Patent Publication Number: US-7905749-B2

Title: Ganged electrical outlets, apparatus, and methods of use

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a divisional application of U.S. patent application Ser. No. 11/355,511, filed Feb. 15, 2006, which claims the benefit of U.S. Provisional Patent Application No. 60/653,577, filed Feb. 15, 2005. These applications are incorporated herein by reference. This divisional application also claims the benefit of U.S. Provisional Patent Application No. 60/758,394, filed Jan. 11, 2006. 
    
    
     FIELD 
     This disclosure pertains to devices for distributing access to electrical power over multiple “outlets” and apparatus and methods of use. Particular aspects of this disclosure pertain to ganged-outlet devices and modules, some of which are configured to be integrated with one or more other ganged-outlet devices in a power-distribution or other unit useable for distributing electrical power to separate electrical equipment units. 
     BACKGROUND 
     A conventional power-distribution unit (PDU) is an assembly of multiple electrical “outlets” (also called “receptacles”) that receive electrical power from a source and distribute the electrical power via the outlets to one or more separate electronic equipment units having respective power cords plugged into respective outlets of the PDU. PDUs can be used in any of various applications and settings such as, for example, in or on a rack used for housing and supporting various pieces of electronic equipment. 
     Certain types of PDUs support remote control of one or more of their respective outlets. This remote control can be accomplished by, for example, by a remote computer communicating through a network with the PDU. Examples of remotely controllable PDUs include products made and distributed by Server Technology, Inc., of Reno, Nev. 
     One such prior art Server Technology product is the Sentry CDU™ PDU system  100 , shown in  FIGS. 1A and 1B . The SENTRY CDU PDU includes multiple ganged-outlet modules  102 , with each ganged-outlet module having multiple receptacles (outlets)  104  such as IEC C13 receptacles. Each ganged-outlet module  102  includes seven receptacles  104  arranged linearly in a ganged-outlet housing  106  mounted vertically in the PDU system  100  as shown in the FIGS. Each receptacle  104  includes a female ground socket  108 , a female neutral socket  110 , and a female line (“hot”) socket  112 . As shown in  FIG. 1B , in each ganged-outlet housing  106 , all ground sockets  108  are interconnected by a common linear ground rail  114 ; all neutral sockets  110  are interconnected by a common linear neutral rail  116  parallel to the ground rail  114 , and all line sockets  112  are interconnected by common linear line rail  118  also parallel to the ground rail  114 . Accordingly, corresponding sockets of adjacent outlets of each ganged-outlet module share a common rail and are not individually controllable. 
     As shown in  FIGS. 1A and 1B , the power rails  114 ,  116 ,  118  are external to the respective housings  106 . As a result of their external placement, in certain environments, the power rails are exposed to other structure in the vicinity of the power rails. In some applications, the power rails may be vulnerable to unintentional contact with and/or disruption by other components inside the PDU system  100 . Whenever multiple ganged-outlet modules  102  are mounted in a housing  120 , such as shown in  FIGS. 1A-1B , the exposed power rails  114 ,  116 ,  118  typically are separated electrically from other components within the housing  120  by means of flexible insulative polymeric sheeting. Thus, in certain embodiments of this type of PDU system  100 , the exposed power rails  114 ,  116 ,  118  require use of extra insulating material within the PDU system  100 . In such embodiments, mis-assembly of the PDU system  100  at time of manufacture or incorrect re-assembly after making a repair to the PDU system  100  may present a risk of electrical shorts. 
     In addition, the ganged-outlet modules  102  of  FIGS. 1A and 1B  accommodate only conventional two- or three-pronged connectors such as the IEC C13 receptacles  104  shown. As a result, these types of prior art receptacles typically do not accommodate other types of connectors, such as NEMA connectors. 
     One conventional PDU system  230  having NEMA compatible receptacles is a Server Technology PDU-VL16™ system, as shown in  FIG. 2 . In the PDU-VL16 system  230 , the NEMA compatible receptacles  232  are not ganged, but rather are mounted and manually wired individually in the PDU housing  234 . In this conventional PDU system  230 , each individual NEMA receptacle  232  is separately wired to each of three power-supply lines (ground, neutral, and line) inside the housing  234 . Separately manually wiring each receptacle  232  can present a number of disadvantages. For example, it can make assembly of the PDU system  230  time-consuming, and thus expensive, expensive to assemble. Separately manually wiring each receptacle  232  can also make such PDU systems  230  less reliable. Also, substantial space must typically be provided inside the housing  234  for each of the receptacles  232 , their mounting structures, and their respective wiring. 
     SUMMARY 
     The present invention provides, inter alia, a ganged electrical outlet device. Each ganged electrical outlet device can comprise a plurality of interconnected, or ganged, electrical outlets. In one exemplary implementation, each outlet includes a hot socket, neutral socket and ground socket to receive respective hot prongs, neutral prongs and ground prongs of an electrical device power cord. The plurality of power outlets are interconnected by at least one common power rail, line, wire, or other electrical connecting element. In some implementations, the at least one common power rail comprises (i) a first neutral power rail electrically coupled to the neutral sockets of each of the plurality of outlets; and (ii) a second ground power rail electrically coupled to the ground sockets of each of the plurality of outlets. The first neutral power rail and the second ground power rail are configured to transmit a neutral component of a power source to the neutral sockets and a ground component of a power source to the ground sockets, respectively, of each of the plurality of power outlets. 
