Building power supply system

Abstract

To provide a power supply system for a building capable of surely informing a user of occurrence of ground fault without increasing the number of electric component boxes while preventing indoor design characteristics from being impaired.SOLUTION: A power supply system includes: a power supply path 22 for supplying commercial power from a distribution board 11 to an electric apparatus in a building; an inlet 31 to which an automobile 23 is connected via a power supply cable 27; a connection path 35 for connecting the inlet 31 and the power supply path 22; and a changeover switch 21 for switching the power supplied to the electric apparatus between commercial power and power of the automobile 23. The power supply system includes: an insulation transformer 41 provided in the connection path 35; a ground fault detection unit 42 that detects a ground fault current when a ground fault occurs in the power supply cable 27; and an alarm 43 that notifies occurrence of the ground fault. The ground fault detection unit 42, the alarm 43, and the changeover switch 21 are housed in an electrical box 51, and the insulation transformer 41 is housed in an electrical box 52.SELECTED DRAWING: Figure 2

Description

[[Technical Field]]

[0001] The present invention relates to a power feeding system for a building. [[Background Art]]

[0002] Patent Document 1 discloses a power feeding system capable of supplying electric power to electrical devices in a building from an external power supply device different from a commercial power supply when a power outage occurs in the building due to a disaster or the like. In the power feeding system of Patent Document 1, as shown in Fig. 5, commercial power is supplied from a commercial power supply (not shown) to a distribution board 81 provided in a building 80, and the supplied commercial power is supplied from the distribution board 81 through a commercial power feeding path 82 to an electrical device 84 in the building 80.

[0003] In the power feeding system of Patent Document 1, an automobile 85 (specifically, an on-vehicle battery) is assumed as the external power supply device, and electric power can be supplied from the automobile 85 to the electrical device 84 in the building 80. As a configuration for this purpose, the power feeding system of Patent Document 1 is provided with an inlet 88 to which the automobile 85 can be connected via a power feeding cable 87, and an external power feeding path 89 for supplying the electric power of the automobile 85 from the inlet 88 to the electrical device 84. Further, the power feeding system of Patent Document 1 is provided with a changeover switch 91 that is respectively connected to the commercial power feeding path 82 and the external power feeding path 89, and switches which of the commercial power and the electric power of the automobile 85 is to be supplied to the electrical device 84. Thus, during a power outage of the building 80, by connecting the automobile 85 to the inlet 88 via the power feeding cable 87 and switching the power supply source to the automobile 85 side by the changeover switch 91, the electric power of the automobile 85 can be supplied to the electrical device 84 via the power feeding cable 87 and the external power feeding path 89. Note that the changeover switch 91 is provided in a state of being accommodated in an electrical equipment box 92 (housing).

[0004] By the way, in the power supply system described above, when power is supplied from the automobile 85 to the electrical equipment 84 on the building 80 side via a power supply cable 87, if the insulation coating of a part of the power supply cable 87 is damaged due to deterioration or trauma, the power supply cable 87 may be electrically connected (grounded) to the ground at the damaged point, potentially causing a ground fault. Therefore, the power supply system of Patent Document 1 is equipped with an external power supply device 93 that detects the occurrence of a ground fault in the power supply cable 87 and notifies the user. The configuration of the external power supply device 93 will be described below.

[0005] As shown in Figure 6, the external power supply device 93 includes an isolation transformer 95, a ground fault detection unit 96, an alarm 97, and an electrical box 98 (housing) that houses these components 95 to 97. The isolation transformer 95 is installed in the external power supply path 89, and the primary side of the isolation transformer 95 in the external power supply path 89 is grounded via the grounding path 99. The ground fault detection unit 96 detects the ground fault current flowing through the grounding path 99 when a ground fault occurs in the power supply cable 87. The alarm 97 notifies the user of the occurrence of a ground fault when the ground fault current is detected by the ground fault detection unit 96. This makes it possible to notify the user of the occurrence of a ground fault in the power supply cable 87 when power is being supplied from the automobile 85 to the electrical equipment 84. The electrical box 98 is mounted on an indoor wall or the like.

