Abstract:
A centralized isolated ground interface apparatus for providing a remote termination point for isolated ground conductors. The apparatus including an isolation transformer for establishing a neutral to ground bond, at least one isolated ground receptacle positioned remotely from the isolation transformer, a battery backup, an electrical interface housing the isolation transformer and positioned remotely from the at least one receptacle, and a bypass switch for bypassing the battery backup without disrupting electrical current transmitted to the at least one isolated ground receptacle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a Continuation-in-Part application of U.S. patent application Ser. No. 10/860,107 filed Jun. 3, 2004, the contents of which are incorporated by reference herein. 
     
    
     TECHNICAL FIELD AND BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to a separately derived isolated ground interface apparatus, and more particularly, to a power interface box for connecting isolated ground (IG) receptacles at a termination point remote from the main electrical service entrance of the facility. 
         [0003]    Isolated ground receptacles, typically orange in color, are used with critical electronic systems to provide a separate ground reference point from the safety or chassis ground required to protect personnel from short circuit voltages in the conduit/raceway system. Critical electronic systems include, but are not limited to, point of sale networks, fueling management systems, computer networks, telecom systems, security systems, automatic teller machines (ATM), internet kiosks, and self checkout point of sale networks. 
         [0004]    Typically, an isolated ground conductor must be routed back to the electrical service entrance grounding terminal of a facility exposing the isolated ground conductor to electrical contamination (noise) by induced voltages from other parallel current carrying conductors that are run in the same conduits, raceways, and panelboards. This electrical contamination compromises the true isolation of the isolated ground conductor thereby reducing its effectiveness. 
         [0005]    The electrical contamination can cause damage, non-operation, or misoperation of electronic components as a result of poor isolation in the grounding path. Thus, there exists a need for a separate termination point for the isolated ground conductor remote of the main service entrance to prevent electrical contamination. 
         [0006]    The National Electrical Code (NEC) allows for alternate wiring of the isolated ground conductor to terminate at a separately derived apparatus. A separately derived apparatus is produced by using an isolation transformer which has separate primary and secondary windings used to provide protection from common mode electrical contamination. The isolation transformer provides an inductive cushion by establishing a neutral to ground bond. This bond prevents the formation and transmission of common mode voltages to electrical devices, such as the critical electronic systems listed above. The separately derived apparatus, therefore, can be used to eliminate electrical contamination associated with long runs of an isolated ground conductor. 
         [0007]    The present invention addresses these problems by providing a separately derived isolated ground interface apparatus utilizing a power interface box capable of providing an interface between the isolation transformer and the remote, hard wired isolated ground receptacles. Thus, the isolated ground interface apparatus provides isolated ground receptacles with a separately derived isolated ground free of electrical contamination. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    Therefore, it is an object of the invention to provide an isolated ground interface apparatus for eliminating electrical contamination of an isolated ground conductor. 
         [0009]    It is another object of the invention to provide an isolated ground interface apparatus that eliminates the need to run an isolated ground conductor back to the main electrical service entrance of the facility. 
         [0010]    It is another object of the invention to provide an isolated ground interface apparatus with a power interface box for providing an interface between an isolation transformer and an isolated ground receptacle. 
         [0011]    It is another object of the invention to provide an isolated ground interface apparatus with an isolation transformer for preventing the transmission of common mode voltages. 
         [0012]    It is another object of the invention to provide an isolated ground interface apparatus with an uninterruptible power supply that has an integral isolation transformer. 
         [0013]    It is another object of the invention to provide an isolated ground interface apparatus with isolated ground receptacles. 
         [0014]    These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an isolated ground interface apparatus for providing a remote termination point for isolated ground conductors. The isolated ground interface apparatus includes an isolation transformer for establishing a neutral to ground bond and thereby preventing transmission of a common mode voltage from an input power supply to an electrical device; at least one isolated ground receptacle for providing a separate ground reference point from a chassis ground for preventing transmission of electrical noise to the electrical device; and an electrical interface for electrically interconnecting the isolation transformer, the input power supply, and the at least one isolated ground receptacle together, whereby the input power supply transmits an electrical current through the electrical interface to the isolation transformer, the isolation transformer providing an isolated ground through the electrical interface to the isolated ground conductor electrically connected to the separate ground reference point of the at least one isolated ground receptacle. 
