock tab extending forwardly from the central portion of the locking bracket is positioned over the ledge to obstruct the plug. 
     In another feature of this aspect, the locking bracket includes a pair of deflectable positioning arms, each of the pair of deflectable positioning arms extends forwardly from the central portion at a location that is generally adjacent to, but spaced inwardly from, a respective one of the pair of support arms, and each of the pair of deflectable positioning arms includes a bent portion that engages a front-facing surface of the plate. 
     In another feature of this aspect, when the locking bracket is in the first position, the bent portion of each of the pair of positioning arms is seated within a respective one of a first aligned pair of transverse grooves in the front-facing surface of the plate, when the locking bracket is laterally maneuvered from the first position to the second position, each of the pair of deflectable positioning arms is deflected by the plate, and each of the bent portions is transitioned from the respective one of the first aligned pair of transverse grooves to a respective one of a second aligned pair of transverse grooves in the front-facing surface of the plate, and the second aligned pair of transverse grooves is spaced apart from the first aligned pair of transverse grooves. 
     In another feature of this aspect, laterally maneuvering the locking bracket from the first position to the second position includes applying a force to the locking bracket that is sufficient to cause each of the pair of deflectable positioning arms to be deflected. 
     In another feature of this aspect, a length of the locking bracket does not extend beyond a footprint of the electrical receptacle unit in the stacking direction. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features, embodiments, and advantages of the present invention will become apparent from the following detailed description with reference to the drawings, wherein: 
         FIG. 1A  is a front isometric view of a conventional female electrical receptacle; 
         FIG. 1B  is a front isometric view of a known electrical receptacle unit with an integrated locking feature; 
         FIG. 2  is a front isometric view of an electrical receptacle unit with locking feature in accordance with a preferred embodiment of the present invention; 
         FIG. 3  is a front isometric view of the electrical receptacle unit of  FIG. 2  shown mounted in a fixture, wherein the fixture is illustrated schematically; 
         FIG. 4  is a front isometric view of the electrical receptacle unit of  FIG. 2 , shown with an unconnected power cord; 
         FIG. 5A  is a front isometric view of the electrical receptacle unit of  FIG. 2 , shown with the power cord connected thereto in an unlocked position; 
         FIG. 5B  is a front isometric view of the electrical receptacle unit of  FIG. 2 , shown with the power cord connected thereto in a locked position; 
         FIG. 6A  is a top view of the electrical receptacle unit and plug of  FIG. 4 ; 
         FIG. 6B  is a top cross-sectional view of the electrical receptacle unit and plug of  FIG. 4 , taken along line  6 B- 6 B; 
         FIG. 6C  is a top cross-sectional view of the electrical receptacle unit and plug of  FIG. 5A , taken along line  6 C- 6 C; 
         FIG. 6D  is a top cross-sectional view of the electrical receptacle unit and plug of  FIG. 6C , shown with the locking bracket being transitioned from the unlocked position to the locked position; 
         FIG. 6E  is a top cross-sectional view of the electrical receptacle unit and plug of  FIG. 5B , taken along line  6 E- 6 E; 
         FIG. 6F  is a top cross-sectional views of the electrical receptacle unit and plug of  FIG. 6E , shown with the locking bracket being transitioned from the locked position to the unlocked position; 
         FIG. 7  is a front isometric view of another electrical receptacle unit with locking feature in accordance with a preferred embodiment of the present invention; 
         FIG. 8  is a front isometric view of the electrical receptacle unit of  FIG. 7  shown mounted in a fixture, wherein the fixture is illustrated schematically; 
         FIG. 9  is a front isometric view of the electrical receptacle unit of  FIG. 7 , shown with an unconnected power cord; 
         FIG. 10A  is a front isometric view of the electrical receptacle unit of  FIG. 7 , shown with a power cord connected thereto in an unlocked position; 
         FIG. 10B  is a front isometric view of the electrical receptacle unit of  FIG. 7 , shown with the power cord connected thereto in a locked position; 
         FIG. 11A  is a top view of the electrical receptacle unit and plug of  FIG. 9 ; 
         FIG. 11B  is a top view of the electrical receptacle unit and plug of  FIG. 10A ; 
         FIG. 11C  is a top view of the electrical receptacle unit and plug of  FIG. 10B ; 
         FIG. 11D  is a top cross-sectional view of the electrical receptacle unit and plug of  FIG. 10B , taken along line  11 D- 11 D; 
         FIG. 12A  is a front isometric view of another electrical receptacle unit with locking feature in accordance with a preferred embodiment of the present invention; 
         FIG. 12B  is a front view of the electrical receptacle unit of  FIG. 12A ; 
         FIG. 13  is a front isometric view of the electrical receptacle unit of  FIG. 12A  shown mounted in a fixture, wherein the fixture is illustrated schematically; 
         FIG. 14  is a front isometric view of the electrical receptacle unit of  FIG. 12A , shown with an unconnected power cord; 
         FIG. 15A  is a front isometric view of the electrical receptacle unit of  FIG. 12A , shown with a power cord connected thereto; 
         FIG. 15B  is a front isometric view of the electrical receptacle unit of  FIG. 12A , shown with the power cord connected thereto in a locked position; 
         FIG. 16A  is a top view of the electrical receptacle unit and plug of  FIG. 14 ; 
         FIG. 16B  is a top view of the electrical receptacle unit and plug of  FIG. 15A ; 
         FIG. 16C  is a top view of the electrical receptacle unit and plug of  FIG. 15B ; 
         FIG. 16D  is a top cross-sectional view of the electrical receptacle unit and plug of  FIG. 15B , taken along line  16 D- 16 D; 
         FIG. 17A  is a top view of the electrical receptacle unit and plug of  FIG. 5A , illustrating a height of the locking bracket in the unlocked position; 
         FIG. 17B  is a top view of the electrical receptacle unit and plug of  FIG. 10A , illustrating a height of the locking bracket in the unlocked position; 
         FIG. 18A  is an end view of the electrical receptacle unit and plug of  FIG. 5B , illustrating a footprint of the locking bracket in the stacking direction; and 
         FIG. 18B  is an end view of the electrical receptacle unit and plug of  FIG. 10B , illustrating a footprint of the locking bracket in the stacking direction. 