     In one exemplary implementation, a separate, dedicated control power line is electrically coupled to the hot socket of each of the plurality of power outlets. Each dedicated control power line can be selectively controllable to allow or prevent transmission of a hot component of a power source to a respective hot socket of one of the plurality of outlets. In other words, the transmission of the hot component of a power source to any one of the outlets can be controlled independent and irrespective of any other of the power outlets. In this manner, power to one of the plurality of outlets can be shut-off, while, for example, power to an adjacent outlet can be turned-on and vice versa. In another example, power to outlets being occupied by a plug of an electrical device requiring power can be turned-on while outlets not occupied by a plug can be turned-off. As can be recognized, a user of the disclosed ganged electrical outlet device can configure the outlets in a variety of ways for a variety of applications. 
     In some implementations, first ends of the dedicated control power lines are electrically connected to the respective hot sockets of the plurality of outlets and second ends of the dedicated control power lines are electrically connected to a separate connection on a printed circuit board. Each connection can be electrically coupled to a separate circuit on or in the circuit board, with each circuit being coupled to a power regulating device, such as an intelligent power module. The power regulating device acts as a gate to allow, prevent or otherwise control, transmission of the hot component of a power source to a respective outlet. 
     In specific exemplary embodiments, the ganged-outlet device comprises a plurality of power outlets mounted within a ganged-outlet housing. The least one common power rail interconnecting the plurality of outlets can be disposed within the housing with one end of each of the at least one common power rail disposed external to the housing. The external end can be electrically coupled to the printed circuit board such that a neutral and/or ground component of a power source can be transmitted to the outlets via the at least one common power rail. The second ends of each of the separate, dedicated control power lines can extend external to the housing and be electrically coupled to the printed circuit board to allow electrical interconnectivity between the hot sockets of the outlets and the respective power regulating devices mounted to the printed circuit board. 
     In other exemplary embodiments, the ganged electrical outlet device comprises a plurality of power outlet housings with each power outlet housing containing one of the plurality of power outlets. The plurality of power outlets are interconnected by at least one power rail extending from outlet housing to outlet housing. In some embodiments, the power outlet housings can be interconnected by a plurality of common, parallel power rails. In some embodiments, one end of the at least one power rail can be electrically connected to the printed circuit board to facilitate transmission of a neutral or ground component from a power source to the outlets via the printed circuit board. Each housing can have a respective separate, dedicated hot component power control line extending therefrom that is electrically connected to a separate circuit on or in the printed circuit board. In some embodiments, each circuit is electrically connected to and controlled by a separate power module, which can activate one or more relays to turn the respective control lines to one or more outlets on and off irrespective of the other outlets. 
     In some embodiments, the ganged-outlet housing or the power outlet housings can penetrate at least one power outlet passage in an electrical equipment unit. The electrical equipment housing may provide a power distribution unit and, in certain applications, may be mounted within an electrical equipment rack. 
     In some embodiments, one or more of the outlets may include a NEMA 5-20R compatible power outlet. In some embodiments, one or more of NEMA 5-20R compatible power outlets are compatible with standard three-prong and two-prong electrical power cords for supplying AC power. In some embodiments, one or more of the plurality of electrical power outlets can comprise an IEC compatible outlet. 
     Use of power rails located inside a ganged-outlet housing or extending between electrical outlet housings can reduce exposure of electrical conductors. Furthermore, the ganged-outlet housing or providing multiple outlet housings can provide insulation between the power rails and lines, and other electrical components within an electrical equipment unit. 
     In certain embodiments employing the ganged-outlet housing or the multiple outlet housings, the housing or housings can be made from a rigid insulating material. Desirably, the ganged-outlet housing or each of the multiple outlet housings can include a front portion and a rear portion, wherein the rear portion can be extended through a passage in the housing of a power-distribution unit or other apparatus until stopped by the front portion. The ganged-outlet housing or each of the multiple outlet housings can include resilient mounting prongs for securing the housing or housings to the apparatus housing. 
     In some embodiments, the ganged-outlet device may be fused. 
     It is to be understood that the foregoing is a brief summary of some aspects of this disclosure or various embodiments. The scope of the present disclosure therefore is not determined by whether any embodiment includes all features or advantages noted above or addresses all issues or deficiencies in the prior art noted above. 
     In addition, there are additional aspects of the present disclosure. They will become apparent as the specification proceeds. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The preferred and other embodiments are shown in the attached drawings in which: 
         FIG. 1A  is a plan view of the front surface of an exemplary embodiment of a power-distribution unit (PDU) comprising multiple ganged-outlet modules; 
         FIG. 1B  is a plan view, from behind, of the front surface of the embodiment shown in  FIG. 1A , revealing details of power rails interconnecting the outlets together in each ganged-outlet module; 
         FIG. 2  is an elevational perspective view of a conventional PDU system including multiple individual outlets; 
         FIG. 3  is a side elevational view of an exemplary embodiment of a ganged-outlet device having multiple NEMA 5-20R outlets; 
         FIG. 4  is a plan view of the rear surface of the embodiment shown in  FIG. 3 ; 
         FIG. 5  is a plan view of the front surface of the embodiment shown in  FIG. 3 ; 
         FIGS. 6A-6C  present orthogonal views of an exemplary power rail used in the embodiment of  FIG. 3 ; 
         FIG. 7  is a first-end view of the embodiment shown in  FIG. 3 ; 
         FIG. 8  is a second-end view of the embodiment of  FIG. 3 ; 
         FIG. 9  is an elevational perspective view of a PDU apparatus with multiple ganged-outlet devices having multiple outlet housing with each housing providing a power outlet, and shown with a portion of the apparatus housing removed; 
         FIG. 10  is a fragmentary perspective view of the PDU apparatus of  FIG. 9 ; 
         FIG. 11  is a perspective view of an outlet housing exemplary of the outlet housings shown in  FIG. 10 ; 
         FIG. 12  is a top view of the outlet housing of  FIG. 11  shown with an end cap removed. 