         [0015]    According to another preferred embodiment of the invention, the isolated ground interface apparatus further includes an emergency power off switch for disconnecting the electrical current supplied from the isolation transformer to the isolated ground receptacles. 
         [0016]    According to another preferred embodiment of the invention, the electrical device includes an electronic device selected from the group consisting of point of sale networks, fueling management systems, computer networks, telecom systems, security systems, automatic teller machines, and internet kiosks. 
         [0017]    According to another preferred embodiment of the invention, the electrical interface includes a bypass switch for bypassing the isolation transformer for allowing service and maintenance to be performed without disrupting the electrical current transmitted to the isolated ground receptacles. 
         [0018]    According to another preferred embodiment of the invention, the electrical interface includes at least one isolated ground termination block for electrically connecting the at least one isolated ground receptacle to the electrical interface. 
         [0019]    According to another preferred embodiment of the invention, the electrical interface includes a female receptacle for receiving a male plug from the isolation transformer. 
         [0020]    According to another preferred embodiment of the invention, the electrical interface includes an input power termination block for electrically connecting the electrical current supplied by the input power supply to the electrical interface. 
         [0021]    According to another preferred embodiment of the invention, the electrical interface includes an emergency power off termination block for electrically connecting the emergency power off switch for disconnecting the electrical current supplied from the isolation transformer to the isolated ground receptacles. 
         [0022]    According to another preferred embodiment of the invention, the electrical interface includes a male plug for connecting the electrical interface to the isolation transformer. 
         [0023]    According to another preferred embodiment of the invention, an isolated ground interface apparatus for providing a remote termination point for isolated ground conductors includes an isolation transformer for establishing a neutral to ground bond and thereby preventing transmission of a common mode voltage from an input power supply to an electronic device; a battery backup for providing an uninterruptible power supply to the electronic device; at least one isolated ground receptacle for providing a separate ground reference point from a chassis ground for preventing transmission of electrical noise to the electronic device; and an electrical interface for electrically interconnecting the isolation transformer, the input power supply, and the at least one isolated ground receptacle together, whereby the input power supply transmits an electrical current through the electrical interface to the isolation transformer, the isolation transformer providing an isolated ground through the electrical interface to the isolated ground conductor electrically connected to the separate ground reference point of the at least one isolated ground receptacle. The electrical interface includes at least one isolated ground termination block for electrically connecting the at least one isolated ground receptacle to the electrical interface; an input power termination block for electrically connecting the electrical current supplied by the input power supply to the electrical interface; and a female receptacle for receiving a male plug from the isolation transformer. 
         [0024]    According to another preferred embodiment of the invention, the electrical interface includes a male plug for electrically connecting the electrical interface to the isolation transformer. 
         [0025]    According to another preferred embodiment of the invention, an electrical interface for an isolated ground interface apparatus having an isolation transformer, an input power supply, and at least one isolated ground receptacle, the electrical interface includes an input power termination block for electrically connecting an electrical current supplied by the input power supply to the electrical interface; at least one isolated ground termination block for electrically connecting the at least one isolated ground receptacle to the electrical interface; a male plug for connecting the electrical interface to the isolation transformer; and a female receptacle for receiving a male plug from the isolation transformer. 
         [0026]    According to another preferred embodiment of the invention, the electrical interface further includes a bypass switch for bypassing the isolation transformer for allowing service and maintenance to be performed without disrupting the electrical current supplied by the input power supply to the isolated ground receptacles. 
         [0027]    According to another preferred embodiment of the invention, the interface further includes an emergency power off termination block for electrically connecting an emergency power off switch for disconnecting the electrical current supplied from the isolation transformer to the isolated ground receptacles. 