     
    
    
     DETAILED DESCRIPTION 
     As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art (“Ordinary Artisan”) that the present invention has broad utility and application. Furthermore, any embodiment discussed and identified as being “preferred” is considered to be part of a best mode contemplated for carrying out the present invention. Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure of the present invention. As should be understood, any embodiment may incorporate only one or a plurality of the above-disclosed aspects of the invention and may further incorporate only one or a plurality of the above-disclosed features. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present invention. 
     Accordingly, while the present invention is described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present invention, and is made merely for the purposes of providing a full and enabling disclosure of the present invention. The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded the present invention, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection afforded the present invention be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself. 
     Thus, for example, any sequence(s) and/or temporal order of steps of various processes or methods that are described herein are illustrative and not restrictive. Accordingly, it should be understood that, although steps of various processes or methods may be shown and described as being in a sequence or temporal order, the steps of any such processes or methods are not limited to being carried out in any particular sequence or order, absent an indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and orders while still falling within the scope of the present invention. Accordingly, it is intended that the scope of patent protection afforded the present invention is to be defined by the appended claims rather than the description set forth herein. 
     Additionally, it is important to note that each term used herein refers to that which the Ordinary Artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaning of a term used herein—as understood by the Ordinary Artisan based on the contextual use of such term—differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the Ordinary Artisan should prevail. 
     Regarding applicability of 35 U.S.C. § 112, ¶6, no claim element is intended to be read in accordance with this statutory provision unless the explicit phrase “means for” or “step for” is actually used in such claim element, whereupon this statutory provision is intended to apply in the interpretation of such claim element. 
     Furthermore, it is important to note that, as used herein, “a” and “an” each generally denotes “at least one,” but does not exclude a plurality unless the contextual use dictates otherwise. Thus, reference to “a picnic basket having an apple” describes “a picnic basket having at least one apple” as well as “a picnic basket having apples.” In contrast, reference to “a picnic basket having a single apple” describes “a picnic basket having only one apple.” 
     When used herein to join a list of items, “or” denotes “at least one of the items,” but does not exclude a plurality of items of the list. Thus, reference to “a picnic basket having cheese or crackers” describes “a picnic basket having cheese without crackers,” “a picnic basket having crackers without cheese,” and “a picnic basket having both cheese and crackers.” Finally, when used herein to join a list of items, “and” denotes “all of the items of the list.” Thus, reference to “a picnic basket having cheese and crackers” describes “a picnic basket having cheese, wherein the picnic basket further has crackers,” as well as describes “a picnic basket having crackers, wherein the picnic basket further has cheese.” 
     Referring now to the drawings, in which like numerals represent like components throughout the several views, one or more preferred embodiments of the present invention are next described. The following description of one or more preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
       FIG. 2  is a front isometric view of an electrical receptacle unit  10  with locking feature in accordance with a preferred embodiment of the present invention. As shown therein, the electrical receptacle unit  10  includes a female electrical fitting  12 , a surrounding socket  13 , and a plate  14  disposed at a front of the surrounding socket  13 . The illustrated female fitting  12  is in the form of a panel-mount C13-type receptacle, but it will be appreciated that various other receptacle types with different electrical connection configurations also exist. In at least some embodiments, the plate  14  is integral with the socket  13 , but, in other embodiments, the plate  14  may be attached during or after manufacturing. Further, in some contemplated embodiments, the plate is integral with, or attached to, the electrical fitting. 
       FIG. 3  is a front isometric view of the electrical receptacle unit of  FIG. 2  shown mounted in a fixture  100 , wherein the fixture  100  is illustrated schematically. The receptacle unit  10  may be mounted in various fixtures using screws, solder joints, or in other known ways; the receptacle (and especially the socket) may include additional features to facilitate such mounting. In accordance with one or more preferred approaches to mounting the receptacle unit  10 , the walls of the socket  13  may include locking tabs  15  (as can be seen in  FIG. 2 ) that are naturally depressed as the socket  13  is maneuvered into position in the fixture  100 , but are biased to spring outward when the socket  13  is fully inserted into such fixture  100 , thereby holding the receptacle unit  10  in place in the fixture  100 . 
