JP5030824B2 - Underground low-voltage wiring method - Google Patents

Description

  The present invention provides a low-voltage lead-in wire from a low-voltage trunk line disposed in the underground space such as a joint groove based on the Special Measures Law concerning maintenance of joint grooves, a wire joint groove based on the Special Measures Law concerning maintenance of wire joint grooves, etc. Underground and low-voltage line wiring for drawing a low-voltage lead-in line into a building through a lead-in path formed on at least one of a pair of wall surfaces that demarcate each other and define an underground space Regarding the method.

  Until now, power was supplied to each building by drawing a low-voltage service line branched from the low-voltage main line built on the utility pole into the building. However, the utility pole, low-voltage main line, low-voltage service line, etc. could harm the landscape or construct buildings. As a result, the special measures law concerning the maintenance of joint grooves, etc. and the special measures law concerning the maintenance of wire joint grooves, etc. are carried out, such as joint grooves and wire joint grooves based on these laws. Underground construction is progressing in which a low-voltage trunk line is disposed in the underground space, and a low-voltage lead-in line branched from the low-pressure trunk line is drawn into each building.

  The underground space is formed by various construction methods, for example, a plurality of insertion conduits intermittently arranged in the longitudinal direction so as to insert a low-pressure trunk line, and a box-shaped branch connecting the insertion conduits There are those that are buried in the ground and formed by the internal space of the insertion pipe and the branch fence (for example, see Patent Document 1), those that are formed by the tunnel constructed in the ground, etc. In this case, regardless of the form of the underground space, at least one of a pair of wall surfaces that divide the low-voltage lead-in line from the low-pressure trunk line disposed in the underground space and define the underground space facing each other. A low-voltage lead-in wire is inserted through a lead-in path formed on the wall surface side of the wall and drawn into the building.

As described above, various methods have been proposed as a method of branching the low-pressure lead line from the low-pressure main line. Generally, as shown in FIG. B is branched. That is, after the conductor exposed by removing the coating of the low-voltage lead-in wire B is aligned with the conductor exposed by partially removing the coating of the low-voltage trunk line A, the compression sleeve 60 fitted on both conductors The low-voltage main line A and the low-voltage service line B are electrically connected to each other, and the low-voltage service line B is branched from the low-voltage main line A (see, for example, Patent Documents 2 and 3).
JP 2002-17030 A JP 2001-325999 A JP 2001-326000 A

  However, when the low-pressure main line A and the low-pressure lead line B are connected by the compression sleeve 60 and the low-pressure lead line B is branched from the low-pressure main line A, there is a problem that the low-pressure lead line B excessively occupies the underground space.

  That is, when the low pressure lead line B is connected to the low pressure main line A using the compression sleeve 60 as described above, the low pressure lead line B is branched in a posture along the low pressure main line A, but the low pressure lead line B is difficult to bend. Therefore, when guiding the low-voltage lead-in line B to the one wall surface (building) side where the lead-in path is formed, the low-voltage lead-in line B is bent in a manner greatly curved along a virtual plane (not shown) along the axis of the low-voltage main line A. To the lower side of the underground space and then led to one wall side in a curved manner along another virtual plane (not shown) that intersects the virtual plane. There was a problem that the low-voltage lead-in wire B occupied a certain underground space excessively. For this reason, there is a case where a work space for adding the low-voltage lead-in line B to the underground space or removing the low-voltage lead-in line B cannot be secured.

  In addition, since the low-voltage lead-in wire B is heavy, the work of arranging the low-voltage lead-in wire B so as to be bent as described above has a problem that it places a heavy burden on the operator.

  Further, when the compression sleeve 60 directly branches the low-pressure lead line B to the low-pressure trunk line A, when the plurality of low-pressure lead lines B are branched from the single low-pressure trunk line A, the necessary interval in the axial direction of the low-pressure trunk line A is increased. The branch position of the low-voltage lead-in line B must be set open, and when the low-voltage lead-in line B is branched in a limited underground space such as a branch fence, the number of low-voltage lead-in lines B that can be drawn into the building is limited. There is also a problem that is added.

  Therefore, in view of such a situation, the present invention can branch the required number of low-voltage service lines in a limited amount of underground space without unnecessarily occupying the underground space. It is another object of the present invention to provide an underground low-voltage line wiring method that can reduce the work burden related to the wiring of the low-voltage lead-in line for the operator.

The underground low-voltage line wiring method according to the present invention branches at least one of a pair of wall surfaces that divide a low-voltage lead-in line from a low-voltage trunk line arranged in the underground space and define the underground space facing each other. An underground underground low-voltage line wiring method for inserting a low-voltage lead-in line into a lead-in path formed on the wall surface of the cable and drawing it into a building, which can be directly or indirectly electrically connected to the low-voltage main line When being insertable constructed more low pressure drop line in the same direction, respectively, the branching device having a plurality of drop cable connection port inserted low pressure drop cable is electrically connected to the mains connections, the incoming line connection port Branch device placement process to place and fix on the other wall side facing down, main line connection process to electrically connect the main line connection part to the low voltage main line, and main line connection by inserting the low voltage service line into the service line connection port Electric power Characterized in that it comprises a drop cable connection step of connecting, the pull step of inserting a low pressure drop cable to pull the path.

  According to the above-described underground low-voltage line wiring method, in the branching device arranging step, the branching device is provided on the other wall surface side facing the one wall surface where the low-voltage lead-in wire is drawn into the building so that the lead-in connection port faces downward. Since it is arranged and fixed, in the lead-in wire connection process, when a low-voltage lead-in wire is inserted into the lead-in wire connection port and electrically connected, the low-voltage lead-in wire separates from the branch device on the other wall side that defines the underground space. It becomes a drooping aspect. And in the drawing-in process, since the low-voltage lead-in wire is inserted through the lead-in route on the one wall surface side and drawn from the underground space to the building side, the low-voltage lead-in wire connected to the branch device is drooping from the branch device. Then, it is drawn into the building in a state bent to one wall surface side.

  As a result, the low-voltage lead-in wire that is heavy and difficult to bend can be disposed in the underground space with the minimum required bending (for example, by bending it into an arc shape having a large radius of curvature). Can be reduced. In addition, since the low-voltage service line is suspended from the low-voltage trunk line as described above, the low-voltage service line is not randomly arranged as in the prior art, and the occupation rate of the low-voltage service line with respect to the underground space can be reduced. . Thereby, the work space which adds a low voltage | pressure lead wire with respect to limited underground space, or removes a low voltage | pressure lead wire can also be ensured.

  Furthermore, by adopting a branching device having a plurality of service line connection ports as described above, it is not necessary to branch the low voltage service line from multiple locations on the low voltage trunk line, and the number required in a limited underground space Can be branched.

  As one aspect of the present invention, the trunk connection portion of the branching device is electrically connected to each service line connection port, and sandwiched between the low-voltage trunk lines so as to be electrically connected to the low-voltage trunk lines. In the main line connecting step, the low-voltage main line may be sandwiched between a pair of holding bodies to be electrically connected. If it does in this way, it can electrically connect with respect to a low voltage | pressure trunk line only by pinching | interposing the conductor exposed by removing the coating | cover of a low voltage | pressure main line with a pair of clamping body.