         [0028]    According to another preferred embodiment of the invention, a method of providing electrical current supplied by an input power supply to at least one isolated ground receptacle through an isolation transformer using an electrical interface, the electrical interface having a normal mode, wherein the steps of transmitting electrical current to the at least one isolated ground receptacle in the normal mode includes transmitting the electrical current from the input power supply to the electrical interface for transmission of the electrical current to the isolation transformer; transmitting the electrical current from the electrical interface to the isolation transformer for establishing a neutral to ground bond and thereby preventing transmission of a common mode voltage from the input power supply to an electrical device; transmitting the electrical current from the isolation transformer to the electrical interface for transmission of the electrical current to the at least one isolated ground receptacle; transmitting the electrical current from the electrical interface to the at least one isolated ground receptacle for transmission of the electrical current to the electrical device; and a bypass mode, wherein the steps of transmitting electrical current to the at least one isolated ground receptacle in bypass mode includes transmitting the electrical current supplied by the input power supply to the electrical interface for transmission of the electrical current to the at least one isolated ground; and transmitting the electrical current from the electrical interface to the at least one isolated ground for transmission of the electrical current to the electrical device. 
         [0029]    According to another preferred embodiment of the invention, the electrical device includes an electronic device selected from the group consisting of point of sale networks, fueling management systems, computer networks, telecom systems, security systems, automatic teller machines, and internet kiosks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0030]    Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the invention proceeds when taken in conjunction with the following drawings, in which: 
           [0031]      FIG. 1  shows a prior art apparatus for grounding isolated ground receptacles; 
           [0032]      FIG. 2  shows a prior art apparatus for grounding isolated ground receptacles; 
           [0033]      FIG. 3  shows an apparatus for grounding isolated ground receptacles according to the preferred embodiment of the present invention; 
           [0034]      FIG. 4  shows a typical installation of the separately derived isolated ground interface apparatus according to the preferred embodiment of the present invention; 
           [0035]      FIG. 5  shows a wiring diagram for connecting an input power supply, isolated ground receptacles, emergency power off switch, and an isolated transformer to the power interface box; 
           [0036]      FIG. 6  shows a wiring diagram of the internal components of the power interface box operating in normal mode; 
           [0037]      FIG. 7  shows a wiring diagram of the internal components of the power interface box operating in bypass mode; 
           [0038]      FIG. 8  shows an apparatus for grounding isolated ground receptacles wherein the isolation transformer is positioned within power interface box; 
           [0039]      FIG. 9  shows an installation of the apparatus of  FIG. 8  according to another embodiment of the present invention; 
           [0040]      FIG. 10  shows a wiring diagram of the internal components of the power interface box of  FIG. 8  operating in normal mode; and 
           [0041]      FIG. 11  shows a wiring diagram of the internal components of the power interface box of  FIG. 8  operating in bypass mode. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0042]    Referring now specifically to the drawings, a prior art apparatus for providing an uninterruptible power supply to isolated ground receptacles for critical electronics is illustrated in  FIG. 1  and shown generally at reference numeral  10 . 
         [0043]    As shown in  FIG. 1 , electrical current from an input power supply  11  is supplied to a critical panel breaker  12 . The electrical current is supplied in three phases  11 A,  11 B, and  11 C. A neutral  13  and ground  14  of the input power supply  11  are supplied to a critical electronics panelboard  15 . The neutral  13  and ground  14  form a neutral to ground bound  16 . In addition, ground  14  is connected to a grounding electrode system  17  for the facility to provide an isolated ground to the isolated ground receptacles  18 A,  18 B, and  18 C. 
         [0044]    The electrical current  11 A,  11 B, and  11 C are transmitted from the critical panel breaker  12  to the critical electronics panelboard  15  where circuit breakers  20  transmit electrical current  11 A to isolated ground receptacle  18 A, electrical current  11 B to isolated ground receptacle  18 B, and electrical current  11 C to isolated ground receptacle  18 C. The neutral  13  and ground  14  are also connected to isolated ground receptacles  18 A,  18 B, and  18 C. 