         FIG. 13  is a cross-sectional side view of the outlet housing of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
     The various representative embodiments described below are exemplary and are not intended to be limiting in any way. 
     A first representative embodiment of a ganged-outlet, or ganged-outlet module,  310  is shown in  FIG. 3 . As used herein, the term “ganged-outlet” or “ganged-outlet module” means a plurality of outlets, or receptacles, pre-arranged in a fixed orientation with respect to each other, and thereby being mountable as a unit in another structure. In the preferred embodiment, the ganged-outlet is mounted in a PDU housing. Ganged-outlet module  310  includes multiple electrical outlets contained within or assembled together with respect to a single housing. The ganged-outlet module  310  can be mounted in or to another housing (e.g., a housing of a power-distribution unit, or “PDU system”) configured to contain multiple modules. 
     As shown in  FIG. 3 , the ganged-outlet module  310  of this embodiment includes four outlets ( 456 ,  458 ,  460 ,  462 , shown in  FIG. 5 ) each of NEMA 5-20R type, contained in a housing  311 . It will be understood that this embodiment, and other embodiments described herein as having NEMA 5-20R type outlets, are exemplary only and that any of various other types of outlets alternatively can be used. For example, the “outlets” can be other NEMA types (e.g., NEMA 5-15R, NEMA 6-20R, NEMA 6-30R or NEMA 6-50R) or any of various EC types (e.g., IEC C13). It also will be understood that all the “outlets” in a particular ganged-outlet module  310 , or other ganged-outlet described herein, need not be identical. It also will be understood that the “outlets” are not limited to three-prong receptacles; alternatively, one or more of the “outlets” can be configured for two or more than three prongs in the mating male connector. It also will be understood that the “outlets” are not limited to having female prong receptacles. In any “outlet,” one or more of the “prong receptacles” can be male instead of female connection elements, as conditions or needs indicate. In general, as used herein, female and male “prong receptacles” are termed “power-connection elements.” 
     The housing  311  includes a front portion  312  and a rear portion  314 . The front portion  312  is substantially planar, and the rear portion  314  is substantially planar and parallel to the front portion  312 . The housing  311  also includes longitudinally extending side portions  316  (one of which is viewable in  FIG. 3 ) and transverse end portions  318 ,  320 . The front portion  312 , rear portion  314 , side portions  316 , and end portions  318 ,  320  are generally orthogonal to each other. The front and rear portions  312 ,  314  can be made of any suitable, typically rigid, material, most desirably of a rigid polymeric (“plastic”) material. In at least certain embodiments, the front and rear portions  312 ,  314  are made from an electrically insulative material. The side portions  316  and the end portions  318 ,  320  may be integrally formed, optionally along with the front portion  312  or the rear portion  314 . Alternatively, fewer portions of the housing  311  may be integrally formed, and each may be a separate piece, if desired. 
     The front portion  312  desirably is slightly wider and longer than the rear portion  314  so as to form a shoulder  322 ,  324 ,  326  about the perimeter of the front portion  312 . The shoulder  322 ,  324 ,  326  may be used for mounting the housing  311  to a housing of a PDU system (not shown). 
     In the depicted embodiment, the side portions  316  and end portions  318 ,  320  each include one or more respective outwardly projecting, resilient prongs or locking tabs, e.g.,  328 ,  330 ,  332 ,  334 . Each resilient prong  328 ,  330 ,  332 ,  334  may be integrally formed in a respective surface of the side portions  316  and/or end portions  318 ,  320 , such as by incorporation into a mold for the side and/or end portions. For example, each resilient prong  328 ,  330 ,  332 ,  334  may be a cantilevered tab, the end of the tab having an outward pointing wedge, formed by gaps between the tab and its surrounding structure on at least a portion of three sides of the tab. Alternatively, the resilient prongs  328 ,  330 ,  332 ,  334  can be separate devices attached to the housing  311 . Each resilient prong  328 ,  330 ,  332 ,  334  is configured to be depressed inwardly (toward the interior of the housing  311 ). 