[0006] When a ground fault occurs in the power supply cable 87, as shown in Figure 7, a ground fault current (see dotted arrow) flows through the fault location T and the grounding path 99. In this case, since an isolation transformer 95 is provided in the external power supply path 89, the current path through which the ground fault current flows is formed only on the primary side of the isolation transformer 95. In other words, in this case, the ground fault current does not flow to the secondary side (electrical equipment 84 side) of the isolation transformer 95, so that the minute current of the ground fault can be reliably flowed through the grounding path 99. As a result, the ground fault detection unit 96 can reliably detect the ground fault current, and as a result, it is possible to reliably notify the user when a ground fault occurs. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2022-041045 [Overview of the project] [Problems that the invention aims to solve]

[0008] By the way, among the components 95 to 97 housed in the electrical box 98 of the external power supply device 93, the isolation transformer 97 is a relatively large component. Therefore, in the power supply system of Patent Document 1, it is considered necessary to enlarge the size of the electrical box 99 to match the size of the isolation transformer 97. However, if the electrical box 99 is enlarged, there is a risk that the aesthetic design of the interior will be compromised if the electrical box 99 (i.e., the external power supply device 93) is mounted on the wall of a living space.

[0009] Therefore, it is conceivable to install the electrical box 99 on the wall of a non-living space such as a storage room. However, if this is done, it is anticipated that the user may not notice the alarm 97 when it signals the occurrence of a ground fault.

[0010] Alternatively, it is possible to provide separate electrical boxes for the isolation transformer 95 and the alarm device 97. In this case, the electrical box for the isolation transformer would be relatively large and therefore installed in a non-residential space, while the electrical box for the alarm device could be made smaller and installed in a residential space. This would allow for reliable notification of a ground fault to the user while minimizing any damage to the interior design.

[0011] However, if electrical boxes are separated into those for the isolation transformer and those for the alarm system, the number of electrical boxes will increase, which could lead to disadvantages such as increased manufacturing costs. Furthermore, since there is also an electrical box for the changeover switch, considering that as well, increasing the number of electrical boxes is undesirable.

[0012] This invention has been made in view of the above circumstances, and its main objective is to provide a building power supply system that can reliably notify the user of a ground fault when one occurs, without increasing the number of electrical boxes and without compromising the aesthetic design of the interior. [Means for solving the problem]

[0013] To solve the above problems, the building power supply system of the first invention comprises a distribution board to which commercial power is supplied from a commercial power source, a commercial power supply path for supplying the commercial power from the distribution board to electrical equipment in the building, a connection part to which an external power supply device installed outdoors is connected via a power supply cable, an external power supply path for supplying the power of the external power supply device supplied to the connection part via the power supply cable to the electrical equipment from the connection part, and a connection to the commercial power supply path and the external power supply path, respectively, which of the commercial power and the power of the external power supply device A building power supply system comprising: an isolation transformer provided in the external power supply path; a grounding path that grounds the primary side of the isolation transformer in the external power supply path; a ground fault detection unit that detects ground fault current flowing through the grounding path when a ground fault occurs in the power supply cable; a notification unit that notifies of the occurrence of a ground fault when a ground fault current is detected by the ground fault detection unit; a first electrical equipment box housing the ground fault detection unit, the notification unit and the switching operation unit; and a second electrical equipment box housing the isolation transformer.

[0014] According to the first invention, the ground fault detection unit, notification unit, and switching operation unit are housed in the first electrical equipment box, and the isolation transformer is housed in the second electrical equipment box. In this case, since the relatively large isolation transformer is housed in the second electrical equipment box, which is separate from the first electrical equipment box, the first electrical equipment box can be made smaller. Therefore, even if the first electrical equipment box is installed on the wall of a living space, it is possible to suppress any deterioration in the aesthetic design of the interior. Furthermore, by installing the first electrical equipment box on the wall of a living space, if a ground fault in the power supply cable is detected by the notification unit housed in the first electrical equipment box, the user can be reliably notified of this fact.