         [0045]    The isolated ground is supplied from the ground  14  via isolated ground conductor  21  to an isolated ground termination block  22  located within the critical electronics panelboard  15 . The isolated ground termination block  22  splits the isolated ground conductor  21  into multiple isolated ground conductors  21 A,  21 B, and  21 C to supply an isolated ground to each of the isolated ground receptacles  18 A,  18 B, and  18 C. Plug-in battery backups  23 A,  23 B, and  23 C are plugged into isolated ground receptacles  18 A,  18 B, and  18 C to provide a battery backup to critical electronics  24 A,  24 B, and  24 C. 
         [0046]      FIG. 2  shows another prior art apparatus for providing an uninterruptible power supply to isolated ground receptacles for critical electronics and is shown generally at  30 . Electrical current from an input power supply  31  is supplied to a critical panel breaker  32 . The electrical current is supplied in three phases  31 A,  31 B, and  31 C. A neutral  33  and ground  34  of the input power supply  31  are supplied to a central hardwired battery backup  35 . The neutral  33  and ground  34  form a neutral to ground bound  36 . In addition, ground  34  is connected to a grounding electrode system  37  for the facility to provide an isolated ground to isolated ground receptacles  38 A,  38 B, and  38 C. 
         [0047]    The electrical current  31 A,  31 B, and  31 C are transmitted from the critical panel breaker  32  to the central hardwired battery backup  35 . The electrical current  31 A,  31 B, and  31 C are then transmitted to the critical electronics panelboard  39  where circuit breakers  40  transmit electrical current  31 A to isolated ground receptacle  38 A, electrical current  31 B to isolated ground receptacle  38 B, and electrical current  31 C to isolated ground receptacle  38 C. The neutral  33  and ground  34  are also connected to isolated ground receptacles  38 A,  38 B, and  38 C. 
         [0048]    The isolated ground is supplied from the ground  34  via isolated ground conductor  41  to an isolated ground termination block  42  located within the critical electronics panelboard  39 . The isolated ground termination block  42  splits the isolated ground conductor  41  into multiple isolated ground conductors  41 A,  41 B, and  41 C to supply an isolated ground to each of the isolated ground receptacles  38 A,  38 B, and  38 C. Critical electronics  43 A,  43 B, and  43 C are then plugged into isolated ground receptacles  38 A,  38 B, and  38 C to provide a battery backup to critical electronics  43 A,  43 B, and  43 C. 
         [0049]      FIG. 3  illustrates schematically a separately derived isolated ground interface apparatus  50  according to a preferred embodiment of the present invention for providing an uninterruptible power supply to isolated ground receptacles for critical electronics. The apparatus  50  eliminates the need to run an isolated ground conductor back to the main service entrance preventing the isolated ground conductor from being subjected to electrical contamination associated with long runs. 
         [0050]    Electrical current from an input power supply  51  is supplied to a critical panel breaker  52 . The electrical current is supplied in three phases  51 A,  51 B, and  51 C. Electrical current  51 A is transmitted from the critical panel breaker  52  to an interface  53 , hereinafter referred to as a power interface box. A neutral  54  and ground  55  of the input power supply  51  are also supplied to the power interface box  53 . The neutral  54  and ground  55  form a neutral to ground bound  56 . In addition, ground  55  is connected to a grounding electrode system  57  for the facility. The power interface box  53  transmits the electrical current  51 A, the neutral  54 , and the ground  55  from a female receptacle  84  to an uninterruptible power manager (UPM)  59 , such as the POWERVAR 1440-11, via a male plug  69 . The UPM  59  houses an uninterruptible power supply (UPS)  60  for providing a battery backup, an isolation transformer  61  for providing an isolated ground, a surge diverter (not shown) for diverting a high voltage transient, and a noise filter (not shown) for protecting against a high frequency normal mode noise. However, the uninterruptible power supply  60 , the surge diverter (not shown), and the noise filter (not shown) are not necessary for the apparatus  50  to provide an isolated ground for isolated ground receptacles and may be eliminated if desired. 
