Abstract:
A power transfer device adapted for interconnection with the electrical system of a building includes a cabinet, a set of switches mounted to the cabinet, and wires adapted to connect the switches to an electrical distribution panel associated with a building electrical system. The power transfer device includes a compartment associated with the cabinet, and a selectively configurable cover arrangement for interconnection with the cabinet so as to enclose the compartment. The cover arrangement varies according to the characteristics or parameters of the power transfer device, to provide an optional plug-type power input and an optional power input monitoring arrangement, either alone or in combination with each other, or to provide neither capability. The cover arrangement includes a series of differently configured cover sections which can be mounted to the cabinet in varying combinations, so as to vary the capability of the power transfer device.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to a power transfer device for providing power to the electrical system of a building, such as power supplied from a standby generator. 
     Portable generators are used in certain situations to feed electrical power to residential and commercial load circuits during a utility power outage. These systems frequently include a power inlet box adapted for interconnection with the generator. The power inlet box is typically mounted to the exterior of a building. The power inlet box is connected to a transfer switching mechanism which continues the electrical path through circuit breakers associated with the transfer switching mechanism, to supply power to certain selected circuits of the load center as determined by the transfer switching mechanism selector switches. The circuits of the transfer switching mechanism are wired to selected circuits of the load center, through wiring housed within a conduit extending between the load center and the transfer switching mechanism. 
     The present invention relates to a power transfer arrangement similar to that disclosed in Flegel U.S. Pat. No. 5,895,981 issued Apr. 20, 1999, the disclosure of which is hereby incorporated by reference. In the &#39;981 patent, a power transfer switching mechanism for interposition between a remote power inlet box and the electrical load center of a building includes a terminal compartment for receiving power input wires connected to the remote power inlet box. The switching mechanism includes a cabinet defining an internal cavity within which a series of switches are mounted. The cabinet further defines a terminal compartment, and a terminal assembly is disposed within the terminal compartment. The terminal compartment is accessible through an opening associated with the cabinet, and a cover is selectively positionable over the opening to provide or prevent access to the terminal compartment. A series of wires are interconnected between the terminal assembly and the switches, and power input wiring is received within the terminal compartment and interconnected with the remote power inlet box. The ends of the power input wires are engageable with the terminal assembly for establishing a direct electrical connection between the remote power inlet box and the switches of the switching mechanism. 
     The present invention also relates to power transfer switching mechanisms such as are disclosed in co-pending U.S. patent application Ser. No. 09/062,257 filed Apr. 17, 1998 and Ser. No. 09/139,154 filed Aug. 24, 1998, the disclosures of which are hereby incorporated by reference. The &#39;257 application discloses a power input terminal arrangement in the power transfer switching mechanism, in combination with a removable cover for preventing access to the power input terminal arrangement. The cover is provided with a power inlet or input structure, such as a socket or receptacle, which can be connected to the terminal assembly for selectively receiving a plug connector electrically interconnected with a source of auxiliary power such as a generator. The power transfer switching mechanism in the &#39;257 application provides a transfer switching mechanism which may have either a plug-type power input connection or a direct or hardwired power input connection between the remote power inlet box and the switches of the switching mechanism. The &#39;154 application differs from the &#39;257 application by disclosing a power transfer switching mechanism having a removable cover provided with a power input indicating structure, such as a pair of watt meters, which may be connected to the terminal assembly for selectively displaying the amount of power supplied to the transfer switching mechanism by the generator. In both the &#39;257 application and the &#39;157 application, a blank cover may be used in place of the cover having the power inlet or input structure of having the power input indicating structure, to provide neither plug-type power input nor power input indicating capabilities. 