     As can be seen in  FIGS. 2 and 3 , the electrical receptacle unit  10  further includes a locking bracket  16  that is slidably engaged with the plate  14 . The locking bracket includes a flat central portion  19  with a pair of support arms  17  arranged at opposite sides that extend toward and fit against sides of the plate  14 . As will be explained in greater detail below, the locking bracket  14  is capable of being maneuvered laterally toward the plate  14  to secure, or lock, a plug that is received in the electrical receptacle unit  10 . 
     In at least some embodiments, the locking bracket  16  is manufactured separately from the electrical receptacle unit  10  and is fastened thereto. It is further contemplated that the locking bracket  16  can be pre-installed or can be installed on the receptacle unit  10  after the receptacle unit  10  has been put into use. In this latter regard, the support arms  17  need only be deflected far enough away from one another to be fit at either side of the plate  14 . It is contemplated that deflection of the support arms  17  can be accomplished with the aid of a flat head screwdriver, which can be used as a lever against one of the support arms  17 . The locking bracket  16  can likewise be uninstalled from the receptacle unit  10  in a similar manner without the receptacle unit  10  needing to be removed or uninstalled. In at least some embodiments, it is contemplated that the locking bracket  16  is made from a durable solid material, such as a hardened thin metal material, that is capable of deflection and exhibits a resilient quality. 
     The female electrical fitting  12  is adapted to receive a corresponding male electrical fitting. In this regard,  FIG. 4  is a front isometric view of the electrical receptacle unit  10  of  FIG. 2 , shown with an unconnected power cord. The power cord includes a plug  40  attached to the end of an electrical cable  44 . The plug  40  includes a male fitting  42 , from which male electrical contacts extend as well as a socket  43  surrounding the male electrical contacts. A ledge  34  is formed at the junction of the male fitting  42  and the socket  43 , where trailing edges of the socket  43  extend beyond leading edges of the male fitting  42  (as the plug  40  is received in the receptacle unit  10 ). In at least some embodiments, the plug  40  is of conventional construction, as is the electrical cable  44  to which it is attached. 
     The plug  40  may be inserted into the receptacle unit  10  such that a conventional electrical connection is established and maintained. In this regard,  FIG. 5A  is a front isometric view of the electrical receptacle unit  10  of  FIG. 2 , shown with the power cord connected thereto in an unlocked position, and  FIG. 5B  is a front isometric view of the electrical receptacle unit  10  of  FIG. 2 , shown with the power cord connected thereto in a locked position. When fully seated in the socket  13 , the plug  40  can be retained by shifting the locking bracket  16  toward the plate  14  so that an inward-facing lock tab  18  (extending inwardly from the central portion  19  of the locking bracket  16 ) rests over the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 . In so doing, the lock tab  18  obstructs the plug  40  such that it will not become “unplugged” or otherwise disconnected accidentally from the socket  13 , thereby effectively locking the plug  40  into position. 
       FIGS. 6A-6F  are a series of top views of the electrical receptacle unit  10  and plug  40  of  FIGS. 4, 5A and 5B  that illustrate locking and unlocking the locking bracket  16  relative to the plug  40 . In  FIGS. 6A-6F , solid arrows are sometimes used to illustrate movement of various components of the locking bracket  16 , whether by an applied force or by reaction to an applied force. 
       FIG. 6A  is a top view of the electrical receptacle unit  10  and plug  40  of  FIG. 4 , and  FIG. 6B  is a top cross-sectional view of the electrical receptacle unit  10  and plug  40  of  FIG. 4 , taken along line  6 B- 6 B. In  FIGS. 6A and 6B , the locking bracket  16  is arranged in the unlocked position so that the plug  40  can be received in the socket  13  of the electrical receptacle unit  10 . With additional reference to  FIG. 4 , the support arms  17  of the locking bracket  16  are arranged against the plate  14  of the receptacle unit  10  along lateral edges thereof. Each support arm  17  includes a hook tab  25  at a distal end. The hook tab  25  is received within a corresponding notched area  26  at opposed lateral edges of the plate  14 . As the locking bracket  16  is transitioned to the locked position, the hook tabs  25  slide from one end of the respective notched area  26  to the opposite end. In either the unlocked or locked position, it is contemplated that the hook tabs  25  remain within the respective notched areas  26 , thereby assisting with keeping the locking bracket  16  secure and/or aligned relative to the receptacle unit  10 . 
     As further shown in  FIGS. 6A and 6B , the locking bracket  16  further includes a grip tab  23  that extends outwardly and upwardly from a side of the central portion  19 , opposite from the lock tab  18 . The grip tab  23  provides a surface by which the locking bracket  16  can be grasped and maneuvered by a user, such as by holding the grip tab  23  between the user&#39;s thumb and forefinger. In this manner, the grip tab  23  facilitates a user having the ability to transition the locking bracket  16  manually between the unlocked and locked positions. 