         [0051]    The electrical current is conditioned by the UPM  59  and transmitted from female receptacle  69 A to the power interface box  53  via male plug  68 . The conditioned electrical current is then transmitted to isolated ground receptacles  58 A,  58 B, and  58 C. The isolation transformer  61  housed in the UPM  59  provides an isolated ground necessary for isolated ground receptacles  58 A,  58 B, and  58 C by establishing a neutral to ground bond and preventing the transmission of a common mode voltage to the isolated ground receptacles  58 A,  58 B, and  58 C. 
         [0052]    The isolated ground established by the isolation transformer  61  is transmitted to the isolated ground receptacles  58 A,  58 B, and  58 C via the power interface box  53 . An isolated ground conductor  62  is run from the power interface box  53  to an isolated ground termination block  63 . The isolated ground termination block  63  splits isolated ground conductor  62  into multiple isolated ground conductors  62 A,  62 B, and  62 C. Isolated ground conductors  62 A,  62 B, and  62 C are then run from the isolated ground termination block  63  to the isolated ground receptacles  58 A,  58 B, and  58 C providing an isolated ground conductor free of electrical contamination. Critical electronics  64 A,  64 B, and  64 C are then plugged into isolated ground receptacles  58 A,  58 B, and  58 C to provide a battery backup to critical electronics  64 A,  64 B, and  64 C. 
         [0053]      FIG. 4  shows a typical installation of the separately derived isolated ground interface apparatus  50  according to the preferred embodiment of the present invention. The apparatus  50  includes the power interface box  53 , described in detail with reference to  FIGS. 5 and 6 . The power interface box  53  provides an interface between the input power supply  51 , the uninterruptible power manager (UPM)  59 , and isolated ground receptacles  58 A,  58 B, and  58 C. 
         [0054]    The input power supply  51  supplies electrical current to the power interface box  53  via an input conduit  66  running from a circuit breaker box (junction box)  67 . The electrical current is transmitted from the power interface box  53  to the UPM  59  via male plug  69  running from the female receptacle  84  of the power interface box  53  to the UPM  59 . The UPM  59  conditions the electrical current and then transmits the conditioned electrical current from the female receptacle  69 A back to the power interface box  53  via male plug  68 . The conditioned electrical current is then transmitted to isolated ground receptacles  58 A,  58 B, and  58 C and hardwired electronic systems  70  electrically connected to the power interface box  53  by output conduits  71 A and  71 B. 
         [0055]    Optionally, an emergency power off (EPO) switch  72  can be electrically connected to the power interface box  53  via output conduit  71 C to shut the electrical current from the UPM  59  off in the event of an emergency. In addition, an output conduit  71 D can be run from the power interface box  53  back to the junction box  67  to allow isolated ground receptacles  73 A and  73 B to be run directly from the junction box  67 . 
         [0056]      FIG. 5  shows the construction of the power interface box  53 . The input power supply  51  supplies electrical current to the power interface box  53  by a single circuit breaker  74  housed in the junction box  67 . The circuit breaker  74  is electrically connected to an input power termination block  76  within the power interface box  53 . The power interface box  53  houses four output isolated ground termination blocks  77 ,  78 ,  79 , and  80 , for connecting isolated ground receptacles and/or hardwired loads, but any suitable configuration could be used. The output isolated ground termination blocks  77 ,  78 ,  79 , and  80  allow up to three circuits to be installed on one termination block, resulting in a total of up to twelve circuits for four termination blocks. The power interface box  53  also includes an emergency power off (EPO) termination block  81  for installation of the optional EPO switch  72  and an input termination block  82  for connection to the UPM  59 . 
         [0057]    Referring now to  FIGS. 6 and 7 , the power interface box  53  is designed to allow the UPM  59  to be bypassed with bypass switch  83  for service and maintenance. The electrical current supplied by the circuit breaker  74  is electrically connected to line “ 1 ” (L 1 )  76 A, neutral  76 B, and ground  76 C terminals of the input power termination block  76 . The Line “ 1 ” terminal  76 A of the input termination block  76  is directly connected to the bypass switch  83  at contact  83 A and an input power indicator light  86 . 