     Co-pending application Ser. No. 09/157,855 filed Nov. 23, 1998, the disclosure of which is hereby incorporated by reference, discloses a power transfer switching mechanism having a removable cover provided with both a power inlet or input structure as well as a power input indicating structure. The power inlet or input structure may be in the form of a socket or receptacle which is adapted for connection to the terminal assembly for selectively receiving a plug connector and supplying power to the power transfer switching mechanism from a source of auxiliary power such as a generator. As discussed above, this feature provides a selective plug-type power input connection rather than a direct or hardwired power input connection between the generator and the power transfer switching mechanism. The power input indicating structure may be in the form of a pair of watt meters as discussed above, to display the amount of power supplied to the power transfer switching mechanism by the generator. The meters are also used to indicate the balance between the two output circuits of the generator and, during initial setup, to measure the total loads on each individual circuit wired into the transfer circuit. The &#39;855 application thus discloses a cover having a combination plug-type power input and power input indicating system which can be selectively interchanged with a blank cover. 
     Copending application Ser. No. 09/526,237, filed Mar. 15, 2000, discloses an arrangement generally similar to that disclosed in the &#39;257 application as well as the &#39;981 patent, but in which the power input terminal arrangement is replaced with exposed wire leads. The disclosure of the &#39;237 application is hereby incorporated by reference. 
     While the above-described power transfer switching mechanisms provide extremely convenient and simple arrangements for optionally establishing direct, hardwired and selective plug-type connections with the generator or power inlet box and for optionally pending power input monitoring capability, it is desirable to provide a power transfer switching mechanism which can be quickly and easily equipped with a power input receptacle and/or a meter arrangement, or which can be constructed without either a power input receptacle or a meter arrangement. With this modification, the transfer switching mechanism can be configured to receive a power input plug interconnected with the generator if desired, or can be configured to provide a direct, hardwired connection with a remote power inlet. The transfer switching mechanism can also be selectively configured to enable monitoring of the amount of power provided by the generator during a power outage, so as to prevent overloading of and subsequent damage to the generator or to the building electrical system. Although the broad concepts of integrally providing a power input receptacle and meters on a power transfer switching mechanism are well-known, it is desirable to modify the power transfer switching mechanisms described in the aforementioned patents and patent applications, to provide an optional power input and meter arrangement in a cover assembly which can be selectively engaged with the cabinet of the transfer switching mechanism. 
     It is an object of the present invention to provide a transfer switching mechanism having a selectively engageable access cover arrangement capable of providing the transfer switching mechanism with a power input arrangement, a meter arrangement, a combination power input arrangement and meter arrangement, or without either a power input arrangement or a meter arrangement, according to the desired configuration and intended use of the transfer switching mechanism. It is a further object of the present invention to provide such a transfer switching mechanism which is generally similar in construction and operation to known transfer switching mechanisms. It is a further object of the present invention to provide a method for efficiently constructing a power transfer switching mechanism having interchangeable access covers for providing desired functions such as a receptacle-type power input for supplying power from the generator, and a meter panel for monitoring power input from the generators. Yet another object of the invention is to provide such a transfer switching mechanism in which a power input or meter arrangement can be installed or removed at the time of manufacture or at the time of field installation, or retrofitted at a time after installation, at the discretion of the installer or user. 
     In accordance with the invention, a power transfer arrangement is adapted for interconnection in the building electrical system for supplying power from a generator to the electrical system. The power transfer arrangement includes a power inlet arrangement for interconnection with the generator for receiving power therefrom, and a power transfer device separate from the power inlet arrangement adapted for interconnection with the building electrical system. The invention resides in a power input connection arrangement, such as a terminal arrangement or exposed wire leads in the power transfer device, in combination with a selectively configurable cover system adapted for engagement with the power transfer device for preventing access to the power input connection arrangement. In one form, the power transfer device includes a cabinet having a panel to which is mounted a set of switches for controlling the supply of power from the power transfer device to the building electrical system, and the set of switches are electrically connected to the power input connection arrangement. The power input connection arrangement may be in the form of a set of power input terminals or exposed wire leads located within a power input compartment defined by the cabinet at a location spaced from the set of switches. The cabinet defines an open area which provides access to the power terminal compartment. 