       FIG. 6C  is a top cross-sectional view of the electrical receptacle unit  10  and plug  40  of  FIG. 5A , taken along line  6 C- 6 C. With the plug  40  in alignment with the female electrical fitting  12  of the socket  13 , the plug  40  can be received in the electrical receptacle unit  10  to establish an electrical connection therewith. In  FIG. 6C , the locking bracket  16  remains in the unlocked position so that the plug  40  is not otherwise obstructed and can, thus, be disconnected from the socket  13  with a simple pulling force. With reference to  FIGS. 2, 6C  and  18 A, the locking bracket  16  further includes a pair of positioning arms  21  that extend from the central portion  19  in the same direction as the lock tab  18 . Each positioning arm  21  extends from the central portion  19  at a location that is generally adjacent to, but spaced inwardly from, a respective one of the support arms  17 . As perhaps best seen in  FIG. 6C , the positioning arms  21  are generally L-shaped. Additionally, each positioning arm  21  extends away from the central portion  19  at an angle such that the “corner” of the L-shape is the portion of the positioning arm  21  that is farthest away from a plane defined by the central portion  19  of the locking bracket  16 . 
       FIG. 6D  is a top cross-sectional view of the electrical receptacle unit  10  and plug  40  of  FIG. 6C , shown with the locking bracket  16  being transitioned from the unlocked position to the locked position, and  FIG. 6E  is a top cross-sectional view of the electrical receptacle unit  10  and plug  40  of  FIG. 5B , taken along line  6 E- 6 E. With the plug  40  seated in the socket  13 , the plug  10  can be secured by maneuvering the locking bracket  16  from the unlocked position to the locked position. As can be seen in  FIGS. 6D, 6E and 18A , the plate  14  of the electrical receptacle unit  10  includes two pairs of spaced-apart transverse grooves  27 , 28  disposed along the outwardly-facing surface thereof. More particularly, a pair of transverse grooves  27 , 28  is disposed at each side of the plate  10 , with respective first transverse grooves  27  in alignment with one another and respective second transverse grooves  28  in alignment with one another. 
     When in the unlocked position, the positioning arms  21  of the locking bracket  16  are seated, in an undeflected state, within respective first transverse grooves  27  of the plate, as shown in  FIG. 6C . To transition the locking bracket  16  to the locked position, a pushing force (represented by a first solid arrow in  FIG. 6D ) is applied to the grip tab  23 . This applied force causes the positioning arms  21  of the locking bracket to push against the upwardly inclined portions of the respective first transverse grooves  27 , which, in turn, cause the positioning arms  21  to be deflected toward the plug  40  (as shown by a second solid arrow in  FIG. 6D ). 
     Once the positioning arms  21  have been deflected sufficiently to clear the first transverse grooves  27  of the plate  14 , the applied force causes the locking bracket  16  to shift inwardly toward the plug  40  until the positioning arms  21  reach the second transverse grooves  28 . Here, the positioning arms  21  snap back to the undeflected state with each positioning arm  21  seated within a respective second transverse groove  28  of the plate  14  (as shown by a solid arrow in  FIG. 6E ). As the positioning arms  21  become seated in the second transverse grooves, the inward-facing lock tab  18  of the locking bracket  16  passes over the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 . The lock tab  18  obstructs the plug  40  such that it will not become “unplugged” or otherwise disconnected accidentally from the socket  13 , as can perhaps best be seen in  FIG. 18A . With the positioning arms  21  seated in the second transverse grooves  28  and the lock tab  18  positioned over the ledge  34 , the locking bracket  16  is now arranged in the locked position. 
       FIG. 6F  is a top cross-sectional view of the electrical receptacle unit  10  and plug  40  of  FIG. 6E , shown with the locking bracket  16  being transitioned from the locked position to the unlocked position. As shown in  FIG. 6F , the locking bracket  16  can be returned to the unlocked position in a similar manner. A pulling force (represented by a first solid arrow in  FIG. 6F ) is applied to the grip tab  23 . This applied force causes the positioning arms  21  of the locking bracket to push against the upwardly inclined portions of the respective second transverse grooves  28  (in the opposite direction than before), which, in turn, cause the positioning arms  21  to be deflected toward the plug  40  (as shown by a second solid arrow in  FIG. 6F ). Once the positioning arms  21  have been deflected sufficiently to clear the second transverse grooves  27  of the plate  14 , the applied force causes the locking bracket  16  to shift outwardly away from the plug  40  until the positioning arms  21  reach the first transverse grooves  27 . Here, the positioning arms  21  snap back to the undeflected state with each positioning arm  21  seated within a respective first transverse groove  27  of the plate  14 . With the positioning arms  21  seated in the first transverse grooves  27 , the lock tab  18  no longer obstructs the ledge  34 , and the plug  40  is free to be removed from the socket  13 . 
       FIG. 7  is a front isometric view of another electrical receptacle unit  110  with locking feature in accordance with a preferred embodiment of the present invention. As shown therein, the electrical receptacle unit  110  includes a female electrical fitting  112 , a surrounding socket  113 , and a plate  114  disposed at a front of the surrounding socket  113 . The illustrated female fitting  112  is in the form of a panel-mount C13-type receptacle, but it will be appreciated that various other receptacle types with different electrical connection configurations also exist. In at least some embodiments, the plate  114  is integral with the socket  113 , but, in other embodiments, the plate  114  may be attached during or after manufacturing. Further, in some contemplated embodiments, the plate is integral with, or attached to, the electrical fitting. 