[0015] Furthermore, the first electrical box houses the switching operation unit instead of the isolation transformer. Since the switching operation unit is smaller than the isolation transformer, this configuration also allows for miniaturization of the first electrical box. In addition, by housing the switching operation unit in the first electrical box, a separate electrical box for the switching operation unit can be eliminated. Therefore, even while providing a second electrical box to house the isolation transformer, it is possible to avoid increasing the total number of electrical boxes. As a result, it is possible to reliably notify the user of a ground fault in the power supply cable without increasing the number of electrical boxes or compromising the aesthetic design of the interior.

[0016] The power supply system for a building of the second invention is such that, in the first invention, the first electrical box and the second electrical box are mounted on the same wall facing the living space, and the isolation transformer is housed in the second electrical box with a portion of it protruding into the wall.

[0017] Generally, isolation transformers have a large thickness, so if the entire isolation transformer is housed in the second electrical box, the depth (thickness) of the second electrical box becomes large. In that case, if the second electrical box is attached to a wall, there is a risk that the second electrical box will protrude significantly from the wall. Therefore, in the second invention, the isolation transformer is housed in the second electrical box with a portion of it recessed into the wall. In this case, the depth of the second electrical box can be reduced, and thus the amount of protrusion from the wall of the second electrical box can be reduced. As a result, even if the second electrical box is attached to a wall facing the living space, the deterioration of the interior design can be suppressed.

[0018] Furthermore, the first and second electrical boxes are mounted on the same wall facing the living space. Therefore, all components for external power supply (isolation transformer, ground fault detection unit, notification unit) and the switching operation unit for switching the power source can be consolidated on the same wall. This makes it easier to construct the power supply system, for example, by shortening the wiring connecting the components.

[0019] In the third invention, the building power supply system is such that, in the second invention, the first electrical box and the second electrical box are attached to the wall portion on which the distribution board is installed.

[0020] According to the third invention, the first electrical box and the second electrical box are mounted on the wall where the distribution board is installed. In this case, the distribution board that supplies commercial power, the components for external power supply (isolation transformer, ground fault detection unit, notification unit), and the switching operation unit for switching the power source can all be integrated on the same wall. This makes it even easier to construct this power supply system. [Brief explanation of the drawing]

[0021] [Figure 1] A diagram showing the overall configuration of the power supply system. [Figure 2] A diagram showing the electrical configuration of an external power supply device. [Figure 3]A diagram for explaining a ground fault current that flows when a ground fault occurs in a power feeding cable. [Figure 4] (a) is a front view showing an installation state of an electrical equipment box with respect to a wall part, and (b) is a cross-sectional view taken along line A-A of (a). [Figure 5] A diagram showing an overall configuration of a power feeding system of Patent Document 1. [Figure 6] A diagram showing an electrical configuration of an external power feeding device in the power feeding system of Patent Document 1. [Figure 7] A diagram for explaining a ground fault current that flows when a ground fault occurs in a power feeding cable in the power feeding system of Patent Document 1. MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of the power feeding system.

[0023] As shown in FIG. 1, a distribution board 11 is provided in a building 10 such as a house. Commercial power transmitted from a commercial power source (not shown) is supplied to the distribution board 11 via a service line 12. The service line 12 is led into the building 10 side from a pole transformer (not shown) installed on a utility pole. In the pole transformer, AC 6600V high-voltage power (commercial power) flowing through a distribution line is converted into AC 100 / 200V low-voltage power. Then, the converted low-voltage power is supplied to the distribution board 11 via the service line 12. Note that the secondary side of the pole transformer is grounded.

[0024] The AC 100 / 200V commercial power supplied to the distribution board 11 is distributed from the distribution board 11 to multiple circuits (branch circuits) within the building 10. These multiple circuits include a living room circuit 15, which is a circuit for the living room. The living room circuit 15 has electrical equipment such as lighting fixtures 16, lighting switches 17, and outlets 18, and unit cables 19 connected to these electrical equipment 16-18. The distribution board 11 and the living room circuit 15 are connected via a power supply path 22, and commercial power is supplied from the distribution board 11 to the living room circuit 15 (each electrical equipment 16-18) through this power supply path 22. Note that the power supply path 22 corresponds to the commercial power supply path. Also, for convenience, in Figure 1, circuits other than the living room circuit 15 within the building 10 are omitted from the illustration.