  As another aspect of the present invention, the main line connecting portion of the branch device is configured to be electrically connectable by inserting a branch conductor branched from the terminal of the low voltage main line or the low voltage main line. You may make it electrically connect by inserting a termination | terminus part or a branch conductor in a trunk line connection part. If it does in this way, in a branch device arrangement process, a branch device can be made into desired arrangement by using a branch conductor of a form (length or shape) corresponding to arrangement of a branch device.

  As another aspect of the present invention, in the branching device arrangement step, the branching device may be fixed to a frame erected along the other wall surface. In this way, the branching device can be maintained in a desired arrangement without performing any special work.

  As a specific aspect of the present invention, the branching device arrangement step includes a step of arranging the low-pressure trunk line when two or more branching apparatuses corresponding to each of the two or more low-voltage trunk lines arranged in parallel between the hollow spaces are viewed from above. It is preferable that the main line connecting step is arranged so that the main line connecting portions of the branching apparatus corresponding to each low-voltage main line are electrically connected to each low-voltage main line. In this way, the low-voltage service line that is connected to the service line connection port and is in a suspended state is guided to one wall surface side without interfering with the branch device connected to the other low-voltage main line or the low-voltage service line connected thereto. Can do. In addition to the above arrangement, each branch device may be arranged at a position shifted in the axial direction of the low-voltage trunk line. In this way, it is possible to reliably suppress interference between the low-voltage lead wires that are suspended from each branch device and guided to one wall surface side.

  According to the underground low-voltage line wiring method according to the present invention, the low-voltage lead-in line does not unnecessarily occupy the underground space, and the necessary number of low-voltage lead-in lines are branched in the limited underground space. In addition, it is possible to achieve an excellent effect of reducing the work load related to the wiring of the low-voltage lead-in wire for the worker.

  Hereinafter, an underground low-voltage line wiring method (hereinafter simply referred to as a wiring method) according to a first embodiment of the present invention will be described with reference to the accompanying drawings.

  First, the underground low-voltage line, the branching device used in the wiring method, and the frame, which are the premise of the wiring method according to the present embodiment, will be described. As shown in FIG. Low-voltage trunk lines A1, A2, A3, A4 disposed in underground space T such as a common groove, and low-voltage lead lines B1, B2, B3 branched from low-voltage trunk lines A1, A2, A3, A4 and drawn into building S , B4.

  The low-voltage trunk lines A1, A2, A3, and A4 include a ground line A1, a light line A2, a common line A3, and a power line A4. These four lines are arranged in the underground space T as a set. The cable diameters of the ground wire A1, the power line A2, the common line A3, and the power line A4 are set according to their roles. Generally, the ground line A1 and the power line A4 are 150 sq, the power line A2 and The shared line A3 is set to 250 sq.

  The low-voltage lead-in lines B1, B2, B3, B4 are branched from the low-voltage trunk lines A1, A2, A3, A4, and face one side of the pair of wall surfaces Wa, Wb that define the underground space T facing each other. Is inserted into the building S from the underground space T as the ground line B1, the power line B4, the lamp line B2, and the common line B3. Note that the number of the low-voltage lead-in wires B1, B2, B3, and B4 that are drawn into the building S depending on the contract between the customer and the electric power company is four or less (for example, two that are shared with the earth, or two that are the earth and the lamp) , Earth, power, three lights, and earth, common, three lights, power, etc.).

  The branch device 1 is for branching the low-voltage service lines B1, B2, B3, B4 from the low-voltage trunk lines A1, A2, A3, A4, and is arranged for each of the low-voltage trunk lines A1, A2, A3, A4. As shown in FIGS. 2 to 4, the branch device 1 includes a main line connection portion 10 that can be directly or indirectly electrically connected to the low-voltage main lines A1, A2, A3, and A4, and the low-voltage lead lines B1 and B2. , B3, B4 can be inserted from the same direction, and the inserted low-voltage service lines B1, B2, B3, B4 are provided with a plurality of service line connection ports 200 to be electrically connected to the main line connection part 10. .

  More specifically, the branch device 1 used in the wiring method of the present embodiment includes a main line connection unit 10 and a device main body 20 in which the plurality of service line connection ports 200 are formed.

  As shown in FIGS. 2 and 3, the main line connecting portion 10 according to the present embodiment is configured to sandwich the exposed conductor from both sides in the radial direction by removing the covering of the low-voltage main lines A1, A2, A3, A4. A pair of sandwiching bodies 10a, 10b is provided. Each of the pair of sandwiching bodies 10a and 10b includes a conductive sandwiching body main body 100a and 100b extending in one direction and having a cross-sectional shape viewed from the one direction formed in an arc shape, and the sandwiching body main bodies 100a and 100b. A pair of flange portions 101a and 101b extending outward from both side end portions extending in one direction are provided, and the respective sandwiching body bodies 100a and 100b sandwich the conductor by fastening the flange portions 101a and 101b to each other. It is configured to be in a state.

  The apparatus main body 20 is formed with a plurality of service line connection ports 200 through which low-voltage service lines B1, B2, B3, B4 can be inserted, and the inserted low-voltage service lines B1, B2, B3, B4 are connected to the main line connection part 10. It is designed to be connected electrically. Specifically, as shown in FIG. 3, the apparatus main body 20 includes a casing 210 made of an insulating material, a conductive member 220 built in the casing 210, a casing 210, and the lead-in wire connection port 200. Are provided with a lead-in wire fixing means 230 for fixing the low-voltage lead-in wires B1, B2, B3, and B4 inserted into the conductive member 220, and a sealing member 240 for sealing the lead-in wire connection ports 200 in a liquid-tight manner. .

  The casing 210 according to the present embodiment is a resin molded product, and includes a casing body 211 in which an opening is formed on one surface and the conductive member 220 is internally provided, and a closing member 215 that closes the opening of the casing body 211. Yes.

  The casing main body 211 has an open substantially entire area on one surface, and is protruded from a box-shaped main body accommodating portion 211a in which a conductive member main body 221 (described later) of the conductive member 220 is accommodated, and a wall portion facing the opening of the main body accommodating portion 211a. And a cylindrical housing portion 211b in which a connecting conductive portion 222 (described later) of the conductive member 220 is housed.

  As shown in FIG. 4, the main body accommodating portion 211a is formed in a horizontally long shape so that the opening is substantially rectangular. The main body accommodating portion 211a is provided with protruding pieces 211c projecting outward at one end of a longitudinal wall portion that defines an opening. The convex piece 211c has a hole (not numbered) for inserting a bolt. As shown in FIG. 3, an operation portion 212 is formed on the other side of the long wall defining the opening of the main body housing portion 211 a so that the lead-in wire fixing means 230 can be accessed from the outside. Since the apparatus main body 20 according to the present embodiment has a plurality of service line connection ports 200 as described above, a plurality of operation units 212 are also formed side by side corresponding to each service line connection port 200 ( (See FIG. 2).