       FIG. 8  is a front isometric view of the electrical receptacle unit  110  of  FIG. 7  shown mounted in a fixture  100 , wherein the fixture  100  is illustrated schematically. The receptacle unit  110  may be mounted in various fixtures using screws, solder joints, or in other known ways; the receptacle (and especially the socket) may include additional features to facilitate such mounting. In accordance with one or more preferred approaches to mounting the receptacle unit  110 , the walls of the socket  113  may include locking tabs  115  (as can be seen in  FIG. 7 ) that are naturally depressed as the socket  113  is maneuvered into position in the fixture  100 , but are biased to spring outward when the socket  113  is fully inserted into such fixture  100 , thereby holding the receptacle unit  110  in place in the fixture  100 . 
     As can be seen in  FIGS. 7, 8 and 18B , the electrical receptacle unit  110  further includes a locking bracket  116 . The locking bracket  116  includes a flattened central portion  119  disposed between a pair of support arms  117 . The support arms  117  extend toward sides of the plate  114  and are secured thereto via hinge pins  129 . In a contemplated embodiment, the hinge pins  129  protrude outwardly away from the plate  114  and through corresponding apertures of the support arms  117 . In this manner, the hinge pins  129  facilitate rotational movement of the locking bracket  116  relative to the plate  114  so that the locking bracket can be transitioned between unlocked and locked positions. 
     In at least some embodiments, the locking bracket  116  is manufactured separately from the electrical receptacle unit  110  and is fastened thereto. It is contemplated that the locking bracket  116  can be pre-installed or can be installed on the receptacle unit  110  after the receptacle unit  110  has been put into use. In this latter regard, the support arms  117  need only be deflected far enough away from one another to be fit at either side of the plate, with the hinge pins  129  received in corresponding apertures of the support arms  117 . It is contemplated that deflection of the support arms  117  can be accomplished with the aid of a flat head screwdriver, which can be used as a lever against one of the support arms  117 . The locking bracket  116  can likewise be uninstalled from the receptacle unit  110  in a similar manner without the receptacle unit  110  needing to be removed or uninstalled. In at least some embodiments, it is contemplated that the locking bracket  116  is made from a durable solid material, such as a hardened thin metal material. 
     The female electrical fitting  112  is adapted to receive a corresponding male electrical fitting. In this regard,  FIG. 9  is a front isometric view of the electrical receptacle unit  110  of  FIG. 7 , shown with an unconnected power cord. The power cord includes a plug  40  attached to the end of an electrical cable  44 . The plug  40  includes a male fitting  42 , from which male electrical contacts extend as well as a socket  43  surrounding the male electrical contacts. A ledge  34  is formed at the junction of the male fitting  42  and the socket  43 , where trailing edges of the socket  43  extend beyond leading edges of the male fitting  42  (as the plug  40  is received in the receptacle unit  110 ). In at least some embodiments, the plug  40  is of conventional construction, as is the electrical cable  44  to which it is attached. 
     The plug  40  may be inserted into the receptacle unit  110  such that a conventional electrical connection is established and maintained. In this regard,  FIG. 10A  is a front isometric view of the electrical receptacle unit  110  of  FIG. 7 , shown with a power cord connected thereto in an unlocked position, and  FIG. 10B  is a front isometric view of the electrical receptacle unit  110  of  FIG. 7 , shown with the power cord connected thereto in a locked position. When fully seated in the socket  113 , the plug  40  can be retained by pivoting the locking bracket  116  toward the plate  114  so that a lock tab  118  rests over the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 . In so doing, the lock tab  118  obstructs the plug  40  such that it will not become “unplugged” or otherwise disconnected accidentally from the socket  113 , thereby effectively locking the plug  40  into position. In a contemplated embodiment, the lock tab  118  extends, at an angle, from an inward-facing edge of the central portion  119  of the locking bracket  116  (as perhaps best seen in  FIG. 11D ). 
       FIGS. 11A-11D  are a series of top views of the electrical receptacle unit  110  and plug  40  of  FIGS. 9, 10A and 10B  that illustrate locking and unlocking the locking bracket  116  relative to the plug  40 . In  FIGS. 11A-11D , solid arrows are sometimes used to illustrate movement of various components of the locking bracket  116 . 
       FIG. 11A  is a top view of the electrical receptacle unit  110  and plug  40  of  FIG. 9 . In  FIG. 11A , the locking bracket  116  is arranged in the unlocked position so that the plug  40  can be received in the socket  113  of the electrical receptacle unit  110 . With additional reference to  FIGS. 9 and 18B , distal ends of the support arms  117  are anchored to, and received within, notched areas  126  along opposed lateral edges of the plate  114 . As the locking bracket  116  is pivoted about the hinge pins  129 , distal ends of the support arms  117  remain within the notched areas  126 , thereby assisting with keeping the locking bracket  116  aligned relative to the receptacle unit  110 . 
     As further shown in  FIG. 11A , the locking bracket  116  includes a grip tab  123  that extends outwardly and upwardly from a side of the central portion  119 , opposite from the lock tab  118 . The grip tab  123  provides a surface by which the locking bracket  116  can be grasped and maneuvered by a user, such as by holding the grip tab  123  between the user&#39;s thumb and forefinger. In this manner, the grip tab  123  facilitates a user having the ability to transition the locking bracket  116  manually between the unlocked and locked positions. 