[0025] Building 10 is equipped with an external power supply system that allows the living room circuit 15 to be powered from an external power supply unit. This means that in the event of a power outage in Building 10 due to a disaster or other reason (i.e., when the supply of commercial power is interrupted), it is possible to connect an external power supply unit to Building 10 and supply power from the external power supply unit to the living room circuit 15 while the unit is connected. Therefore, even in the event of a power outage, it is possible to use the electrical appliances 16-18 in the living room.

[0026] Furthermore, since the living room circuit 15 can supply power even in emergencies, it can also be called an emergency power supply circuit. Also, the emergency power supply circuit does not necessarily have to be the living room circuit 15; it could be another circuit, such as a bedroom circuit for the bedroom. Additionally, multiple emergency power supply circuits may be configured.

[0027] Next, we will explain the configuration for supplying power to the living room circuit 15 from an external power supply unit.

[0028] In this embodiment, an automobile 23 with an external power supply function is assumed as the external power supply device. The automobile 23 is, for example, a plug-in hybrid vehicle (PHV) equipped with an on-board battery 24. The automobile 23 is provided with an electrical outlet 25 inside the vehicle. The outlet 25 is electrically connected to the on-board battery 24, and power stored in the on-board battery 24 can be drawn from the outlet 25. The outlet 25 is an AC 100V outlet, the same as an outlet provided in a building. Therefore, electrical appliances (household appliances) such as hair dryers can be connected to the outlet 25.

[0029] The automobile 23 can be connected to the building 10 via a power supply cable 27. The power supply cable 27 has a pair of connectors 27a and 27b at both ends. Of these connectors 27a and 27b, one connector 27a can be connected to the outlet 25 of the automobile 23, and the other connector 27b can be connected to an inlet 31 provided on the outer wall 29 of the building 10. As a result, the automobile 23 and the building 10 are electrically connected via the power supply cable 27, with connector 27a of the power supply cable 27 connected to the outlet 25 of the automobile 23 and connector 27b connected to the inlet 31 of the building 10. Outdoors, a parking space 32 for the automobile 23 is provided adjacent to the building 10, and the inlet 31 is provided on the outer wall 29 facing the parking space 32. The inlet 31 also corresponds to the connection point.

[0030] Building 10 is provided with a connection path 35 that connects the inlet 31 to the power supply path 22. The connection path 35 is connected to the middle section of the power supply path 22, and a changeover switch 21 is provided at the connection point between the power supply path 22 and the connection path 35. In this case, the changeover switch 21 and the inlet 31 are connected via the connection path 35.

[0031] The changeover switch 21 can be manually switched between a first position, which connects the distribution board 11 and the living room circuit 15, and a second position, which connects the inlet 31 (in other words, the connection path 35) and the living room circuit 15. When the changeover switch 21 is in the first position, commercial power is supplied from the distribution board 11 to the living room circuit 15 via the power supply path 22. The changeover switch 21 is normally set to the first position, and Figure 1 shows the changeover switch 21 in the first position. Note that the changeover switch 21 corresponds to the changeover operation unit.

[0032] On the other hand, when the changeover switch 21 is switched from the first position to the second position while the car 23 (specifically the outlet 25) is connected to the inlet 31 on the building 10 side via the power supply cable 27, the car 23 and the living circuit 15 are electrically connected via the power supply cable 27, the connection path 35, and a part of the power supply path 22 (specifically, the part of the power supply path 22 that connects the changeover switch 21 and the living circuit 15). In this case, AC 100V power is supplied from the car 23 side to the inlet 31 via the power supply cable 27, and this supplied power is then supplied from the inlet 31 to the living circuit 15 via the connection path 35 and the aforementioned part of the power supply path 22. In this case, the connection path 35 and the aforementioned part of the power supply path 22 constitute an external power supply path.