     The resilient prongs  328 ,  330 ,  332 ,  334  may used to facilitate mounting the housing  311  to a housing of a PDU system. Specifically, the front portion of a PDU-system housing (not shown) may be provided with a cutout having dimensions conforming to, but slightly longer and wider than, the rear portion  314  and slightly shorter and narrower than of the front portion  312  (including its shoulder portions  322 ,  324 ,  326 ). Thus, the housing  311  is slidably inserted (rear portion  314  first) into the cutout until stopped by the shoulder  322 ,  324 ,  326 . Meanwhile, as the prongs  328 ,  330 ,  332 ,  334  engage the edge of the cutout, they are depressed inwardly until insertion progresses past the apices of the prongs  328 ,  330 ,  332 ,  334 , at which time the prongs  328 ,  330 ,  332 ,  334  relax outwardly against the edges of the cutout. When the housing  311  is fully inserted such that the shoulder  322 ,  324 ,  326  is in contact with the surface of the front panel of the PDU-system housing, the prongs  322 ,  330 ,  332 ,  334  are at their respective fully outwardly biased positions as shown in  FIG. 3 , which firmly engage the prongs against the respective edges of the cutout and firmly seats the shoulder  322 ,  324 ,  326  against and to the front pane of the PDU-system housing. To remove the module  310  from the PDU-system housing, the prongs  328 ,  330 ,  332 ,  334  are urged inwardly (toward the interior of the housing  311 ) sufficiently to allow the prongs  328 ,  330 ,  332 ,  334  (as the housing  311  is pulled away from the cutout) to clear the respective edges of the cutout. 
     It will be understood that the depicted number and arrangement of the prongs  322 ,  330 ,  332 ,  334  are exemplary only and are not intended to be limiting. In alternative embodiments, more or fewer prongs may be appropriate, and it may not be necessary to include at least one prong on each surface  316 ,  318 ,  320 . For example, in some applications, the end surfaces  318 ,  320  may not have respective prongs  328 ,  334 . Furthermore, it will be understood that any of various other attachment schemes alternatively can be employed, instead of the prongs  322 ,  330 ,  332 ,  334 , for mounting the housing  311  to a housing of a PDU system or other device incorporating the ganged-outlet module  310 . For example, any of various mounting brackets and clamps could be used. 
     The ganged-outlet module  310  includes a plurality of electrically conductive connection terminals, or connectors,  336 ,  338 ,  340 ,  342 ,  344 ,  346  for making respective electrical connections. The connection terminals  336 ,  338 ,  340 ,  342 ,  344 ,  346  extend rearwardly from (and desirably normal to) the rear portion  314  of the housing  311 . The connection terminals  336 ,  338 ,  340 ,  342 , are used for making respective line connections to respective outlets  456 ,  458 ,  460 ,  462  ( FIG. 5 ), and are linearly arrayed vertically from the upper end  352  of the housing  311  to the lower end  354 . The connection terminals  336 ,  344 ,  346  are linearly arrayed horizontally near the upper end  352  of the housing  311 . The connection terminal  336  is used for making a respective line connection to the outlet  456 , and the connection terminals  344  and  346  are used for making parallel ground and neutral connections, respectively, to all the outlets  456 ,  458 ,  460 ,  462  of the ganged-outlet module  310 . 
     Each of the outlets  456 ,  458 ,  460 ,  462  in the depicted embodiment has a separate respective line-connection terminal  336 ,  338 ,  340 ,  342  to allow independent control (e.g., switching) of power supplied to the respective outlet. By way of example, a respective on-off switch (not shown in  FIG. 4  or  5 ) can be electrically interposed between each of the line-connection terminals  336 ,  338 ,  340 ,  342  and a source of line power. The switches can be manually or electronically actuated, for example. As an example of the latter, the switches can be configured electromechanically such as respective relays, or configured entirely electronically such as respective switching transistor circuits. 
     As an alternative to the depicted embodiment, groups of two or more outlets (e.g., a first group consisting of outlets  456 ,  458  and a second group consisting of outlets  460 ,  462 ) can have their own respective line-connection terminals. Thus, in accordance with this example, a single line-connection terminal can be used to turn on and off both outlets  456 ,  458 , and a single line-connection terminal can be used to turn on and off both outlets  460 ,  462 . Other groupings of outlets are, of course, possible in accordance with the particular setting or conditions in which the ganged-outlets are to be used. For example, a single line-connection terminal could be used turn on and off all of the outlets in a particular ganged-outlet. 
     A respective wire-mounting orifice  348  is defined near the respective distal end  350  of each connection terminal  336 ,  338 ,  340 ,  342 ,  344 ,  346 . The wire-mounting orifice  348  facilitates secure attachment of the respective wire (not shown) supplying power to each particular connection terminal. For example, the respective wire can be connected to each connection terminal by first inserting the free end of the wire through the respective orifice  348  and then wrapping the free end around the respective connection terminal, followed by soldering the resulting connection. It will be understood that other methods of making wire connections alternatively can be used. 
     As a first example, the ends of the line wires, ground wire, and neutral wire can be fitted with female spade lugs adapted to slip onto the respective connection terminals  336 ,  338 ,  340 ,  342 ,  344 ,  346  (which are shown as having a male spade-connector configuration). In some implementations, the female spade lugs can be mounted to a printed circuit board (not shown) and electrically coupled to circuitry on or in the printed circuit board. In a second example, the connection terminals  336 ,  338 ,  340 ,  342 ,  344 ,  346  can be configured with any of various female configurations adapted to accept corresponding male connector terminals fitted to the wire ends. In a third example, the connection terminals  336 ,  338 ,  340 ,  342 ,  344 ,  346  can be provided with connector screws configured for making respective screw connections with the respective wire ends. It will be understood that any of various other connector schemes known in the art alternatively can be used. 