       FIG. 11B  is a top view of the electrical receptacle unit  110  and plug  40  of  FIG. 10A . With the plug  40  in alignment with the female electrical fitting  112  of the socket  113 , the plug  40  can be received in the electrical receptacle unit  110  to establish an electrical connection therewith. In  FIG. 11B , the locking bracket  116  remains in the unlocked position so that the plug  40  is not otherwise obstructed and can, thus, be disconnected from the socket  113  with a simple pulling force. To transition the locking bracket  116  from the unlocked position to the locked position, a rotational force is applied to the grip tab  123 . This applied force causes the locking bracket  116  to pivot, about the hinge pins  129 , toward the plug  40 . The direction of rotation is represented by a solid arrow in  FIG. 11B . 
       FIG. 11C  is a top view of the electrical receptacle unit  110  and plug  40  of  FIG. 10B ; and  FIG. 11D  is a top cross-sectional view of the electrical receptacle unit  110  and plug  40  of  FIG. 10B , taken along line  11 D- 11 D. The lock tab  118  of the locking bracket  116  is pivoted toward the plug  40  until the lock tab  118  passes over the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 . Once the lock tab  118  is positioned over the top of the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 , the locking bracket  116  is in the locked position. As perhaps best seen in  FIGS. 11D and 18B , the lock tab  118  obstructs the plug  40  such that it will not become “unplugged” or otherwise disconnected accidentally from the socket  113 . Additionally, the hinge pins  129 , which provide a pivot point for the locking bracket  116 , are positioned such that a pulling force applied to the plug  40  does not cause the lock tab  118  to become disengaged. The locking bracket  116  can be transitioned from the locked position back to the unlocked position by pivoting the locking bracket  116  away from the plug  40  so that the lock tab  118  no longer obstructs the ledge  34 . 
       FIG. 12A  is a front isometric view of another electrical receptacle unit  210  with locking feature in accordance with a preferred embodiment of the present invention, and  FIG. 12B  is a front view of the electrical receptacle unit of  FIG. 12A . The electrical receptacle unit  210  depicted in  FIGS. 12A and 12B  is similar in at least some respects to the electrical receptacle unit  110  depicted in  FIGS. 7-11D . As discussed in greater detail below, the electrical receptacle unit  210  of  FIGS. 12A and 12B  includes a spring-biased locking bracket  216  that enhances locking functionality of the unit. 
     As shown in  FIGS. 12A and 12B , the electrical receptacle unit  210  includes a female electrical fitting  212 , a surrounding socket  213 , and a plate  214  disposed at a front of the surrounding socket  213 . The illustrated female fitting  212  is in the form of a panel-mount C13-type receptacle, but it will be appreciated that various other receptacle types with different electrical connection configurations also exist. In at least some embodiments, the plate  214  is integral with the socket  213 , but, in other embodiments, the plate  214  may be attached during or after manufacturing. Further, in some contemplated embodiments, the plate is integral with, or attached to, the electrical fitting. 
       FIG. 13  is a front isometric view of the electrical receptacle unit  210  of  FIG. 12A  shown mounted in a fixture  200 , wherein the fixture  200  is illustrated schematically. The receptacle unit  210  may be mounted in various fixtures using screws, solder joints, or in other known ways; the receptacle (and especially the socket) may include additional features to facilitate such mounting. In accordance with one or more preferred approaches to mounting the receptacle unit  210 , the walls of the socket  213  may include locking tabs  215  (as can be seen in  FIG. 12A ) that are naturally depressed as the socket  213  is maneuvered into position in the fixture  200 , but are biased to spring outward when the socket  213  is fully inserted into such fixture  200 , thereby holding the receptacle unit  210  in place in the fixture  200 . 
     As can be seen in  FIGS. 12A, 12B and 13 , the electrical receptacle unit  210  further includes a spring-biased locking bracket  216 . The spring-biased locking bracket  216  includes a flattened central portion  219  disposed between a pair of support arms  217 . The support arms  217  extend toward sides of the plate  214  and are secured thereto via hinge pins  229 . In a contemplated embodiment, the hinge pins  229  protrude outwardly away from the plate  214  and through corresponding apertures of the support arms  217 . In this manner, the hinge pins  229  facilitate rotational movement of the spring-biased locking bracket  216  relative to the plate  214  so that the locking bracket can be maneuvered into and out of the locked position. 
     Each support arm  217  is further anchored to the plate via a spring  233  that biases the locking bracket  216  toward a locked position, whereby the spring-biased locking bracket  214  helps to secure, or lock, a plug that is received in the electrical receptacle unit  210 . Each support arm  217  includes an angled tab  237  that extends inwardly adjacent to the spring  233  and a protrusion  235  that extends inwardly in generally the same direction as the angled tab  237 . The tabs  237  shield the springs  233  from other structures and help to align the spring-biased locking bracket  216  against the plate  214  when the locking bracket is in the locked position. The inwardly-oriented protrusions  235  facilitate the spring-biased locking bracket  216  being snap-fit in the locked position, as will be explained in greater detail below. 