[0033] Here, the power supply system is equipped with an external power supply device 40 that detects ground faults in the power supply cable 27 when power is supplied from the automobile 23 to the living circuit 15 via the power supply cable 27 (external power supply). The configuration of the external power supply device 40 will be described below with reference to Figure 2. Figure 2 is a diagram showing the electrical configuration of the external power supply device 40.

[0034] As shown in Figure 2, the external power supply device 40 includes an isolation transformer 41, a ground fault detection unit 42, an alarm 43, and a residual current circuit breaker 44. The isolation transformer 41 is located in the connection path 35. The primary side of the isolation transformer 41 is connected to the inlet 31, and the secondary side is connected to the changeover switch 21. Furthermore, the size (volume) of the isolation transformer 41 is sufficiently larger than that of the ground fault detection unit 42, the alarm 43, and the residual current circuit breaker 44.

[0035] In the connection path 35, the primary side of the isolation transformer 41 is grounded via the grounding path 49. The grounding path 49 is equipped with a ground fault detection unit 42. The ground fault detection unit 42 consists of a current sensor and detects the ground fault current flowing through the grounding path 49 when a ground fault occurs in the power supply cable 27.

[0036] Figure 3 shows the ground fault current that flows when a ground fault occurs in the power supply cable 27. As shown in Figure 3, when a ground fault (single-line ground fault) occurs in the power supply cable 27, a ground fault current flows through the fault location T and the grounding path 49. In Figure 3, the current path through which the ground fault current flows is indicated by a dotted arrow. In this case, the current path through which the ground fault current flows is formed (only) on the primary side of the isolation transformer 41. In other words, in this case, the ground fault current does not flow to the secondary side (living circuit 15 side) of the isolation transformer 41, so the minute current of the ground fault can be reliably flowed to the grounding path 49. As a result, the ground fault detection unit 42 can reliably detect the ground fault current.

[0037] The alarm device 43 notifies the user of a ground fault in the power supply cable 27 when a ground fault current is detected by the ground fault detection unit 42. The alarm device 43 consists of, for example, a buzzer and notifies the user of a ground fault by outputting an alarm sound. In addition to a buzzer, the alarm device 43 may also use a light-emitting unit such as a lamp to provide notification by emitting light. When a ground fault current is detected by the ground fault detection unit 42, the alarm device 43 outputs an alarm sound based on that detection. This allows the user to be notified of the occurrence of a ground fault. The alarm device 43 corresponds to the notification unit.

[0038] The earth leakage circuit breaker 44 is installed on the secondary side of the isolation transformer 41 in the connection path 35. When power is supplied from the automobile 23 to the living circuit 15 via the power supply cable 27 and the connection path 35, the earth leakage circuit breaker 44 will trip the connection path 35 if an earth leakage occurs on the secondary side of the isolation transformer 41 (living circuit 15 side). Although not shown in the diagram, the connection path 35 is grounded at a point that is both the secondary side of the isolation transformer 41 and the primary side of the earth leakage circuit breaker 44.

[0039] The external power supply device 40 includes electrical boxes 51 and 52 that house the aforementioned components 41 to 44. Electrical boxes 51 and 52 include electrical box 51, which houses the ground fault detection unit 42 and the alarm 43, and electrical box 52, which houses the isolation transformer 41 and the earth leakage circuit breaker 44. Both electrical boxes 51 and 52 are made of resin housings and are formed to be the same size. Electrical box 51 also houses a changeover switch 21. Electrical box 51 corresponds to the first electrical box, and electrical box 52 corresponds to the second electrical box.

[0040] Each electrical box 51 and 52 is mounted on a wall inside the building 10. The mounting state of the electrical boxes 51 and 52 to the wall will be described below with reference to Figure 4. Figure 4 shows (a) a front view of the mounting state of the electrical boxes 51 and 52 to the wall, and (b) a cross-sectional view of (a) along line AA.