         [0058]    The neutral terminal  76 B of the input power termination block  76  is electrically connected to the bypass switch  83  at contact  83 F, a female receptacle  84  at terminal  84 B, and the input power indicator light  86 . The ground terminal  76 C of the input power termination block  76  is electrically connected in parallel with ground terminals  77 C,  78 C,  79 C, and  80 C of the four isolated ground termination blocks  77 ,  78 ,  79 , and  80 . The ground terminal  76 C of the input power termination block  76  is also electrically connected to the ground terminal  84 C of the female receptacle  84 . A line terminal  84 A of the female receptacle  84  is also directly connected to the bypass switch  83  at contact  83 A, the input power indicator light  86 , and the line “ 1 ” terminal  76 A of the input power termination block  76 . 
         [0059]    Load terminals  77 A,  78 A,  79 A, and  80 A of the isolated ground termination blocks  77 ,  78 ,  79 , and  80  are electrically connected in parallel with each other and are then electrically connected to the bypass switch  83  at contact  83 B and output power indicator  87 . Isolated ground terminals  77 D,  78 D,  79 D, and  80 D of the isolated ground termination blocks  77 ,  78 ,  79 , and  80  are electrically connected in parallel and are then electrically connected to ground terminal  82 C of the UPM input termination block  82 . Neutral terminals  77 B,  78 B,  79 B, and  80 B are electrically connected in parallel with each other and are then connected to the bypass switch  83  at contact  83 E and output power indicator  87 . 
         [0060]    Line “ 2 ” (L 2 ) terminal  82 A of the UPM input termination block  82  is electrically connected to the bypass switch  83  at contact  83 D via the EPO termination block  81 . Ground terminal  82 C is electrically connected to the parallel ground  84 C and isolated ground  77 D,  78 D,  79 D, and  80 D terminals of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . Neutral terminal  82 B is electrically connected to the bypass switch  83  at terminal  83 C. The male plug  68  supplying electrical current from the UPM  59  is electrically connected to the line “ 2 ”  82 A, neutral  82 B, and ground  82 C terminals of the UPM input termination block  82 . 
         [0061]    In operation, the circuit breaker  74  supplies unconditioned electrical current to terminal  76 A of the input power termination block  76 . The electrical current is then transmitted to the bypass switch  83  at contact  83 A, the female receptacle  84  at terminal  84 A, and to the input power indicator light  86 . The neutral is transmitted to terminal  76 B of the input power termination block  76  and to the bypass switch  83  at contact  83 F, the female receptacle  84  at terminal  84 B, and the input power indicator  86 . The ground is connected to terminal  76 C of the input power termination block and to ground terminals  77 C,  78 C,  79 C, and  80 C of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . The ground is also connected to ground terminal  84 C of the female receptacle  84  and ground terminal  82 C of the UPM input termination block  82 . 
         [0062]    Referring specifically to  FIG. 6 , in normal operation, the bypass switch  83  transmits electrical current to the female receptacle  84  via contacts  83 A and  83 F. The electrical current is then transmitted via the male plug  69  to the UPM  59  where it is conditioned. The conditioned electrical current is then transmitted back to the power interface box  53  from the UPM female receptacle  69 A via the male plug  68 . The UPM input termination block  82  supplies the conditioned electrical current to the bypass switch  83  at contact  83 D to contact  83 B, the conditioned neutral to the bypass switch  83  at contact  83 C to contact  83 E, and the isolated ground to ground terminal  82 C of the input termination block  82  and ground terminals  77 D,  78 D,  79 D, and  80 D of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . The bypass switch  83  then transmits the conditioned electrical current to the load terminals  77 A,  78 A,  79 A, and  80 A of the four isolated ground termination blocks  77 ,  78 ,  79 , and  80  via contact  83 B. The bypass switch  83  then transmits the conditioned neutral to the load terminals  77 B,  78 B,  79 B, and  80 B of the four isolated ground termination blocks  77 ,  78 ,  79 , and  80  via contact  83 E. 