     In at least some embodiments, the locking bracket  216  is manufactured separately from the electrical receptacle unit  210  and is fastened thereto. It is contemplated that the spring-biased locking bracket  216  can be pre-installed or can be installed on the receptacle unit  210  after the receptacle unit  210  has been put into use. In this latter regard, the support arms  217  need only be deflected far enough away from one another to be fit at either side of the plate  214 , with the hinge pins  229  received in corresponding apertures of the support arms  217 . It is contemplated that deflection of the support arms  217  can be accomplished with the aid of a flat head screwdriver, which can be used as a lever against one of the support arms  217 . The spring-biased locking bracket  216  can likewise be uninstalled from the receptacle unit  210  in a similar manner without the receptacle unit  210  needing to be removed or uninstalled. In at least some embodiments, it is contemplated that the spring-biased locking bracket  216  is made from a durable solid material, such as a hardened thin metal material. 
     The female electrical fitting  212  is adapted to receive a corresponding male electrical fitting. In this regard,  FIG. 14  is a front isometric view of the electrical receptacle unit  210  of  FIG. 12A , shown with an unconnected power cord. The power cord includes a plug  40  attached to the end of an electrical cable  44 . The plug  40  includes a male fitting  42 , from which male electrical contacts extend as well as a socket  43  surrounding the male electrical contacts. A ledge  34  is formed at the junction of the male fitting  42  and the socket  43 , where trailing edges of the socket  43  extend beyond leading edges of the male fitting  42  (as the plug  40  is received in the receptacle unit  210 ). In at least some embodiments, the plug  40  is of conventional construction, as is the electrical cable  44  to which it is attached. 
     The plug  40  may be inserted into the receptacle unit  210  such that a conventional electrical connection is established and maintained. In this regard,  FIG. 15A  is a front isometric view of the electrical receptacle unit  210  of  FIG. 12A , shown with a power cord connected thereto, and  FIG. 15B  is a front isometric view of the electrical receptacle unit  210  of  FIG. 12A , shown with the power cord connected thereto in a locked position. Because the spring-biased locking bracket  216  is biased toward the locked position, the locking bracket  216  should be pivoted away from the socket  213 , against the bias of the spring  233 , so as not to obstruct the plug  40  during insertion into the receptacle unit  210 . Once fully seated in the socket  213 , the plug  40  can be secured within the socket  213  by the spring-biased locking bracket  216 . When in the locked position, the spring-biased locking bracket  216  is seated against the plate  214 , and a lock tab  218  rests over the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 . In so doing, the lock tab  218  obstructs the plug  40  such that it will not become “unplugged” or otherwise disconnected accidentally from the socket  213 , thereby effectively locking the plug  40  into position. In a contemplated embodiment, the lock tab  218  extends, at an angle, from an inward-facing edge of the central portion  219  of the locking bracket  216  (as perhaps best seen in  FIG. 16D ). 
       FIGS. 16A-16D  are a series of top views of the electrical receptacle unit  210  and plug  40  of  FIGS. 14, 15A and 15B  that illustrate locking and unlocking the spring-biased locking bracket  216  relative to the plug  40 . In  FIGS. 16A-16D , solid arrows are sometimes used to illustrate movement of various components of the locking bracket  216 . 
       FIG. 16A  is a top view of the electrical receptacle unit  210  and plug  40  of  FIG. 14 . In  FIG. 16A , the spring-biased locking bracket  216  has been pivoted away from the socket  213 , against the bias of the springs  233 , so that the plug  40  can be received in the socket  213 . With additional reference to  FIGS. 12B and 14 , distal ends of the support arms  217  are anchored to, and received within, notched areas  226  along opposed lateral edges of the plate  214 . As the spring-biased locking bracket  216  is pivoted about the hinge pins  229 , distal ends of the support arms  217  remain within the notched areas  226 , thereby assisting with keeping the locking bracket  216  aligned relative to the receptacle unit  210 . As shown in  FIGS. 14 and 16A , each notched area  226  of the plate  214  includes a cavity  251 , which is sized and shaped to receive a respective protrusion  235  of the support arms  217  when the locking bracket  216  is in the locked position. 
     As further shown in  FIGS. 14 and 16A , the locking bracket  216  includes a grip tab  223  that extends outwardly and upwardly from a side of the central portion  219 , opposite from the lock tab  218 . The grip tab  223  provides a surface by which the spring-biased locking bracket  216  can be grasped and maneuvered by a user. For example, as the plug  40  is inserted into the receptacle unit  210 , a user can apply a force against the grip tab  223  in order to maneuver the spring-biased locking bracket  216  out of the way (i.e., by pivoting the spring-biased locking bracket against the bias of the springs  233 ) to provide an unobstructed path to the plug  40 . 
       FIG. 16B  is a top view of the electrical receptacle unit  210  and plug  40  of  FIG. 15A , and  FIG. 16C  is a top view of the electrical receptacle unit  210  and plug  40  of  FIG. 15B . With the plug  40  in alignment with the female electrical fitting  212  of the socket  213  and the spring-biased locking bracket  216  maneuvered out of the way, the plug  40  can be received in the electrical receptacle unit  210  to establish an electrical connection therewith. Once properly seated, the grip tab  223  can be released by the user, thereby permitting the spring-biased locking bracket to pivot, about the hinge pins  229 , toward the locked position. The direction of rotation is represented by a solid arrow in  FIG. 16B . 