[0041] As shown in Figures 4(a) and (b), the wall section 55 is provided facing the living space 56 and is composed of a plurality of wall panels 57 arranged side by side. The living space 56 is, for example, a washroom. However, the living space 56 may be a corridor, a living room, or the like.

[0042] The distribution board 11 and the electrical boxes 51 and 52 are mounted on the wall surface of the wall section 55. The distribution board 11 is located at the top of the wall section 55, while the electrical boxes 51 and 52 are located below the distribution board 11. Specifically, the distribution board 11 and the electrical boxes 51 and 52 are mounted on the same wall panel 57 of the wall section 55. The electrical boxes 51 and 52 are also arranged side by side in the width direction of the wall section 55. The wiring constituting the connection path 35 and the grounding path 49 is routed through the inside of the wall section 55.

[0043] The electrical box 51 has two openings 58 and 59 formed on its front (front panel) portion. Of these openings 58 and 59, opening 58 is formed in a position corresponding to the alarm device 43, and an alarm sound is output from the alarm device 43 through this opening 58. Opening 59 is formed in a position corresponding to the changeover switch 21, and switching operations by the changeover switch 21 can be performed through this opening 59. Note that there are no openings at all on the front portion of the electrical box 52.

[0044] The isolation transformer 41 housed in the electrical box 52 has a wall portion 55 with a thickness dimension L1 greater than the depth dimension L2 (thickness dimension) of the electrical box 52. The isolation transformer 41 is housed in the electrical box 52 with a portion of it embedded inside the wall portion 55. Specifically, a through hole (not shown) is formed in the back (back panel) of the electrical box 52 through which the isolation transformer 41 is inserted, and a portion of the isolation transformer 41 is embedded inside the wall portion 55 through this through hole. In addition, a cylindrical portion 61 is provided on the back of the electrical box 52 that surrounds the portion of the isolation transformer 41 that is embedded in the wall portion 55. The cylindrical portion 61 is integrated with the electrical box 52 and is embedded inside the wall portion 55.

[0045] As described in detail above, the configuration of this embodiment provides the following excellent effects.

[0046] The ground fault detection unit 42, alarm 43, and changeover switch 21 are housed in the electrical box 51, and the isolation transformer 41 is housed in the electrical box 52. In this case, since the relatively large isolation transformer 41 is housed in the electrical box 52, which is separate from the electrical box 51, the electrical box 51 can be made smaller. Therefore, even if the electrical box 51 is installed on the wall 55 of the living space 56, the aesthetic design of the interior can be minimized. In addition, by installing the electrical box 51 on the wall 55 of the living space 56, if a ground fault in the power supply cable 27 is detected by the alarm 43 housed in the electrical box 51, the user can be reliably notified.

[0047] Furthermore, the electrical box 51 houses a changeover switch 21 instead of an isolation transformer 41. Since the changeover switch 21 is smaller than the isolation transformer 41, this configuration also allows for miniaturization of the electrical box 51. In addition, by housing the changeover switch 21 in the electrical box 51, a separate electrical box for the changeover switch 21 can be eliminated. Therefore, while still providing an electrical box 52 to house the isolation transformer 41, it is possible to avoid increasing the total number of electrical boxes. As a result, it is possible to reliably notify the user of a ground fault in the power supply cable 27 without increasing the number of electrical boxes or compromising the aesthetic design of the interior.

[0048] Generally, isolation transformers 41 have a large thickness, so if the entire isolation transformer 41 is housed in the electrical box 52, the depth (thickness) of the electrical box 52 becomes large. In that case, if the electrical box 52 is attached to a wall, there is a risk that the electrical box 52 will protrude significantly from the wall. Therefore, in the above embodiment, the isolation transformer 41 is housed in the electrical box 52 with a portion of it recessed into the wall 55. In this case, the depth of the electrical box 52 can be reduced, and thus the amount of protrusion of the electrical box 52 from the wall 55 can be reduced. As a result, even if the electrical box 52 is attached to a wall 55 facing the living space 56, the deterioration of the interior design can be suppressed.