         [0063]    Referring specifically to  FIG. 7 , in bypass operation, the bypass switch  83  eliminates the UPM input termination block  82  and male plug  68  and transmits the unconditioned electrical current directly to the load terminals  77 A,  78 A,  79 A, and  80 A of the isolated ground termination blocks  77 ,  78 ,  79 , and  80  via contacts  83 B and the neutral load terminals  77 B,  78 B,  79 B, and  80 B of the isolated ground termination blocks via contact  83 E. 
         [0064]    Optionally, the emergency power off (EPO) switch  72  can be electrically connected to EPO terminals  81  by removing a wire jumper between a bottom side of terminals  81 A and  81 B and installing the EPO switch  72  in a normally-closed (NIC) wiring configuration. When the EPO switch  72  is activated, the electrical current is removed from terminals  81 A and contact  83 D of the bypass switch  83 , which removes the current from terminal  83 B of bypass switch  83  and line terminals  77 A,  78 A,  79 A, and  80 A of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . 
         [0065]    Referring to  FIGS. 8-11 , an alternative embodiment of an isolated ground interface apparatus  50  is shown for providing an uninterruptible power supply to a plurality of isolated ground receptacles. Referring specifically to  FIG. 8 , the isolation transformer  61  has been relocated from the UPM  59  to the power interface box  53 . In this configuration, the bypass switch operates to bypass the battery backup component only, and the isolation transformer  61  is “online” even when the apparatus is operating in bypass mode. The UPM  59  still includes a UPS  60  for providing battery backup. As in the previous embodiment, the isolation transformer  61  may optionally include a surge diverter and noise filter, and the isolation transformer  61  provides an isolated ground necessary for isolated ground receptacles  58 A,  58 B, and  58 C by establishing a neutral to ground bond and preventing the transmission of a common mode voltage to the isolated ground receptacles. Referring to  FIG. 9 , the UPM  59  shown no longer includes an isolation transformer. 
         [0066]    Referring to  FIGS. 10 and 11 , the power interface box  53  includes a bypass switch  83  for bypassing the battery backup for service and maintenance. The electrical current supplied by the circuit breaker  74  is electrically connected to line “ 1 ” (L 1 )  76 A, neutral  76 B, and ground  76 C terminals of the input power termination block  76 . The Line “ 1 ” terminal  76 A of the input termination block  76  is directly connected to the bypass switch  83  at contact  83 A and an input power indicator light  86 . The neutral terminal  76 B of the input power termination block  76  is electrically connected to the bypass switch  83  at contact  83 F, a female receptacle  84  at terminal  84 B, and the input power indicator light  86 . The ground terminal  76 C of the input power termination block  76  is electrically connected in parallel with ground terminals  77 C,  78 C,  79 C, and  80 C of the four isolated ground termination blocks  77 ,  78 ,  79 , and  80 . The ground terminal  76 C of the input power termination block  76  is also electrically connected to the ground terminal  84 C of the female receptacle  84 . A line terminal  84 A of the female receptacle  84  is also directly connected to the bypass switch  83  at contact  83 A, the input power indicator light  86 , and the line “ 1 ” terminal  76 A of the input power termination block  76 . 
         [0067]    Load terminals  77 A,  78 A,  79 A, and  80 A of the isolated ground termination blocks  77 ,  78 ,  79 , and  80  are electrically connected in parallel with each other and are then electrically connected to the bypass switch  83  at contact  83 B through the isolation transformer  61 . The load terminals  77 A,  78 A,  79 A, and  80 A are also electrically connected to the output power indicator  87 . Isolated ground terminals  77 D,  78 D,  79 D, and  80 D of the isolated ground termination blocks  77 ,  78 ,  79 , and  80  are electrically connected in parallel and are then electrically connected to ground terminal  82 C of the UPM input termination block  82 . Neutral terminals  77 B,  78 B,  79 B, and  80 B are electrically connected in parallel with each other and are then connected to the bypass switch  83  at contact  83 E through the isolation transformer  61 , and also the output power indicator  87 . 