     As noted above, the depicted embodiment includes connection terminals (e.g., item  336 ). It will be understood that other embodiments alternatively can have any of various other types of electrical-connection schemes to the outlets  456 ,  458 ,  460 ,  462 . For example, connection schemes can be based on spade, lug, or plug connectors, screw connectors, or other suitable type of connector, as discussed above. Furthermore, if desired, one or more of these electrical connectors can be located inside the housing  311  instead of outside the housing as shown in the depicted embodiment. Further alternatively, one or more of these electrical connectors can be located between barrier walls or ridges or other separating structures formed on, or mounted to, the housing  11 . 
       FIG. 5  depicts the front portion  312  of the ganged-outlet housing  311  of the subject embodiment. As discussed above, in the depicted embodiment, four NEMA 5-20R outlets  456 ,  458 ,  460 ,  462  are defined in the front portion  312  of the housing  311 . In certain embodiments, if the front portion  312  is molded of a suitable rigid plastic material, the mold for the front portion  312  is configured to form all the respective outlets in an integral and unitary manner with the front portion  312 . 
     The outlets  456 ,  458 ,  460 ,  462  may be, if desired, molded or formed, or otherwise mounted, within the housing  311  (e.g., to the front portion  312 ) such that adjacent outlets are very close to or even touching each other, and if desired even abutting each other, in a linear array as shown. For example, spacer plates  390  can be positioned between each adjacent outlet to maintain equal spacing between the outlets. Placing the outlets in such close proximity to one another allows the housing  311  to be made as small as possible for mounting in or to the housing of a PDU system (comprising multiple ganged-outlet modules  310 ). Thus, the housing  311  desirably is made to occupy less volume than otherwise would be collectively occupied by an equivalent number of individual outlets separately mounted in a PDU system in the conventional manner. 
     Also, the manner of electrically interconnecting the ganged-outlets  456 ,  458 ,  460 ,  462  in the module  310 , as described above, results in less individualized wiring and the like that otherwise would be required for connecting an equivalent number of outlets, mounted in a PDU system in the conventional manner, to electrical power. Furthermore, mounting the ganged-outlet module  310  into a housing of a PDU system requires substantially less time and effort than individually mounting separate outlets in a PDU system (or other apparatus including multiple outlets) in the conventional manner. 
     Each outlet  456 ,  458 ,  460 ,  462  includes a respective neutral-prong socket  464 , a respective line-prong (“hot-prong”) socket  466 , and a respective ground-prong socket  468 . The neutral-prong sockets  464  are all electrically connected together in parallel by a first power rail or wire (not shown, but see discussion of  FIGS. 6A-6C  below) inside the housing  311  to the neutral-connection terminal  346 . Similarly, the ground-prong sockets  468  are all electrically connected together in parallel by a second power rail or wire (not shown, but the second power rail can be similar to the first power rail shown in  FIGS. 6A-6C ) inside the housing  311  to the ground-connection terminal  344 . Each line-prong socket  466  is electrically connected inside the housing  311  to its respective line-connection terminal  336 ,  338 ,  340 ,  342 . Thus, in a PDU system in which the ganged-outlet module  310  is mounted, line power to each outlet  456 ,  458 ,  460 ,  462  can be individually controlled, for example by connecting line power to the respective connection terminal  336 ,  338 ,  340 ,  342  via a respective switch (not shown). 
       FIGS. 6A-6C  depict an exemplary embodiment of a power rail  688  that can be used in the ganged-outlet module  310  described above. The power rail  688  can be a neutral power rail and comprise a longitudinal power-bus portion  692  from which four neutral-connection elements  694  extend. Also extending from the power-bus portion  692  is the neutral-connection terminal  346 . 
     Turning now to  FIGS. 7 and 8 , the end portions  318  and  320 , respectively, of the housing  311  are shown. In  FIG. 7 , the resilient prong  334  and shoulder  322  can be seen, as well as the connection terminals  336 ,  344 ,  346 . In  FIG. 8 , the resilient prong  328  and shoulder  326  can be seen, as well as the connection terminals  342 ,  344 ,  346 . The end surface  318  ( FIG. 7 ) defines first and second orifices  582 ,  584 , respectively, which can be used to secure various parts  586 ,  588  of the housing  311  together. Similarly, the end surface  320  ( FIG. 8 ) defines first and second orifices  687 ,  689 , respectively, which can be used to secure various parts  691 ,  693  of the housing  311  together. The power rails (not shown) are securely mounted within the housing  311  and are electrically isolated from each other and from the front portion  312  of the housing  311 . 
     Whereas the embodiments of  FIGS. 3-8  depict a ganged-outlet module  310  having four outlets  456 ,  458 ,  460 ,  462 , it will be understood that this number of outlets is exemplary only. Other embodiments of the ganged-outlet module  310  have different respective numbers of outlets (more or less) as needed or desired. 
       FIG. 9  shows a power distribution unit  700  having an alternate exemplary embodiment of a ganged-outlet  708 . The power distribution unit  700  has two outlet gangs  708 , each ganged-outlet  708  has a plurality of interconnected outlets  712  extending through apertures  716  in a housing front section  720  (housing rear section  721  extending opposite and parallel to the housing front section shown removed) of the power distribution unit  700 . Although the outlets  712  are shown as being NEMA 5-20R outlets, any outlet style could be used. For example, the outlets can be other NEMA types (e.g., NEMA 5-15R, NEMA 6-20R, NEMA 6-30R or NEMA 6-50R) or any of various IEC types (e.g., IEC C13 or IEC C19). It also will be understood that all the outlets in a particular ganged-outlet  708  need not be identical. 