     The cover system according to the invention contemplates a pair of separate cover members or sections which are selectively engageable with the power transfer device over the open area of the power transfer device cabinet, for selectively preventing access to the power input compartments. Each cover member or section is engageable with the power transfer device cabinet separately from the other, and the cover members or sections cooperate to enclose the open area of the power transfer device cabinet when the cover members or sections are engaged with the power transfer device cabinet. 
     The cover members or sections may be blank, having nothing more than mounting structure and wall structure which cooperate to mount the cover section to the cabinet and enclose a portion of the open area, or the cover sections may carry certain components useful in operation of the power transfer device, such as a power input member in the form of a socket or a receptacle, or a power input indicating arrangement such as a power meter. The invention contemplates that the pair of cover members or sections which are mounted to the cabinet may be selected from a group of cover sections which includes first, second and third differently configured cover sections. Representatively, each of the first cover sections includes a power input arrangement, each of the second cover sections includes a power input indicating arrangement, and each of the third cover sections is a blank cover section. The pair of cover sections which are selected for mounting to the cabinet over the open area are selected according to the design parameters or operating characteristics of the power transfer device. 
     In one version, a pair of third (blank) cover sections may be selected and mounted to the cabinet over the open area, when it is not desired to provide the power transfer device with either a power input socket or receptacle, or with a power input indicating arrangement. In this version, power is typically supplied to the power transfer device from the generator by wiring a remote power inlet directly to the set of wire leads or terminals contained within the power input compartment, and the blank cover sections simply allow access to the set of wire leads or terminals for establishing the direct connection, and enclose the open area so as to prevent access to the power input compartment after the direct connection has been made. 
     In another version, the selected pair of cover sections include a third (blank) cover section and a first cover section, which includes a power input arrangement. In this version, the power input arrangement, typically a socket or receptacle, is wired to the set of wire leads or terminals and the first cover section is mounted to the cabinet so as to enclose a portion of the open area. The third (blank) cover section is mounted to the cabinet so as to enclose the remainder of the open area. This version is employed when it is desired to provide a plug-type connection to supply power from the generator to the power transfer device. 
     In another version, the selected pair of cover sections include a third (blank) cover section and a second cover section, which includes a power input indicating arrangement such as a meter. In this version, the meter is interconnected with the set of wire leads or terminals or with the power input wiring from the remote power inlet arrangement, and the second cover section is mounted to the cabinet so as to enclose a portion of the open area. The third (blank) cover section is mounted to the cabinet to enclose the remainder of the open area. This version is employed when it is desired to provide the capability to monitor power supplied to the power transfer device by the generator. 
     In yet another version, the selected pair of cover sections include a first cover section and a second cover section, to provide both power input and power indicating capability. In this version, the power input arrangement, such as the socket or receptacle, is wired either to the meter or to the set of wire leads or terminals, and the meter is then wired to the set of terminals or is otherwise interconnected with the power input wiring. In a construction in which the power input socket or receptacle is wired to the wire leads or terminals, a power sensor such as a current transformer is interconnected with the meter and is positioned so as to detect current in the wiring which extends between the power input socket or receptacle and the set of wire leads or terminals. In a construction in which the socket or receptacle is connected to the meter, wires from the meter are then connected to the set of wire leads or terminals for inputting power to the power transfer device from the socket or receptacle through the meter. When mounted to the cabinet, the first and second cover sections cooperate to enclose the open area to prevent access to the power input compartment. 
     With this arrangement, the cover structure of the power transfer device can be varied to provide different functions and operating characteristics for the same basic construction of the power transfer device. That is, a common set of power transfer device components can form the basis for constructing a power transfer device having different functions and characteristics, according to the cover sections which are selected and mounted to the base components of the power transfer device. 
     The invention also contemplates a method of constructing a power transfer device, substantially in accordance with the foregoing summary. 