  Each operation part 212 includes a cylindrical part 212a protruding from the outer surface of the wall part, and a lid part 212b capable of opening and closing the opening of the cylindrical part 212a. The tubular portion 212a is formed integrally with the casing body 211 so that the inside (inner hole) communicates with the inside of the body housing portion 211a. A part of the lid portion 212b is hinged to the outer surface of the cylindrical portion 212a so that the opening of the cylindrical portion 212a can be opened and closed. The lid portion 212b is provided with a packing 212c on the inner surface, and in a state where the opening of the cylindrical portion 212a is closed, the packing 212c is in pressure contact with the upper end surface of the cylindrical portion 212a. It is supposed to become. And in order to maintain the cover part 212b in this liquid-tight state, in this embodiment, while the latching claw 212d is protrudingly provided in the position opposite to the butterfly position with respect to the cylindrical part 212a in the cover part 212b, The locked portion 212e is projected on the outer surface of the cylindrical portion 212a, and the locking claw 212d is locked to the locked portion 212e in a state where the upper end opening of the cylindrical portion 212a is closed by the lid portion 212b. It is like that.

  The cylindrical housing portion 211b is formed integrally with the main body housing portion 211a so that the inside communicates with the inside of the main body housing portion 211a. The cylindrical housing part 211b according to the present embodiment is formed at a substantially central position in the longitudinal direction of the main body housing part 211a.

  As shown in FIGS. 3 and 4, the casing 210 according to the present embodiment is configured to close the opening by fitting a closing member 215 into the opening of the main body housing portion 211 a. The closing member 215 includes a plate-like base portion 216 that is fitted into the opening of the main body housing portion 211a, and a cylindrical lead-in wire connection port 200 that protrudes from one surface of the base portion 216. ing. The base portion 216 is formed corresponding to the shape (rectangular shape) of the opening of the main body accommodating portion 211a, and has a through-hole (not numbered) corresponding to the arrangement of the lead-in wire connection ports 200. A plurality of the lead-in connection ports 200 are provided at intervals in the longitudinal direction of the closing member 215. The inside of the lead-in wire connection port 200... Communicates with the hole of the base portion 216. Accordingly, the closing member 215 penetrates through the front and back through the hole of the base portion 216 and the inner hole of the lead-in connection port 200.

  The conductive member 220 is made of a conductive metal material, and includes a conductive member main body 221 formed in a block shape and the connecting conductive portion 222 projecting from the outer surface of the conductive member main body 221. Yes.

  The conductive member main body 221 is set so that the outer dimension corresponds to the inner dimension of the casing main body 211, and the conductive member main body 221 is fitted into the casing main body 211 in a state where the outer surface substantially contacts the inner surface of the casing main body 211. ing. The conductive member main body 221 is set so that one surface on the opening side of the main body housing portion 211a is recessed from the opening end of the main body housing portion 211a by a predetermined amount in a state of being fitted into the casing main body 211. Has been. That is, in a state in which the closing member 215 is attached to the casing main body 211, a space for accommodating a predetermined amount of gap (an opening sealing portion 241 described later of the sealing member 240) between the inner surface of the closing member 215 (base portion 216). ) Is formed.

  Further, a plurality of conductor insertion holes 223 for inserting the conductors of the low-voltage lead wires B1, B2, B3, B4 are formed in the conductive member body 221 at intervals in the longitudinal direction (see FIG. 4). . That is, the conductive member main body 221 has a plurality of conductor insertion holes 223 formed so as to be substantially concentric with the lead-in connection ports 200 of the closing member 215 that closes the opening of the main body accommodating portion 211a. Further, as shown in FIG. 3, the conductive member main body 221 has a screw hole 224 that is substantially concentric with the operation portion 212 of the casing main body 211 in a state where the conductive member main body 221 is fitted in the casing main body 211, and the conductor insertion holes 223. It is formed to penetrate. That is, screw holes 224 extending in a direction substantially orthogonal to the conductor insertion holes 223... Are formed in a surface facing the wall portion of the casing body 211 where the operation portion 212 is formed. Further, the conductive member main body 221 is provided in the inner periphery of the conductor insertion holes 223... So that a recess 225 for accommodating a fixing member 232 described later of the lead-in wire fixing means 230 includes the opening of the screw hole 224. . The recess 225 is set to a depth that can completely accommodate the fixing member 232.

  The connection conductive portion 222 includes a substantially cylindrical connection main body portion 222a having a base end connected to the conductive member main body 221, and a connection extending to a distal end of the connection main body portion 222a and connected to the main line connection portion 10. Part 222b. The connection main body portion 222 a is formed integrally with the conductive member main body 221, and is inserted into the cylindrical housing portion 211 b of the casing main body 211. That is, the conductive member 220 is fitted into the casing main body 211 with the connecting main body portion 222a at the top, so that the connecting main body portion 222a is accommodated in the cylindrical accommodating portion 211b and the conductive member main body 221 is accommodated in the main body. It is accommodated in the part 211a.

  The connecting portion 222b is formed in a plate shape, and one end is connected to the tip of the connecting conductive portion 222. The connecting portion 222b is formed integrally with the connecting main body portion 222a. In the present embodiment, the connecting portion 222b is provided along the parallel direction of the conductor insertion holes 223 (lead wire connection ports 200). And although this connection part 222b is connected with the trunk line connection part 10, in this embodiment, it is connected using the fastening means (bolt and nut) which fastens a pair of clamping body 10a, 10b. It has become. That is, the connecting portion 222b is formed with a through hole (not numbered) through which the bolt of the fastening means is inserted, and is penetrated after being overlapped with the flange portions 101a and 101b of the holding bodies 10a and 10b. Bolts are inserted into the holes and nuts are screwed into the bolts so that the main line connecting portion 10 is connected to the conductors of the low-voltage main lines A1, A2, A3, and A4.

  The lead-in wire fixing means 230 according to this embodiment includes a push screw 231 that is screwed into the screw hole 224 of the conductive member main body 221 and a fixing member 232 that is attached to the tip of the push screw 231. The push screw 231 has a rod-shaped male screw portion 231a continuously provided on a head operable by a tool, and a pin portion 231b having a smaller diameter than that of the male screw portion 231a is provided continuously at the tip of the male screw portion 231a. Has been. The push screw 231 has the head located in the operation unit 212 with the upper end opening of the cylindrical part 212a closed by the lid part 212b, and the tip of the pin part 231b retracted from the conductor insertion hole 223. The length is set so as to be in a state (a state positioned in the recess 225). Thus, the push screw 231 is configured such that the distal end side thereof can be withdrawn / retracted from the conductor insertion holes 223... By operating the head.