     Each of the outlets  712  in a respective outlet gang  708  is connected to a circuit board  724  disposed generally parallel to the housing front section  720 . The circuit board  724  is mounted within the housing  720  and spaced away from the housing front section  720  by nonconductive elongate spacing elements  725  that extend transversely to the circuit board and are coupled to a nonconductive footing  727  mounted to the circuit board (see  FIG. 10 ). The circuit board  724  can be electrically connected to fuse board  728  by one or more wires. For example, in one implementation, the circuit board  724  is electrically connected to the fuse board  728  by an AC power control wire  730  (see  FIG. 10 ) and neutral power supply wire  733 . Further, the power distribution unit can include intelligent power modules having electromechanical relays, e.g.,  729 , electrically connected to the circuit board  724  with each operable to monitor and/or control the power transmitted to a respective individual outlet  712 . 
     Two fuses  734  are connected to the fuse board  728 , with each fuse  734  fusing a respective outlet gang  708  and its associated outlets  712 . The fuses  734  and fuse board  728  are mounted within an aperture  740  penetrating the housing front section  720  at a location intermediate the two outlet gangs  708 . Accordingly, the fuse board  728  and associated fuses  734  are accessible through the aperture  740 . The aperture  740  includes mounting tabs  737  to which a clear or at least partially transparent window  739  can be mounted to allow a user to view the fuses  734  yet provide protection from contact with external objects. 
     Referring to  FIGS. 10 and 11 , each outlet  712  of the outlet gang  708  can have a generally rectangular shaped housing  750  having a generally planar outlet receptacle end portion  752  and four generally planar sides  741 ,  743 ,  745 ,  747  extending generally transversely or perpendicularly from the outlet end portion to an open end portion  754 . The receptacle end  752  desirably is slightly wider and longer than the open end portion  754  to form a shoulder  755  about the perimeter of the front receptacle end  752 . The shoulder may used for mounting the housing  750  to housing front section  720  of PDU  700 . 
     The sides of the housing  750  can include one or more respective outwardly projecting, resilient prongs of locking tabs. For example, in the illustrated embodiments, locking tab  783  is integrally formed in a surface of side portion  783 , and although not shown, a locking tab can be integrally formed in a surface of side portion  745 . Resilient locking tab  783 , being exemplary of the locking tabs of the illustrated embodiments, can be a cantilevered tab, the end of the tab having an outward pointing wedge, formed by gaps between the tab and its surrounding structure on at least a portion of the three sides of the tab. Of course, in other embodiments, the locking tabs can be separate devices attached to the housing  750 . Resilient locking tab  783  is configured to be depressed inwardly (toward the interior of housing  720 ). 
     The resilient tabs, such as tab  783  can be used to facilitate mounting the outlets  712  to housing  750 . This can be accomplished in a manner similar to that described in detail above for securing resilient prongs  328 ,  330 ,  332 ,  334  of the housing  311  to cutouts of a PDU system as shown in  FIG. 3 . In other words, each outlet aperture  716  can be sized such that the housing  750  can be inserted (open end portion  754  first) into a respective aperture  716  until stopped by the shoulder  755 . As this is occurring, the locking tab, or tabs,  783  engages an edge of aperture  716 , is depressed inwardly until insertion progresses past the apice of tab  783 , at which time the tab  783  relaxes outwardly against an edge of the aperture. In this manner, the locking tabs  783  facilitate seating the shoulder  755  against and to a front surface of PDU housing front section  720 . The outlet housings  750  can be removed from respective apertures  716  in a manner similar to that described above in relation to  FIG. 3  for the removal of module  310  from the PDU-system housing. 
     The outlet receptacle end portion  752  includes three power component sockets  713 ,  715 ,  717  formed therein and extending sized to receive a respective power component prong of an electronic device power plug. For example, socket  713 ,  715 ,  717  can be neutral, ground and hot power component sockets, respectively, sized to receive a neutral, ground and hot prong, respectively, of an electronic device plug. 
     Two opposing planar sides  741 ,  745  can each have multiple wire receiving housing recesses  756  coextensive with an outer edge of the open end portion  754 . The recesses  756  can be generally semi-circular shaped to receive power transmitting wires, such as exemplary wires  757 ,  758 ,  760 , which can each transmit a component of AC power, e.g. a neutral, ground or line, i.e., hot, component, respectively, from a power source to an outlet or from one outlet to an adjacent outlet. In the illustrated embodiment, exemplary wires  757  transmit a neutral component of an AC power source, exemplary wires  758  transmit a ground component of an AC power source and exemplary wires  760  transmit a line component of an AC power source. As used herein, the wires can be either one piece of a continuous stretch of wire or a series of coupled wires. 
     Wire  730  can be electrically coupled to the fuse board  728  at a first end and electrically coupled to the printed circuit board  724  at a second end. More specifically, the second end of the wire  730  is removably secured to a wire receptacle  731  in electrical communication with a circuit board  787  that is electrically connected to the printed circuit board  724 . The wire  730  transmits a low current neutral power supply from a power source (not shown) to the circuit board  787 . In one example, the circuit board  787  extends generally parallel and transversely to the printed circuit board  724  along at least a substantially length of the circuit board  724 . 