    
    
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
     FIG. 1 is a schematic representation showing the power transfer arrangement constructed according to the invention for interposition between a remote power inlet arrangement fed by a portable power generator and an electrical panel associated with a building; 
     FIG. 2 is a partial front elevation view showing the bottom portion of the power transfer arrangement of FIG. 1 with a cover construction including both a power input arrangement and a power input indicating arrangement; 
     FIG. 3 is a view similar to FIG. 2, showing a cover construction providing a power input arrangement only; 
     FIG. 4 is a view similar to FIGS. 2 and 3, showing a cover construction providing a power input indicating arrangement only; 
     FIG. 5 is a view similar to FIGS. 2-4, illustrating a cover construction which is blank and provides neither a power input arrangement nor a power input indicating arrangement; 
     FIGS. 6 and 7 are isometric views illustrating cover sections utilized in creating the cover constructions illustrated in FIGS. 2-5; 
     FIG. 8 is a partial, front elevation view showing the bottom portion of the power transfer arrangement of FIG. 1 with the cover sections removed; 
     FIG. 9 is a partial section view taken along line  9 — 9  of FIG. 2; 
     FIG. 10 is a partial section view taken along line  10 — 10  of FIG. 3; and 
     FIG. 11 is a partial section view taken along line  11 — 11  of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a power inlet arrangement, generally similar to that disclosed in the above-referenced patents and/or applications, for interconnecting a portable generator with a main electrical panel or load center  20  located in the interior of a building  22 . In the power inlet arrangement of FIG. 1, a manual power transfer switching mechanism  24  constructed in accordance with the invention is mounted adjacent load center  20  and is interconnected therewith via a series of wires enclosed by a conduit  26  extending between load center  20  and switching mechanism  24 . 
     A power inlet box  28  is mounted to the wall of building  22 , which is shown at  30 . Power inlet box  28  includes an external housing including a series of walls such as  32 , and a recessed power inlet  34  mounted to a front wall of the housing. A cover  36  is mounted to the front wall of the housing via a hinge structure, and is movable between an open position as shown in FIG. 1, and a closed position in which cover  36  encloses recessed power inlet  34  when not in use. A conduit  38  extends from inlet box  28  into the interior of building  22 . Conduit  38  may be connected to a junction box  40  mounted to an interior wall of building  22 . In this embodiment, a flexible cord  42  is attached at one end to junction box  40 , and flexible cord  42  includes a plug-type connector  44  at its opposite end which is adapted for engagement with a power inlet of power transfer switching mechanism  24 , as will be explained. Appropriate connections are made within junction box  40  between cord  42  and the wiring contained within conduit  38 , so as to establish and electrical path between power inlet box  28  and cord connector  44 . Alternatively, as disclosed in U.S. Pat. No. 5,895,981, junction box  40 , cord  42  and connector  44  may be eliminated and conduit  38  may be routed directly to power transfer switching mechanism  24 , such that wires contained within conduit  38  can be connected directly to power input terminals or wire leads located within power transfer switching mechanism  24 . In this construction, power is supplied directly from power inlet box  28  to power transfer switching mechanism  24  without a plug-type connection as is provided by connector  44 . 
     While the drawings illustrate a conduit, such as  38 , extending from inlet box  28  and connected to junction box  40  or connected to power transfer switching mechanism  24  as explained, it is understood that any other approved wiring method may be utilized, such as encased wiring conventionally known as nonmetallic-sheathed cable, for establishing a connection between inlet box  28  and junction box  40  or power transfer switching mechanism  24 . 
     Referring to FIGS. 1 and 8, switching mechanism  24  includes a cabinet  45  defining a pair of side walls  46 ,  48 , a top wall  50  extending between the upper ends of side walls  46 ,  48 , a bottom wall  52  extending between and interconnecting the lower ends of side walls  46 ,  48 , a partial height front panel  54  and a rear panel  56 . Walls  46 - 52 , in combination with front panel  54  and rear panel  56 , define an upper cavity  58  which receives a series of circuit breakers  60  and switches  62  mounted to front panel  54 , in a manner as is known. 