  The fixing member 232 is formed by bending a metal piece into a U-shape, and a pair of pressing pieces 232a and 232a facing each other with a gap therebetween, and base ends of the pair of pressing pieces 232a and 232a are connected to each other. And a connected connecting piece 232b. The connecting piece 232b is formed with a hole (not numbered) for inserting the pin portion 231b. As a result, the connecting piece 232b can be inserted in a state where the tip end portion (pin portion 231b) of the push screw 231 is interposed between the pair of pressing pieces 232a and 232a. The distal end portion of the push screw 231 is prevented from being detached from the fixing member 232. In this embodiment, the distal ends of the pair of pressing pieces 232a and 232a and the distal end of the pin portion 231b are at substantially the same level. It is prevented from coming off (located on the same surface). As a result, the lead-in wire fixing means 230 according to this embodiment is configured such that the conductors of the low-voltage lead wires B1, B2, B3, and B4 are spaced apart in the axial direction by the three of the pair of pressing pieces 232a and 232a and the tip of the pressing screw 231. It can be pressed.

  As a result, the conductors of the low-voltage lead-in wires B1, B2, B3, B4 are inserted into the conductor insertion holes 223 of the conductive member 220 in the lead-in connection ports 200. By being pressed, the conductor is brought into close contact with the inner peripheral surfaces of the lead-in wire fixing means 230 and the conductor insertion holes 223... And is electrically connected to the main line connecting portion 10 via the conductive member 220.

  The sealing member 240 is formed by molding a gel material, and as shown in FIGS. 3 and 4, the opening sealing portion 241 formed in a substantially rectangular plate shape corresponding to the shape of the opening of the main body housing portion 211a. And a cylindrical lead-in wire connection port sealing portion 242... Extending from one surface of the opening sealing portion 241. The gel material constituting the sealing member 240 may be any material as long as the low-voltage lead-in wires B1, B2, B3, and B4 can be stabbed and elastically deformable (highly recoverable). In view of properties such as property, it is preferable to employ a silincon gel material.

  The opening sealing portion 241 is interposed between the conductive member 220 (conductive member main body 221) fitted in the casing main body 211 and the closing member 215 (base portion 216). The thickness is close to the conductive member main body 221 and the base portion 216 of the closing member 215 in a state where the opening of the portion 211a is closed. In this embodiment, the opening sealing portion 241 is set to a thickness that is sandwiched between the conductive member main body 221 and the closing member 215 and elastically deformed, and can seal the space between the casing main body 211 and the closing member 215 in a liquid-tight manner. It is like that.

  The lead-in wire connection port sealing portions 242... Are integrally formed with the opening sealing portion 241. The lead-in connection port sealing portions 242 are press-fitted into the lead-in connection ports 200 of the closing member 215, and a plurality of the lead-in connection port sealing portions 242 are provided corresponding to the arrangement of the lead-in connection ports 200 of the closing member 215. The sealing member 240 (opening sealing portion 241 and lead-in connection port sealing portion 242...) Seals the lead-in connection port until the low-voltage lead-in wires B1, B2, B3, B4 are inserted into the lead-in connection ports 200. The portions 242 are filled in the lead-in wire connection port 200 and are in close contact with the inner peripheral surface of the lead-in wire connection port 200 so that the inside of the casing 210 is maintained in a liquid-tight state. Further, when the low-voltage lead wires B1, B2, B3, B4 are inserted into the lead-in wire connection ports 200, the low-voltage lead wires B1, B2, B3, B4 strike the lead-in wire connection port sealing portion 242 ... and the opening sealing portion 241. And the space between the outer periphery of the low-voltage lead-in wires B1, B2, B3, B4 and the inner periphery of the lead-in wire connection port 200 ... is filled, and the inner peripheral surface of the lead-in wire connection port 200 ... and the low-voltage lead-in wires B1, B2, In close contact with the outer peripheral surfaces of B3 and B4, the inside of the casing 210 is maintained in a liquid-tight state.

  Since branching device 1 concerning this embodiment has the main line connection part 10 attached to low voltage main line A1, A2, A3, A4, since the outer surface of conductive main line connection part 10 is exposed, it aims at the waterproofing of the part. Therefore, the waterproof cover 30 shown in FIG. 5 is provided.

  The waterproof cover 30 includes a cover main body 300 formed of an insulating material (resin material), and a sealing member 310 provided in the cover main body 300. The cover main body 300 is composed of a pair of upper and lower divided covers 300a and 300b, and is configured so as to be substantially box-shaped as a whole by combining them.

  The cover main body 300 has a pair of upper and lower divided covers 300a and 300b, so that holes 301 and 302 through which the low-voltage trunk lines A1, A2, A3, and A4 are inserted are formed in a pair of opposed walls. A hole 303 through which the cylindrical accommodating portion 211b of the branching device 1 is inserted is formed in another wall portion to which the other wall portion is connected. That is, each of the divided covers 300a and 300b has substantially semicircular concave portions 301a, 301b, 302a, 302b, 303a, and 303b formed in the portion that becomes the wall portion, and the concave portions 301a, 301b, 302a, 302b, 303a, and 303b become one hole 301, 302, and 303.

  In the present embodiment, the pair of divided covers 300a and 300b are hinged on the wall surface facing the wall surface forming the hole 303 through which the cylindrical housing portion 211b is inserted, and can be opened and closed. Further, one split cover 300a, 300b has an engaging claw 304 protruding from a wall portion that forms a hole 303 through which the cylindrical housing portion 211b is inserted, and is engaged with a wall portion of the other split cover 300a, 300b. An engaged portion 305 for engaging the claw 304 is provided in a protruding manner. As a result, by engaging the engaging claw 303 with the engaged portion 304, the pair of divided covers 300a and 300b can be maintained in an integrated state.

  The sealing member 310 is made of, for example, a silicon-based gel material, and is filled in the divided covers 300a and 300b. And as above-mentioned, the sealing member 310 (gel material) in each division | segmentation cover 300a, 300b comes to closely_contact | adhere by combining a pair of division | segmentation cover 300a, 300b. Accordingly, the waterproof cover 30 is configured such that the main line connection portion 10 attached to the low-voltage main lines A1, A2, A3, and A4 is sandwiched between the divided covers 300a and 300b, so that the outer surface of the main line connection portion 10 and one of the cylindrical housing portions 211b. The sealing member 310 (gel material) is in intimate contact with the outer surface of the portion, so that the conductive main line connecting portion 10, the connecting portion 222b, and the like can be liquid-tightly covered.

  Next, the frame will be described. As shown in FIGS. 6A and 6B, the frame is formed by combining steel materials such as shaped steel, and at least a pair of legs standing up and down. 400 and 400, and beam members 401 connecting the leg members 400 and 400 to each other. In the frame 40, the leg members 400 are fixed to the wall surface defining the underground space T by anchor bolts, and the branch device 1 is attached to the beam member 401.