     In at least some embodiments, it is contemplated that the bias of the springs  233  is sufficient to cause the locking bracket  216  to return fully to the locked position upon release of the grip tab  223 . When in the locked position, the lock tab  218  physically obstructs the plug  40  from being removed from the socket  213  and the inwardly-oriented protrusions  235  of the support arms are received in respective cavities  251  of the plate  214 . In other contemplated embodiments, a slight external force, applied against the grip tab  223 , may be necessary to cause the support arms  217  to be deflected outwardly by a sufficient margin such that the protrusions  235  can be received within the respective cavities  251  of the plate  214 . In either case, it is contemplated that the protrusions  235  (perhaps best seen in  FIG. 12B ) are received within the respective cavities  251  of the plate  214  via snap-fit. In this manner, the protrusions  235  further encourage the spring-biased locking bracket  214  to remain in the locked position. 
       FIG. 16D  is a top cross-sectional view of the electrical receptacle unit  210  and plug  40  of  FIG. 15B , taken along line  16 D- 16 D. In  FIG. 16D , the spring-biased locking bracket  216  is shown in the locked position. Here, the lock tab  218  is positioned over the ledge  34  formed at the junction of the male fitting  42  and the plug socket  43 , and the inwardly-oriented protrusions  235  are received within the cavities  251  of the plate  214 . In the locked position, the lock tab  218  obstructs the plug  40  such that it will not become “unplugged” or otherwise disconnected accidentally from the socket  213 . Additionally, with the protrusions  235  of the spring-biased locking bracket  216  seated within respective cavities  251  of the plate  214 , the locking bracket is further encouraged to remain in the locked position. The hinge pins  229 , which provide a pivot point for the locking bracket  216 , are positioned such that a pulling force applied to the plug  40  does not cause the lock tab  218  to become disengaged. 
     It is contemplated that the spring-biased locking bracket  216  can be unlocked by applying a force against the grip tab  223  to unseat the protrusions  235  from the cavities  251  and then pivot the locking bracket  216  away from the plug  40  against the bias of the springs  233 . In so doing, the lock tab  218  no longer obstructs the ledge  34 , and the plug  40  is free to be removed from the socket  213 . 
     With respect to each of the embodiments described hereinabove, installation of the locking bracket  16 , 116 , 216  does not have a significant impact on the overall height of the receptacle unit  10 , 110 , 210 , even when the locking bracket  16 , 116 , 216  is in the unlocked position. In this regard,  FIG. 17A  is a top view of the electrical receptacle unit  10  and plug  40  of  FIG. 5A , illustrating a height H 1  of the locking bracket  16  in the unlocked position, and  FIG. 17B  is a top view of the electrical receptacle unit  110  and plug  40  of  FIG. 10A , illustrating a height  112  of the locking bracket  116  in the unlocked position. As shown in  FIGS. 17A and 17B , the locking bracket  16 , 116  extends only a modest distance  111 , 112  above the top of the receptacle unit  10 , 110  in the unlocked position. As a result, the locking bracket  16 , 116  is less likely to interfere with other structures, including adjacent receptacle units or a surrounding enclosure. 
     With respect to each of the embodiments described hereinabove, dimensions of the locking brackets  16 , 116 , 216  are such that the overall footprint of the receptacle units  10 , 110 , 210  in the stacking direction is not affected by installation of the locking brackets  16 , 116 , 216 . In this regard,  FIG. 18A  is an end view of the electrical receptacle unit  10  and plug  40  of  FIG. 5B , illustrating a footprint F 1  of the locking bracket  16  in the stacking direction, and  FIG. 18B  is an end view of the electrical receptacle unit  110  and plug  40  of  FIG. 10B , illustrating a footprint F 2  of the locking bracket  116  in the stacking direction. The stacking direction refers to the direction that receptacle units “stack” along the length of a PDU. As shown in  FIGS. 18A and 18B , installation of the locking bracket  16 , 116  does not expand the overall footprint F 1 ,F 2  of the receptacle unit  10 , 110 . Support arms  17 , 117  engage at sides of the plate  14 , 114  within notched areas  26 , 126  so that the full length of the locking bracket  16 , 116  can be accommodated within the footprint of the receptacle unit  10 , 110  in the stacking direction. Furthermore, in the case of the receptacle unit of  FIG. 18A , it is contemplated that the length of the plate  14  in the stacking direction can be slightly less at the portion that accommodates the locking bracket  16  than at the opposite end. In either embodiment, the ability to fit the locking bracket  16 , 116  to the receptacle unit  10 , 110  without expanding the footprint F 1 , F 2  allows for more receptacle units to be populated per length of PDU. 
     Based on the foregoing information, it will be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those specifically described herein, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing descriptions thereof, without departing from the substance or scope of the present invention. 
     Accordingly, while the present invention has been described herein in detail in relation to one or more preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purpose of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended to be construed to limit the present invention or otherwise exclude any such other embodiments, adaptations, variations, modifications or equivalent arrangements; the present invention being limited only by the claims appended hereto and the equivalents thereof.