     Referring to FIGS. 9-11, front panel  54  is bent rearwardly at is lower end to form an intermediate transverse wall  64  which defines the lower extent of upper cavity  58 . A lower power input compartment  66  is defined by intermediate transverse wall  64  in combination with bottom wall  52 , the lower portions of side walls  46 ,  48  and the lower portion of rear panel  56 . Lower power input compartment  66  is accessible through an opening or open area located below the lower extent of front panel  54 . 
     Output wires from switches  62 , shown at  68 , extend through lower power input compartment  66  to a conduit fitting  70  secured to bottom wall  52  in a conventional manner, for routing output wires  68  through conduit  26  to load center  20 . Other wires extend through lower compartment  66 , such as neutral and ground wires, as well as input wires from load center  20 . 
     As shown in FIGS. 8-11, switching mechanism  24  includes a series of wires which include end sections  74 , two of which are interconnected with switches  62  through circuit breakers  60 , and lower ends  76  located within lower compartment  66 . Another of wires  72  is a neutral wire adapted for connection to a neutral wire included in wires  68 . Wires  72  further include a ground wire which is connected to both the frame of switching mechanism  24  and to a ground wire included in wires  68 . Wires  72  may be interconnected with transverse wall  64  utilizing grommets  78 . Alternatively, wires  72  may be interconnected through transverse wall  64  or other mounting structure having a transverse wall, such as is disclosed in the above-referenced &#39;237 application. Alternatively, in place of wire lower ends  76 , wires  72  may be connected to a terminal block or the like secured to structure such as transverse wall  64 , in accordance with the disclosure of U.S. Pat. No. 5,895,981. 
     A pair of mounting tabs  80 ,  82  extend upwardly from cabinet bottom wall  52  into the open area through which lower power input compartment  66  is accessible. Mounting tabs  80 ,  82  are provided with threaded openings  84 ,  86 , respectively. 
     A series of aligned slots  88  are formed in transverse wall  64 , slightly inwardly from the intersection of transverse wall  64  with front panel  54 . 
     Referring to FIGS. 2-7, a series of cover sections or members  90 ,  92 ,  94  and  96  are provided for engagement with cabinet  45  of switching mechanism  24  so as to selectively enclose the open area of cabinet  45  which provides access to lower compartment  66 . Cover member  90  includes a power inlet arrangement  98 , cover member  92  includes a power input indicating arrangement  100 , and cover members  94 ,  96  are blank cover members. In a manner to be explained, cover members  90 - 96  are engageable in various combinations with cabinet  45  of switching mechanism  24  so as to vary the characteristics and operation of switching mechanism  24 . 
     As shown in FIGS. 6 and 7, cover members  94 ,  96  are very similar in construction, and defines an inverted L-shape in cross-section. Cover member  94  defines an upper transverse ledge or wall  102  and a depending wall  104 . Similarly, cover member  96  includes an upper transverse ledge or wall  106  and a depending wall  108 . Tabs  110  extend upwardly from transverse upper wall  102  of cover member  94 , and tabs  112  extend upwardly from upper transverse wall  106  of cover member  96 . An opening  113  is formed in depending wall  104  of cover member  94 , slightly offset to the left of center of wall  104 . An opening  115  is formed in depending wall  108  of cover member  96 , and is substantially centrally located relative to depending wall  108 . 
     Depending walls  104 ,  108  are dimensioned such that each of walls  104 ,  108  occupies half of the open area of cabinet  45  which provides access to lower compartment  66 . Tabs  110  are positioned and configured so as to be engageable within two of slots  88  on the left side of lower compartment  66 , with reference to FIG. 8, and tabs  112  are positioned and configured so as to be engageable within the two slots  88  on the right side of lower compartment  66 . When positioned in this manner, opening  113  in depending wall  104  of cover member  94  is in alignment with opening  84  in mounting tab  80 , and opening  115  in depending wall  108  of cover member  96  is in alignment with opening  86  of mounting tab  82 . 