  And in this embodiment, since the separate branch apparatus 1 is electrically connected to each of the four low-voltage trunk lines A1, A2, A3, A4, the beam members 401 to which the branch apparatus 1 is attached. Are provided at intervals in the vertical direction. Each of the beam members 401 is attached to the branch device 1 on the front surface, and the upper or lower beam member 401 with respect to the lower or upper beam member 401 is separated from the legs 400 and 400. It is arranged to be in the position. Therefore, both ends of the beam member 401 at a position separated from the leg member 400 are fixed to the arms 402 extending forward from the respective leg members 400. Thus, the frame 40 is arranged in a state where the branching device 1 is displaced from each other in a direction perpendicular to the longitudinal direction of the beam members 401 when viewed from above, with the branching device 1 fixed to each beam member 401. It has come to be.

  And the frame 40 which concerns on this embodiment is set to the position where the attachment position of the branching apparatus 1 with respect to each beam material 401 ... shifted | deviated to the longitudinal direction of the beam material 401 .... In each beam member 401..., Bolt holes 403... Corresponding to the holes of the convex pieces 211 c of the branch device 1 (casing 210) are formed for each mounting position of the branch device 1.

  Thus, in the frame 40, when the both leg members 400, 400 are arranged along the wall surface of the underground space T, each beam member 401 ... extends in the same direction as the low-voltage trunk lines A1, A2, A3, A4. The branching devices 1 fixed to the beam members 401 are displaced from each other in a direction perpendicular to the axis of the low-voltage trunk lines A1, A2, A3, A4 when viewed from above, and the low-voltage trunk lines A1, A2, A3 , A4 are arranged so as to be arranged at positions shifted from each other in the axial direction of A4.

  Next, the underground low-voltage line wiring method according to the present embodiment will be described. First, of a pair of opposing wall surfaces Wa and Wb that define the underground space T, a wall surface (one wall surface) on which a drawing path R for drawing the low-voltage lead wires B1, B2, B3, and B4 into the building S is formed. The said frame 40 is arrange | positioned at the wall surface (other wall surface) Wb side opposite to Wa (refer FIG. 9). At this time, in the frame 40, the two leg members 400, 400 are arranged along the other wall surface Wb so that each beam member 401 is positioned on the one wall surface Wa side, and each leg member 400, 400 is arranged. Is fixed to the wall surface Wb via an anchor bolt.

  Then, as shown in FIG. 7A, the branching device 1 is arranged and fixed to the frame 40 so that the lead-in connection ports 200... Face downward (branching device arranging step), and the insulation coating is partially applied beforehand. The conductors of the low-voltage trunk lines A1, A2, A3, and A4 exposed by the removal are sandwiched between the pair of sandwiching bodies 10a and 10b, and the trunk connection section 10 is electrically connected to the low-voltage trunk lines A1, A2, A3, and A4 (the trunk line Connection process). Thereafter, as shown in FIG. 7B, the waterproof connection 30 covers a part of the main line connecting portion 10 and the tip side of the cylindrical housing portion 211b in a liquid-tight manner.

  Then, the branch device 1 corresponding to the other low-voltage trunk lines (earth line A1, lamp line A2, common line A3, power line A4) that need to branch the low-voltage lead-in lines B1, B2, B3, B4 in the above-described procedure. While being fixed to the frame 40, the main line connection portion 10 is electrically connected to the corresponding low-voltage main lines A1, A2, A3, A4 (branch device arrangement process, main line connection process). When a plurality of (two or more) branching devices 1 are fixed to the frame 40 in this way, each branching device 1 corresponds to a plurality of beam members 401 (attachment positions of the branching device 1) provided on the frame 40. When viewed from above, they are displaced from each other in the direction perpendicular to the axis of the low-voltage trunk lines A1, A2, A3, A4, and are also arranged at positions shifted from each other in the longitudinal direction of the low-voltage trunk lines A1, A2, A3, A4. .

  The arrangement of the branch device 1 (branch device arrangement process) and the connection of the main line connection unit 10 to the low-voltage main lines A1, A2, A3, A4 (main line connection process) may be performed first. Further, any of the insulation coating removal of the low-voltage trunk lines A1, A2, A3, and A4 and the arrangement of the frame 40 may be performed first. However, when the frame 40 is made of metal and the low-voltage main lines A1, A2, A3, and A4 are energized as in the present embodiment, the conductor is in contact with the frame 40 when the frame 40 is transported. Considering the existence of danger, it is preferable to remove the insulation coating on the low-voltage trunk lines A1, A2, A3, A4 after the frame 40 is arranged or fixed as described above.

  Then, in order to branch the low-voltage service lines B1, B2, B3, and B4 from the low-voltage trunk lines A1, A2, A3, and A4, as shown in FIG. 8, the insulation coating at the ends of the low-voltage service lines B1, B2, B3, and B4 is removed. Then, after exposing the conductor, the conductor is inserted into one of the lead-in connection ports 200. Then, the low-voltage lead wires B1, B2, B3, and B4 are pierced with respect to the lead wire connection port sealing portions 242... And the opening sealing portion 241, and finally the conductor insertion formed substantially concentric with the lead wire connection ports 200. The conductor reaches the holes 223. In this state, the inside is kept in a liquid-tight state by the sealing member 310 (gel) between the insulating coating or conductor of the low-voltage lead wires B1, B2, B3, B4 and the inner peripheral surface of the lead wire connection port 200. become.

  Thereafter, the lead-in wire fixing means 230 fixes the low-voltage lead wires B1, B2, B3, and B4 to the branch device 1 in conjunction with the electrical connection between the low-voltage lead wires B1, B2, B3, and B4 and the main line connecting portion 10 (lead wire). Connection process). Then, by closing the lid 212b of the operation unit 212, the inside is completely liquid-tight, and even if rainwater or the like flows into the underground space T and is submerged, reliable waterproofing can be achieved. become.

  Then, as shown in FIG. 9, the low-voltage lead lines B1, B2, B3, and B4 branched from the low-voltage trunk lines A1, A2, A3, and A4 are inserted into the drawing route R formed on the one wall portion Wa side. The one end side of the low-voltage lead-in wires B1, B2, B3, B4 is positioned in the underground space T and the other end side is positioned in the building S (retraction process). This lead-in process may be performed after the low-voltage lead lines B1, B2, B3, and B4 are branched from the low-voltage trunk lines A1, A2, A3, and A4. However, it is more likely that the lead-in connection process is performed after performing the lead-in process in advance. Since there is no low-voltage lead-in line B1, B2, B3, B4 or the like that has been pulled into the underground space T in the connection process, the work space can be effectively secured.

  In any case, since the low-voltage service lines B1, B2, B3, and B4 are inserted and connected to the service line connection ports 200 that are directed downward as described above, the low-voltage service lines B1 and B2 fixed to the branch device 1 are connected. , B3, B4 are guided from the branching device 1 (the lead-in connection port 200) to the lead-in route R on the one wall surface Wa side while being largely curved. Therefore, the low-voltage lead-in wires B1, B2, B3, B4 are merely curved at one location, and are not bent unnecessarily in the axial direction of the low-voltage trunk lines A1, A2, A3, A4. Working space can be secured. In addition, since the low-voltage service lines B1, B2, B3, and B4 can be arranged in this manner, the operation of detouring the low-voltage service lines B1, B2, B3, and B4 is not necessary. It is possible to reduce the work burden on the worker who installs B3 and B4.