     One or more microprocessors (not shown), such as an IPM core logic and execution unit, can be mounted to the circuit board  787  and powered by the low current neutral power supply being transmitted to the board via wire  730 . The microprocessors can be in electrical communication with one or more relays  729  and a master communications module (not shown) via a bus, such as an I2C bus. The master communications module can control the microprocessors, which in turn control the regulatory function of the one or more relays  729 . 
     The PDU  700  can also include an AC power supply wire or cable  733  that has a first end coupled to a power source and a second end removably secured to the printed circuit board  724  via a receptacle  735  mounted on the printed circuit board. In the illustrated embodiments, the AC power supply wire transmits the ground, neutral and line components of AC line power from the power source to the printed circuit board  724 . 
     In one specific exemplary implementation, a power distribution unit of the present application can include multiple sets of ganged-outlets with each set having four outlets. For every set, power to each of the four outlets is regulated by a respective one of four relays, with each of the four relays being in electrical communication with a single microprocessor. In other words, a single microprocessor mounted to a board, such as printed circuit board  787 , controls the four relays associated with the four outlets of a given set of ganged-outlets. In this implementation, a separate AC power supply wire or cable is provided for each set of ganged-outlets. In other words, at least one AC power supply cable is electrically connected to a printed circuit board, such as printed circuit board  724 , every four outlets, or relays, to provide power to the outlets of a respective set of outlets. 
     In general, the printed circuit board  724  can have one or more power lines and/or power control lines in power receiving communication with a respective power component of the power source. As will be described below, each power control line is electrically coupled to one or more electrical relays, intelligent power modules, or other power regulating or controlling device. 
     Referring to  FIGS. 12 and 13 , the wires  757 ,  758 ,  760  can be electrically coupled to a respective socket terminal  780 ,  781 ,  782  mounted at least partially within a respective socket  713 ,  715 ,  717 , of housing  750 . The housing  750  can include an interior wall  784  extending within the housing from side  743  of the housing to the opposite side  747  of the housing and extending parallel to the sides  741 ,  745  of the housing. Terminal  780 , being electrically connected to neutral component wires  757 , comprises a neutral component terminal. Plug contact portions  788  of terminal  780  are at least partially disposed within or adjacent the neutral power component socket  713  of the housing  750 . Terminal  781 , being electrically connected to ground wires  758 , comprises a ground component terminal. A plug contact portion  790  of terminal  781  is at least partially disposed within or adjacent the ground power component socket  715  of the housing  750 . Terminal  782 , being electrically connected to a line, or hot, component wire  760 , comprises a line component terminal. A plug contact portion  786  of terminal  782  is at least partially disposed within or adjacent the line power component socket  717  of the housing  750 . 
     The plug contact portions  786 ,  788 ,  790  of the terminals  780 ,  781 ,  782 , respectively, are contacted by the prongs of a plug inserted through the power component sockets  713 ,  715 ,  717  in the housing  750  to establish electrical connectivity between the terminals and the prongs of the plug. For example, a ground prong of a plug of an electrical device inserted into the ground power component socket  715  contacts the plug contact portion  788  of terminal  781  to establish electrically connectivity between the ground prong of the plug and the ground component terminal  781 . 
     As shown in  FIG. 12 , neutral wire  757  can be comprised of several individual lengths of wire, such as first length of wire  757   a  and second length of wire  757   b . The first length of wire  757   a  is electrically connected to a first side of terminal  780  at a first end and electrically connected to a ground terminal of a first adjacent receptacle (not shown) at a second end. The second length of wire  757   b  is electrically connected to a second side of terminal  780  at a first end and electrically connected to a ground terminal of a second adjacent receptacle. In this manner, the neutral terminals of each receptacle or outlet  712  are electrically connected together in parallel by multiple lengths of wire  757  to form wire or rail  757 . 
     Similarly, ground wire  758  can be comprised of several individual lengths of wire, such as first length of wire  758   a  and second length of wire  758   b . The lengths of wire  758   a ,  758   b  are connected to terminal  781  at first ends and adjacent terminals at second ends in a manner similar to that described for wire lengths  758   a ,  758   b.  Accordingly, ground terminals of each receptacle or outlet  712  are electrically connected together in parallel by multiple lengths of wire to form wire or rail  758 . 
     In some implementations, the wires  757 ,  758  can be a single length of wire or comprise a rail-like structure similar to rail  688  shown in  FIGS. 6A-6B . 
     As shown in  FIGS. 10 ,  12  and  13 , wire  760  is electrically connected to terminal  782  inside the housing  750  at a first end and electrically connected to the circuit board  724  at a second end. As shown in the illustrated embodiments, the wire  760  extends from a socket terminal  782  in a direction generally parallel to the circuit board  724 . Proximate the surface  741  of the housing  750 , the wire  760  can be bent at an angle of approximately 90-degrees, to extend generally perpendicular to and towards the circuit board. 