     Cover member  90  has the same structure as cover member  96  as shown and described with respect to FIG. 7, with power inlet  98  mounted thereto, and primed reference characters will be used to facilitate clarity. An opening is formed in depending wall  108 ′ of cover member  90 , and a power input socket, shown generally at  114 , is engaged with wall  108 ′ at the opening. Socket  114  is of conventional construction for receiving a plug connector in a power transfer panel, and includes a cylindrical socket body  116  and a circular collar  118 . Cylindrical socket body  116  extends through the opening in depending wall  108 ′ such that circular collar  118  overlies and engages the front surface of wall  108 ′. A pair of threaded fasteners  120  extend through openings in collar  118  and into engagement with threaded openings formed in depending wall  108 ′, to mount socket  114  to wall  108 ′. In addition, an opening is formed in collar  118  in alignment with the opening in wall  108 ′ which corresponds to opening  115  in wall  108 , and is adapted to receive a fastener  122  which extends therethrough and into engagement with opening  86  in mounting tab  82  adjacent socket  114 , for securing socket  114  to wall  108 ′. 
     Cylindrical socket body  116  defines an outwardly open internal cavity which is closed at its inner end by an end wall  124 . A series of male prongs  126  extend from end wall  124  into the internal cavity defined by socket body  116 . Power input wires  128  are interconnected with prongs  126 . Wires  128  include power, neutral and ground wires interconnected with wire ends  76  and other wires and components as is known, or with a set of input terminals in place of wire ends  76 , for establishing an electrical connection between prongs  126  and switches  62 , as well as with neutral and ground components or wires. 
     In a manner as is known, prongs  126  are adapted for engagement with the female end of plug connector  44 . In this arrangement, plug connector  44  is engaged with prongs  126  for supplying power to power transfer switching mechanism  24  from an electrical generator through power inlet box  28 . Alternatively, a plug connector such as  44  may extend directly from the generator through an opening in wall  30 , such as a window, so as to bypass inlet box  28 . In this arrangement, the cord extends directly from the generator to power transfer switching mechanism  24 , and the plug connector such as  44  is engageable with prongs  126  for supplying power directly to power transfer switching mechanism  24  from the generator. 
     Cover member  92  has the same structure as cover member  94  as shown and described with respect to FIG. 6, and primed reference characters will be used to facilitate clarity. Cover member  92  includes power input indicating structure in the form of a pair of spaced apart watt meters  130 ,  132  which are employed to display the amount of power supplied to power transfer switching mechanism  24 , such as from a standby generator. Each of watt meters  130 ,  132  has a convexly shaped forward portion  134  integrally attached to a block-shaped rear portion  136 . Each forward portion  134  extends through a respective rectangular opening formed in wall  104 ′, and is attached to the inside of wall  104 ′ by one of a pair of spring-biased retainers  138 . Each forward portion  134  defines a transparent window having a support member for mounting a wattage scale  140  visible through the window, and an indicator  142  mounted for movement along scale  140  in response to the supply of generator power. Each rear portion  136  extends rearwardly and perpendicularly to wall  104 ′ and is provided with wires  144 ,  146  interconnected with a current transformer  148  defining an opening  150 . 
     Cover members  90 ,  92 ,  94  and  96  are adapted to be selectively mounted to the base components of power transfer switching mechanism  24  for selectively providing a plug-type power input, a power input monitoring capability, alone or in combination, or for providing neither plug-type input nor power input monitoring. Cover members  90 - 96  can be installed during manufacture, either at an OEM facility or at a distributorship or contractor facility, or can be retrofitted in the field during or after installation. 