  As described above, the underground low-voltage line wiring method according to the present embodiment has the main line connection part 10 that can be directly electrically connected to the low-voltage main lines A1, A2, A3, and A4, and the low-voltage lead lines B1, B2, and B3. , B4 can be inserted, and each of the branching devices 1 including a plurality of service line connection ports 200, to which the inserted low-voltage service lines B1, B2, B3, B4 are electrically connected to the main line connection unit 10 is connected to each service line. A branching device arranging step for arranging the connecting port 200 on the other wall surface Wb side so as to face downward, a main line connecting step for electrically connecting the main line connecting portion 10 to the low voltage main lines A1, A2, A3, A4, and a low pressure A lead-in wire connecting step of inserting the lead-in wires B1, B2, B3, B4 into the lead-in wire connection ports 200 and electrically connecting to the main line connecting portion 10, and a low-voltage lead-in wire B1, B2, B3, B4 through the lead-in route R Hollow The low-voltage lead-in wires B1, B2, B3, and B4 are suspended from the branching device 1 to the one wall surface Wa side on the bottom surface side that defines the underground space T. The low-voltage lead-in wires B1, B2, B3, and B4 that are heavy and difficult to bend are pulled into the building S in a bent state, and are minimally bent (for example, simply bent into an arc shape with a large radius of curvature). It can be arranged in the underground space T, and the work burden on the operator can be reduced.

  In addition, as described above, the low-voltage service lines B1, B2, B3, and B4 are suspended from the low-voltage trunk lines A1, A2, A3, and A4, so that the low-voltage service lines B1, B2, B3, and B4 need to be circumvented as in the past. Therefore, the occupation ratio of the low-voltage lead-in wires B1, B2, B3, and B4 with respect to the underground space T can be reduced. Thereby, it is also possible to secure a work space for adding the low-voltage lead-in wires B1, B2, B3, B4 to the limited underground space T and removing the low-voltage lead-in wires B1, B2, B3, B4.

  Further, by adopting the branching device 1 having a plurality of service line connection ports 200 as described above, the low voltage service lines B1, B2, B3, B4 are branched from a plurality of locations of the low voltage trunk lines A1, A2, A3, A4. There is no need, and the necessary number of low-voltage service lines B1, B2, B3, B4 can be branched in the underground space T of a limited size.

  Further, the branch device 1 is configured to be electrically connectable by sandwiching the low-voltage trunk lines A1, A2, A3, and A4, and a pair of sandwiching bodies 10a and 10b that are electrically connected to the service line connection ports 200. Are connected as the main line connecting part 10 and the main line connecting step is such that the low-voltage main lines A1, A2, A3, A4 are sandwiched and electrically connected by the pair of holding bodies 10a, 10b. The conductor exposed by removing the coverings of A3 and A4 can be electrically connected to the low-voltage trunk lines A1, A2, A3, and A4 simply by sandwiching the conductor between the pair of sandwiching bodies 10a and 10b.

  Further, since the branching device 1 is fixed to the frame 40 erected along the other wall surface Wb in the branching device arranging step, the arrangement of the branching device 1 can be maintained in an appropriate state. Moreover, the connection state of the low-voltage trunk lines A1, A2, A3, A4 and the low-voltage lead-in lines B1, B2, B3, B4 can be maintained in an appropriate state.

  And in a branching device arrangement | positioning process, low pressure seeing two or more branching devices 1 ... corresponding to each of two or more low voltage | pressure main lines A1, A2, A3, A4 arrange | positioned in parallel in the underground space T from upper direction. The main lines A1, A2, A3, A4 are shifted from each other in a direction perpendicular to the axis of the main lines A1, A2, A3, A4, and are displaced in the axial direction of the low-voltage main lines A1, A2, A3, A4. , A3, and A4, the main line connection portion 10 of the branching device 1 is electrically connected, so that the low-voltage service lines B1, B2, B3, and B4 that are connected to the service line connection port 200 and are suspended are connected to other services. Each of the low-voltage service lines B1, B2, B3, and B4 is connected to the branch device 1 connected to the low-voltage trunk lines B1, B2, B3, and B4 without interfering with the low-voltage service lines B1, B2, B3, and B4 connected thereto. It can be guided to the wall Wa side.

  Next, a wiring method according to the second embodiment of the present invention will be described.

  As in the first embodiment, the wiring method according to the present embodiment branches a low-voltage lead-in line from a low-voltage trunk line such as a ground line, an electric light line, a common line, and a power line that is disposed in the underground space as a low-voltage line. Since it is intended to be drawn into the building and the same frame as the first embodiment is adopted as the frame, the underground low voltage line and the frame are described with the same name and the same reference numerals as the first actual form Omit. Moreover, about the branch apparatus which concerns on this embodiment, suppose that the same name and the same code | symbol are attached | subjected about the structure similar to the structure of 1st embodiment, or an equivalent structure.

  As shown in FIGS. 10 to 12, the branch device 1 employed in the wiring method according to the present embodiment is directly or indirectly connected to the low-voltage trunk lines A1, A2, A3, and A4 as in the first embodiment. Are connected to the main line connecting portion 10 and the low-voltage lead-in wires B1, B2, B3, B4 from the same direction, and the inserted low-voltage lead-in wires B1, B2, B3, B4 are connected to the main line connecting portion 10. And a plurality of lead-in wire connection ports 200 that are electrically connected.

  The branch device 1 according to the present embodiment is configured in the same manner as the service line connection ports 200 for connecting the main line connection unit 10 to the low-voltage service lines B1, B2, B3, B4, and the plurality of service line connection ports 200 and the like. It is formed integrally with the main body 20. That is, the trunk line connecting portion 10 of the branching device 1 according to the present embodiment includes a branch conductor 50 (described later) branched from the terminal end of the low-voltage trunk lines A1, A2, A3, A4 or the low-voltage trunk lines A1, A2, A3, A4. 13 is inserted and is configured to be electrically connectable, and is formed side by side with the lead-in connection port 200 with respect to the apparatus main body 20 (hereinafter, the main line connection portion 10 is connected to the main line connection port in the present embodiment). Suppose).

  More specifically, as shown in FIGS. 11A and 11B, the apparatus main body 20 includes a casing 210 made of an insulating material, and a conductive member 220 built in the casing 210. The lead wire fixing means 230 for fixing the low-voltage lead wires B1, B2, B3, and B4 inserted into the lead wire connection ports 200 to the conductive member 220, and the casing 210, and the main wire connection port 10 A main line fixing means 250 for fixing the inserted low-voltage main lines A1, A2, A3, A4 to the conductive member 220, and a sealing member 240 for liquid-tightly sealing the main line connection port 10 and each of the lead-in line connection ports 200. I have.

  The casing 210 according to the present embodiment is a resin molded product, and as shown in FIGS. 10 and 12, a casing main body 211 that is formed in a box shape having an open substantially front surface and in which a conductive member 220 is provided, And a closing member 215 that closes the opening of the casing body 211.