     The second end of the wire  760  opposite the first end can then be electrically coupled or otherwise soldered to the printed circuit board  724 . The second end can be connected to one or more power control lines on or in the printed circuit board  724  to establish electrical power receiving communication with a line component of a power source. Preferably, the wires  760  of each of the respective multiple outlets  712  are connected to separate power control lines each individually electronically connected to a line component of a power source. In other words, line power can be supplied to each receptacle  712  of a ganged-outlet  708  irrespective of other receptacles  712  of the ganged-outlet via separate power lines of the printed circuit board. Desirably, each power control line is electrically connected to a respective intelligent power module or relay  729 . Each relay  729  can be individually and selectively controlled to regulate the line power to a respective line socket terminal  782  and thus the line power to an electrical device plugged into the corresponding outlet  712 . 
     Although an intelligent power module is shown  729 , it is recognized that any of various switches electrically interposed between each of the line terminal  782  and the source of line power can be used. The switches can be manually or electronically actuated, for example. As an example of the latter, the switches can be configured electromechanically such as respective relays, or configured entirely electronically such as respective transistor circuits. 
     Alternatively, in applications where individually controlled outlets are not desired or necessary, instead of one separate portion of transmitting wire  760  for each respective outlet connected to the circuit board, wiring connections to the circuit board can be reduced by electrically connecting one or more line terminals in parallel by multiple lengths or a single length of transmitting wire  760  extending from outlet to outlet in a manner similar to that describe above regarding the interconnectibility of wires  757 ,  758  with neutral terminals  780  and the ground terminal  781  of the outlets. 
     Referring back to  FIG. 11 , each outlet  712  includes an outlet end cap  762  removably secured to the open end  754  of the outlet housing  750 . The end cap  762  can have a generally rectangular shape with a generally closed planar end and four generally planar sides  810 ,  812 ,  814 ,  816  extending generally transversely or perpendicularly from the closed planar end to an open end opposite the closed end. 
     The end cap  762  can include one or more outwardly projecting, resilient prongs or locking tabs, e.g.,  764 . Each resilient prong  764  may be integrally formed in end cap  762  and extend generally transversely from the closed planar end of the end cap  762  toward the open end of the cap. The end of the prongs  764  away from the closed end of the cap can each have an outwardly pointing notch. Each prong  764  is configured to be resiliently depressed inwardly (toward the interior of the cap  762 ). The resilient prongs  764  may be used to facilitate attachment of the cap  762  to the housing  750 . For example, the housing  750  can have orifices formed in the sides of the housing, e.g., orifice  766  formed in side  741  of housing  750 , sized to receive an outwardly pointing notch of a respective cap prong  764 . 
     The end cap  762  includes cap recesses  759  formed in sides  810 ,  814  of the cap. Each recess  759  formed in the sides  810 ,  814  corresponds and is generally alignable with a respective housing recess  756  formed in the sides  741 ,  745 , respectively, of housing  750 . The cap recesses  759  can be generally semi-circular shaped to receive a wire, such as the portion of wire  760  bent towards the printed circuit board. The recess  759  can serve to guide, align and at least partially contain the wire  760 , which can result in increased reliability and manufacturing efficiency. 
     The cap  762  is secured to outlet housing  750  at the open end of the housing  754  by inserting the outwardly pointing notches of the resilient prongs  764  into corresponding apertures  766  in the housing  750 . The cap  762  can be removed by depressing the notches out of engagement with the apertures  766  and withdraw the cap from the housing  750 . 
     With the power transmitting wires secured to respective socket terminals within the housing  750 , the cap  762  can be secured to the housing  750  to at least partially retain the wires within the housing  750 . Further, the cap  762  can be made of a non-conductive material to prevent inadvertent electrical contact between components within the PDU housing  720  and the components within the outlet housing  750 . To assist in preventing inadvertent electrical contact with other components the wires, such as wire  758 , can also be coated with a non-conductive material or include a non-conductive sleeve to prevent inadvertent electrical between the wires and other components within the PDU housing  720 . 
     As can be recognized, the ganged-outlet  708  of  FIGS. 9 and 10  can provide much of the same functionality and insulation as the ganged-outlet module  310  of  FIGS. 1-8 , but without a ganged-outlet housing, such as housing  311 , described above. Accordingly, the ganged-outlet  708  occupies less space, which can allow for more components to be mounted to or positioned within the housing of a PDU system. Further, the ganged-outlet  708  can allow for flexible modification, such as by adding or removing individual outlets  712 , without requiring modification to a ganged-outlet housing. Also, the ganged-outlet  708  can require less wire and labor to assemble in a PDU than that required for typical PDUs without ganged-outlets. 
     The ganged-outlets can have different housing and connector configurations than shown and described above in order to facilitate, for example, interconnection of multiple ganged-outlets together (e.g., in a single PDU system) while minimizing the amount of wiring required for delivering electrical power to the respective ganged-outlets. In other embodiments, the ganged-outlets in their housing or not can be used as a stand-alone ganged-outlet assembly. In yet other embodiments, each ganged-outlet can include additional electrical-connection capability between adjacent ganged-outlets to facilitate their interconnection with each other or otherwise to interconnect them electrically to provide the desired manner in which common, non-controlled power lines are connected to respective outlets of adjacent ganged-outlets. 
     Whereas the disclosure has been set forth above in the context of a representative embodiment and various alternative configurations of that embodiment, it will be understood that the invention is not limited to that embodiment. On the contrary, the invention is intended to encompass any and all embodiments falling within the spirit and scope of the appended claims.