         [0068]    Line “ 2 ” (L 2 ) terminal  82 A of the UPM input termination block  82  is electrically connected to the bypass switch  83  at contact  83 D via the EPO termination block  81 . Ground terminal  82 C is electrically connected to the parallel ground  84 C and isolated ground  77 D,  78 D,  79 D, and  80 D terminals of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . Neutral terminal  82 B is electrically connected to the bypass switch  83  at terminal  83 C. The male plug  68  supplying electrical current from the UPM  59  is electrically connected to the line “ 2 ”  82 A, neutral  82 B, and ground  82 C terminals of the UPM input termination block  82 . 
         [0069]    In operation, the circuit breaker  74  supplies unconditioned electrical current to terminal  76 A of the input power termination block  76 . The electrical current is then transmitted to the bypass switch  83  at contact  83 A, the female receptacle  84  at terminal  84 A, and to the input power indicator light  86 . The neutral is transmitted to terminal  76 B of the input power termination block  76  and to the bypass switch  83  at contact  83 F, the female receptacle  84  at terminal  84 B, and the input power indicator  86 . The ground is connected to terminal  76 C of the input power termination block and to ground terminals  77 C,  78 C,  79 C, and  80 C of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . The ground is also connected to ground terminal  84 C of the female receptacle  84  and ground terminal  82 C of the UPM input termination block  82 . 
         [0070]    Referring specifically to  FIG. 10 , in normal operation, the bypass switch  83  transmits electrical current to the female receptacle  84  via contacts  83 A and  83 F. The electrical current is then transmitted via the male plug  69  to the UPM  59  where it is conditioned. The conditioned electrical current is then transmitted back to the power interface box  53  from the UPM female receptacle  69 A via the male plug  68 . The UPM input termination block  82  supplies the conditioned electrical current to the bypass switch  83  at contact  83 D to contact  83 B, the conditioned neutral to the bypass switch  83  at contact  83 C to contact  83 E, and the isolated ground to ground terminal  82 C of the input termination block  82  and ground terminals  77 D,  78 D,  79 D, and  80 D of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . The bypass switch  83  then transmits the conditioned electrical current to the load terminals  77 A,  78 A,  79 A, and  80 A of the four isolated ground termination blocks  77 ,  78 ,  79 , and  80  via contact  83 B. The bypass switch  83  then transmits the conditioned neutral to the load terminals  77 B,  78 B,  79 B, and  80 B of the four isolated ground termination blocks  77 , 78 ,  79 , and  80  via contact  83 E. 
         [0071]    Referring specifically to  FIG. 11 , in bypass operation, the bypass switch  83  eliminates the UPM input termination block  82  and male plug  68  and transmits the unconditioned electrical current directly to the load terminals  77 A,  78 A,  79 A, and  80 A of the isolated ground termination blocks  77 ,  78 ,  79 , and  80  via contacts  83 B and the neutral load terminals  77 B,  78 B,  79 B, and  80 B of the isolated ground termination blocks via contact  83 E. 
         [0072]    Optionally, the emergency power off (EPO) switch  72  can be electrically connected to EPO terminals  81  by removing a wire jumper between a bottom side of terminals  81 A and  81 B and installing the EPO switch  72  in a normally-closed (N/C) wiring configuration. When the EPO switch  72  is activated, the electrical current is removed from terminals  81  A and contact  83 B of the bypass switch  83 , which removes the current from terminal  83 B of bypass switch  83  and line terminals  77 A,  78 A,  79 A, and  80 A of the isolated ground termination blocks  77 ,  78 ,  79 , and  80 . 
         [0073]    In any of the various embodiments provided herein, the apparatus may further include a remote monitoring system ( FIG. 3  at  100 ) including remote signaling of input and output power status, such as through a building automation interface for controlling other systems including, but not limited to, security, lighting and ventilation systems. Remote monitoring may include remote diagnostics and a display. Remote monitoring may take place within the facility in which the apparatus is installed or in a remote location. 
         [0074]    A separately derived isolated ground interface apparatus utilizing a power interface box capable of providing an interface between an isolation transformer and a remote, hard-wired isolated ground receptacle is described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiments of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation, the invention being identified in the claims.