[0049] Furthermore, each electrical box 51, 52 is mounted on the same wall 55 facing the living space 56. Therefore, all components for external power supply (isolation transformer 41, ground fault detection unit 42, alarm 43) and the changeover switch 21 for switching the power source can be consolidated on the same wall 55. This makes it easier to construct the power supply system, for example, by shortening the wiring connecting the components.

[0050] The electrical boxes 51 and 52 are mounted on the wall 55 to which the distribution board 11 is installed. In this case, the distribution board 11 that supplies commercial power, the components for external power supply (isolation transformer 41, ground fault detection unit 42, alarm 43), and the changeover switch 21 for switching the power source can all be consolidated on the same wall 55. This makes it easier to construct this power supply system.

[0051] The present invention is not limited to the embodiments described above, and may be implemented, for example, as follows.

[0052] In the above embodiment, the electrical boxes 51 and 52 were attached to the wall 55 on which the distribution board 11 is mounted, but at least one of the electrical boxes 51 and 52 may be attached to a wall other than the wall 55.

[0053] In the above embodiment, the electrical boxes 51 and 52 were attached to the wall 55 of the living space 56, but the electrical box 52, which houses the isolation transformer 41, may be attached to the wall of a non-living space such as a storage room. In that case, the electrical box 52 may be formed with a depth dimension that can accommodate the entire isolation transformer 41. This would eliminate the need to have part of the isolation transformer 41 protrude into the wall. Furthermore, even if the electrical box 52 is enlarged in this way, the design of the interior will not be compromised because the electrical box 52 is located in a non-living space that is less visible to people.

[0054] In the above embodiment, a plug-in hybrid vehicle (PHV) was used as the external power supply device, but other vehicles such as electric vehicles (EVs) or fuel cell combined vehicles (FCHVs) may also be used as the external power supply device. Furthermore, it is not necessary to use a vehicle as the external power supply device; for example, a generator may be used. In that case, the generator and the building 10 are connected via a power supply cable, and the power generated by the generator is supplied to the building 10 side via the power supply cable while the connection is made. [Explanation of Symbols]

[0055] 10...Building, 11...Distribution board, 16-18...Electrical equipment, 21...Changeover switch as a changeover operation unit, 22...Power supply path as a commercial power supply path, 23...Automobile as an external power supply device, 27...Power supply cable, 31...Inlet as a connection part, 41...Isolation transformer, 42...Ground fault detection unit, 43...Alarm as a notification unit, 51...Electrical box as the first electrical box, 52...Electrical box as the second electrical box, 55...Wall section, 56...Living space.

Claims

1. A distribution board that receives commercial power from the commercial power source, A commercial power supply path for supplying the commercial power from the distribution board to electrical equipment within the building, An external power supply unit installed outdoors is connected to a connection point via a power supply cable, An external power supply path for supplying power from the external power supply device, which is supplied to the connection part via the power supply cable, to the electrical equipment from the connection part, A switching operation unit connected to the commercial power supply path and the external power supply path respectively, which of the commercial power and the power from the external power supply device is supplied to the electrical equipment, A power supply system for a building, comprising: An isolation transformer provided in the aforementioned external power supply path, A grounding path that grounds the primary side of the isolation transformer in the external power supply path, A ground fault detection unit that detects the ground fault current flowing through the grounding path when a ground fault occurs in the power supply cable, A notification unit that notifies of the occurrence of a ground fault when a ground fault current is detected by the ground fault detection unit, A first electrical equipment box housing the ground fault detection unit, the notification unit, and the switching operation unit, The second electrical box housing the aforementioned isolation transformer, Equipped with, A wall is provided facing the living space. The aforementioned wall section is composed of a plurality of wall panels arranged side by side, The distribution board, the first electrical box, and the second electrical box are all mounted on the same wall panel. The first electrical box and the second electrical box are located below the distribution board and are arranged side by side in the width direction of the wall, in a building power supply system.

2. The building power supply system according to Claim 1, wherein the isolation transformer is housed in the second electrical box with a portion of it protruding into the wall portion.

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