  The casing main body 211 according to the present embodiment is formed in a horizontally long shape so that the opening is substantially rectangular, and a protruding piece 211c for fixing to the frame 40 is attached to one end of a long wall portion that defines the opening. It protrudes toward the direction. A hole (not numbered) for inserting a bolt is formed in the convex piece 211c. As shown in FIG. 10, the casing body 211 is formed with a service line operation portion 212 that is accessible from the outside to the service wire fixing means 230 on the other of the long walls defining the opening, and is fixed to the main line. A main line operation unit 270 is formed which can access the means 250 from the outside. Since the main body connection port 10 and the plurality of service line connection ports 200 are formed in the apparatus main body 20 according to the present embodiment as described above, corresponding to the main line connection port 10 and the plurality of service line connection ports 200. A single trunk line operation unit 270 and a plurality of service line operation units 212 are arranged side by side and in a row.

  As is clear from FIGS. 11A and 11B, the service line operation unit 212 and the main line operation unit 270 have the same configuration as the operation unit 212 of the first embodiment. The lead-in wire fixing means 230 and the main wire fixing means 250 provided corresponding to these may be in the same or similar relationship depending on the size of the target low-voltage line, but both are the lead-in wire fixing means 230 of the first embodiment. Therefore, the description here will be omitted with reference to the first embodiment.

  The casing 210 according to the present embodiment is configured to close the opening by fitting a closing member 215 into the opening of the casing body 211. As shown in FIG. 12, the closing member 215 includes a plate-like base portion 216 fitted into the opening of the casing body 211 and a plurality of lead-in wires having a cylindrical shape protruding from one surface of the base portion 216. Similar to the connection port 200... And the lead-in connection port 200..., A cylindrical main line connection port 10 that is provided on one surface of the base portion 216 is provided. The base portion 216 is formed corresponding to the shape (rectangular shape) of the opening of the main body accommodating portion 211a, and has a hole (not numbered) penetrating therethrough corresponding to the arrangement of the lead-in connection port 200. Is formed. The plurality of service line connection ports 200 are provided in a line at intervals in the longitudinal direction of the closing member 215, and the main line connection port 10 is the end of the service line connection ports 200 in the line. The ports 200 are provided in the same row at intervals. The inside of the trunk line connection port 10 and the lead-in line connection port 200... Communicates with the hole of the base portion 216. As a result, the blocking member 215 passes through the front and back through the hole of the base portion 216, the inner hole of the lead-in connection port 200, and the inner hole of the main line connection port 10.

  The conductive member 220 is made of a conductive metal material and is formed in a block shape. The conductive member 220 is set so that the outer dimension corresponds to the inner dimension of the casing body 211, and is fitted into the casing body 211 with the outer surface substantially in contact with the inner surface of the casing body 211. . The conductive member 220 is set so that one surface on the opening side of the casing body 211 is recessed from the opening end of the casing body 211 by a predetermined amount in a state where the conductive member 220 is fitted into the casing body 211. . That is, in a state where the closing member 215 is attached to the casing body 211, a predetermined amount of gap (a space for accommodating the opening sealing portion 241 of the sealing member 240) is provided between the inner surface of the closing member 215 (base portion 216). Dimensioned to form.

  Further, the conductive member 220 is provided with a plurality of conductor insertion holes 223... For inserting the conductors of the low-voltage lead wires B1, B2, B3, B4 at intervals in the longitudinal direction, and the low-voltage trunk lines A1, A2. , A3, A4 conductors or trunk conductor-side conductor insertion holes 226 for inserting the branch conductors 50 are formed alongside the conductor insertion holes 223. That is, in the conductive member 220, a plurality of conductor insertion holes 223 are formed so as to be substantially concentric with the lead-in wire connection ports 200 with the opening of the casing body 211 closed with the closing member 215, A trunk line side conductor insertion hole 226 is formed so as to be substantially concentric with the trunk line connection port 10.

  As in the first embodiment, the sealing member 240 is formed by molding a gel material that can be punctured and elastically deformed by the low-voltage lead wires B1, B2, B3, and B4, and corresponds to the shape of the opening of the casing body 211. And an opening sealing portion 241 formed in a substantially rectangular plate shape, and a plurality of lead wire connection port sealing portions 242 extending from one surface of the opening sealing portion 241 and press-fitted into the lead wire connection port 200. The main line connection port sealing part 243 extends from one surface of the opening sealing part 241 and is press-fitted into the main line connection port 10.

  As in the first embodiment, the opening sealing portion 241 is interposed between the conductive member 220 fitted in the casing body 211 and the closing member 215 (base portion 216). The thickness is in close contact with the conductive member 220 and the base portion 216 of the closing member 215 with the opening of the main body 211 closed.

  The lead wire connection port sealing part 242... And the main line connection port sealing part 243 are all integrally formed with the opening sealing part 241, and the plurality of lead wire connection port sealing parts 242. .. Corresponding to the arrangement of the main line connection ports 10 of the closing member 215. Each of the plurality of lead-in connection port sealing portions 242 has a cylindrical shape whose outer diameter is set so as to correspond to the inner diameter of the lead-in connection port 200, and the outer periphery is pressed into the corresponding lead-in connection port 200. However, the lead-in connection port 200 is sealed in close contact with the inner periphery of the lead-in connection port 200. Further, the main line connection port sealing portion 243 has a cylindrical shape whose outer diameter is set so as to correspond to the inner diameter of the main line connection port 10, and the outer periphery thereof is press-fitted into the main line connection port 10. The main line connection port 10 is sealed close to the inner periphery of the main body 10.

  The branching apparatus 1 according to the present embodiment has the above-described configuration, and is a conductor exposed by removing the coating on the tip of the low-voltage trunk lines A1, A2, A3, A4, or the low-voltage trunk lines A1, A2, A3, A4. By connecting the branch conductor 50 branched from the main line connection port 10, the low-voltage main lines A1, A2, A3, and A4 are electrically connected directly or indirectly.

  The branched conductor 50 is configured such that one end side can be directly electrically connected to the low-voltage trunk lines A1, A2, A3, and A4 and the other end side can be inserted into the trunk connection port 10, and a metal material is bent. A thing, a flexible electric cable, etc. are employable. In this embodiment, as shown in FIG. 13, a branched conductor 50 formed by bending a round bar made of a metal material such as a copper material is employed. The branch conductor 50 has a connection portion 500 for extending along one side of the conductors of the low-voltage trunk lines A1, A2, A3, and A4, an extension portion 501 bent and extended from the connection portion 500, and an extension An insertion portion 502 that extends from the tip of the portion 501 and is folded and inserted into the main line connection port 10 is formed, and the connection portion 500 and the conductors of the low-voltage main lines A1, A2, A3, and A4 are connected by the compression sleeve 60. It is designed to be electrically connected. The branch conductor 50 is inserted by connecting the connecting portion 500 to the low-voltage trunk lines A1, A2, A3, A4 so that the extending portion 501 is suspended from the low-voltage trunk lines A1, A2, A3, A4. The portion 502 has an aspect of extending upward and is formed so as to be inserted into the downward main line connection port 10.