     To provide a combination plug-type power input capability as well as power input monitoring capability, both cover members  90  and  92  are secured to cabinet  45  of power transfer switching mechanism  24  as shown in FIG.  2 . Wires  128  of power inlet arrangement  98  are secured to wire ends  76  and other wires and components as is known, or with a set of input terminals utilized in place of wire ends  76 , to establish an electrical connection between power inlet arrangement  98  and switches  62 , as well as with neutral and ground components or wires. Two of the wires  128  are routed one each through opening  150  of each current transformer  148  such that, when power is supplied through wires  128 , each current transformer  148  provides an input to each watt meter  130  indicative of the amount of power being supplied to power transfer switching mechanism  24  from the generator. Alternatively, power inlet arrangement  98  may be wired directly to watt meters  130 ,  132 , which in turn may be connected to wire ends  76  or to terminals utilized in place of wire ends  76 . Cover member  90  is secured in position on power transfer switching mechanism  24  by engaging tabs  112 ′ within the rightward pair of slots  88  and then inserting fastener  122  through the opening in collar  118 , as well as through the opening in wall  108 ′ corresponding to opening  115 , and into engagement with threaded opening  86  in mounting tab  82 . Similarly, cover member  92  is mounted to power transfer switching mechanism  24  by engaging tabs  110 ′ within the leftward pair of slots  88 , and passing the shank of a fastener  152  through the opening in wall  104 ′ which corresponds to opening  113 , and into engagement with threaded opening  84  in mounting tab  80 . 
     To provide a socket-type power input only, cover member  94  is mounted to the cabinet of switching mechanism  24  along with cover member  90 , as shown in FIG.  3 . In this version, cover member  90  is secured as described above, and cover member  94  is engaged with cabinet  45  of power transfer switching mechanism  24  in the same manner as cover member  92 , by inserting tabs  110  into the leftward pair of slots  88  and employing fastener  152  to secure wall  104  to mounting tab  80 . With this construction, cover members  90 ,  94  cooperate to fully enclose the open area which provides access to lower compartment  96 . 
     To provide a power transfer switching mechanism having power input indicating capability only, cover member  92  is employed in combination with cover member  96 , as shown in FIG.  4 . In this version, cover member  92  is secured as described above, and cover member  96  is engaged with cabinet  45  of power transfer switching mechanism  24  in the same manner as cover member  90 , by inserting tabs  112  into the rightward pair of slots  88  and employing a fastener such as  152  to secure wall  108  to mounting tab  82 . Plug-type connector such as  44  is eliminated, and wires are fed directly through a knock-out opening in one of the cabinet walls of power transfer switching mechanism  24  into lower compartment  66 , for direct engagement with wires ends  76  or terminals utilized in place of wire ends  76 . Two of the input wires are routed one each through opening  150  of each current transformer  148 , which provides an input to watt meters  130 ,  132  so as to indicate the amount of power supplied to power transfer switching mechanism  24 . Cover member  92 , in combination with cover member  96 , cooperate to fully enclose the open area which provides access to lower compartment  66 . 
     When it is desired to provide neither plug-type power input nor power input monitoring, cover members  94  and  96  are utilized in combination as shown in FIG.  5 . In this version, fasteners  152  extend through openings  113 ,  115  of walls  104 ,  108 , respectively, and into engagement with threaded openings  84 ,  86 , respectively. Cover members  94  and  96  function to fully enclose the open area of cabinet  45  through which lower compartment  96  is accessible. As with the version of FIG. 4, power input wires are passed through a knock-out opening in one of the walls of cabinet  45  into lower compartment  66 , and are connected to wire ends  76  or to terminals utilized in place of wire ends  76 . 
     It can thus be appreciated that the invention provides a versatile arrangement by which various capabilities can be incorporated in a power transfer switching mechanism, utilizing various combinations of cover members for mounting over an open area defined by the cabinet. 
     While the mounting arrangement by which the various cover members are mounted to the cabinet is illustrated as a tab and slot arrangement in combination with a fastener, it is understood that any other satisfactory releasable or permanent mounting arrangement may be employed. Further, while the drawings illustrate the cover members as having a configuration which corresponds to the configuration of the open area through which the compartment is accessible, it is also understood that the cover members may take other shapes so long as the cover members include surface areas sufficient to enclose the opening through which the compartment is accessible. In addition, while the invention has been described with respect to mounting of either a socket-type power input or a power input indicating arrangement, it is understood that other types of components may be fitted to a transfer switching mechanism utilizing the same type of variably configurable cover system as shown and described, to further enhance the versatility and configurability of the power transfer switching mechanism. 
     Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.