  Next, the underground low-voltage line wiring method according to the present embodiment will be described. Note that the branching device 1 employed in the present embodiment has a branch conductor 50 branched from the leading end (terminal portion) of the low-voltage trunk lines A1, A2, A3, A4 or from the low-voltage trunk lines A1, A2, A3, A4. In the following description, a wiring method using the branch conductor 50 will be described.

  First, of the pair of opposing wall surfaces Wa and Wb that define the underground space T, the opposite side to the Wa wall surface on which the drawing path R for drawing the low-voltage lead wires B1, B2, B3, and B4 is formed in the building S. The frame 40 is arranged on the wall surface Wb side. And the insulation coating of the low voltage | pressure trunk line A1, A2, A3, A4 arrange | positioned in the underground space T is partially removed, and an internal conductor is exposed. Thereafter, the connecting portion 500 of the branched conductor 50 is connected to the exposed conductor using the compression sleeve 60. At this time, as described above, the branch conductor 50 is attached so that the insertion portion 502 is in an upward state. And the insertion part 502 of the branch conductor 50 is inserted in the trunk line connection port 10, arranging the branch apparatus 1 so that the trunk line connection port 10 and the lead-in line connection ports 200.

  Then, the insertion portion 502 of the branch conductor 50 is inserted into the main line connection port sealing portion 243 and the opening sealing portion 241, and finally the main line side conductor insertion hole formed substantially concentrically with the main line connection port 10. The insertion portion 502 reaches inside the H.226. In this state, the inside is kept in a liquid-tight state by the sealing member 240 (gel) between the branch conductor 50 and the inner peripheral surface of the main line connection port 10.

  Then, the main line fixing means 250 fixes the branch conductor 50 to the conductive member 220 together with the branch conductor 50 and fixes the branch apparatus 1 to the frame (main line connection step, branch apparatus arrangement). Process). Then, the branch device 1 is attached to the low-voltage trunk lines A1, A2, A3, A4 (the ground wire A1, the power line A2, the common line A3, and the power line A4) that need to be branched in the above-described procedure (branch device). Placement process). Also in this embodiment, since the same frame 40 as in the first embodiment is employed, each branch device 1 corresponds to a plurality of beam members 401 (attachment position of the branch device 1) provided on the frame 40. Thus, when viewed from above, they are shifted from each other in the direction orthogonal to the axis of the low-voltage trunk lines A1, A2, A3, A4, and are also displaced from each other in the longitudinal direction of the low-voltage trunk lines A1, A2, A3, A4. Become.

  Of course, the branch conductor 50 can be connected to the branch device 1 (main trunk connection step) before the branch conductor 50 is connected to the low voltage main lines A1, A2, A3, A4. The arrangement of the main line connection port 10 to the low-voltage main lines A1, A2, A3, A4 (the main line connection process) may be performed first. Furthermore, any of the insulation coating removal of the low-voltage trunk lines A1, A2, A3, and A4 and the arrangement of the frame 40 may be performed first. However, when the frame 40 is made of metal and the low-voltage main lines A1, A2, A3, and A4 are energized as in the present embodiment, the conductor is in contact with the frame 40 when the frame 40 is transported. Considering the existence of danger, it is preferable to remove the insulation coating on the low-voltage trunk lines A1, A2, A3, A4 after the frame 40 is arranged or fixed as described above.

  In order to branch the low-voltage lead lines B1, B2, B3, B4 from the low-voltage main lines A1, A2, A3, A4, the insulating coating at the ends of the low-voltage lead lines B1, B2, B3, B4 is removed to expose the conductor. After that, the conductor is inserted at one of the lead-in connection ports 200. Then, the low-voltage lead wires B1, B2, B3, and B4 are pierced with respect to the lead wire connection port sealing portions 242... And the opening sealing portion 241, and finally the conductor insertion formed substantially concentric with the lead wire connection ports 200. The conductor reaches the holes 223. In this state, the inside is kept in a liquid-tight state by a sealing member 240 (gel) between the insulating coating or conductor of the low-voltage lead wires B1, B2, B3, B4 and the inner peripheral surface of the lead wire connection port 200. become.

  Thereafter, the lead-in wire fixing means 230 fixes the low-voltage lead wires B1, B2, B3, and B4 to the branch device 1 in conjunction with the electrical connection between the low-voltage lead wires B1, B2, B3, and B4 and the main line connecting portion 10 (lead wire). Connection process). Then, by closing the lid 212b of the operation unit 212, the inside is completely liquid-tight, and even if rainwater or the like flows into the underground space T and is submerged, reliable waterproofing can be achieved. become.

  Then, the low-voltage lead wires B1, B2, B3, B4 branched from the low-voltage trunk lines A1, A2, A3, A4 are inserted into the lead-in path R formed on one wall portion Wa side, and the low-voltage lead wires B1, B2 , B3 and B4 are positioned in the underground space T and the other end is positioned in the building S (retraction process). This lead-in process may be performed after the low-voltage lead lines B1, B2, B3, and B4 are branched from the low-voltage trunk lines A1, A2, A3, and A4. However, it is more likely that the lead-in connection process is performed after performing the lead-in process in advance. Since there is no low-voltage lead-in line B1, B2, B3, B4 or the like that has been pulled into the underground space T in the connection process, the work space can be effectively secured.

  Also in the present embodiment, the low-voltage service lines B1, B2, B3, and B4 are inserted and connected to the service line connection ports 200 that are directed downward as described above. B2, B3, and B4 are guided from the branching device 1 (the lead-in connection port 200) to the lead-in route R on the one wall surface Wa side while being largely curved. Therefore, the low-voltage lead-in wires B1, B2, B3, B4 are merely curved at one location, and are not bent unnecessarily in the axial direction of the low-voltage trunk lines A1, A2, A3, A4. It is possible to secure an effective work space inside. In addition, since the low-voltage service lines B1, B2, B3, and B4 can be arranged in this manner, the operation of detouring the low-voltage service lines B1, B2, B3, and B4 is not necessary. It is possible to reduce the work burden on the worker who installs B3 and B4.

  As described above, the underground low-voltage line wiring method according to the present embodiment is also required to bend the low-voltage lead wires B1, B2, B3, and B4 that are heavy and difficult to bend to the minimum necessary (for example, an arc shape having a large curvature radius). It can be disposed in the underground space T just by bending), and the work burden on the operator can be reduced.

  In addition, as described above, the low-voltage service lines B1, B2, B3, and B4 are suspended from the low-voltage trunk lines A1, A2, A3, and A4, so that the low-voltage service lines B1, B2, B3, and B4 need to be circumvented as in the past. Therefore, the occupation ratio of the low-voltage lead-in wires B1, B2, B3, and B4 with respect to the underground space T can be reduced. Thereby, it is also possible to secure a work space for adding the low-voltage lead-in wires B1, B2, B3, B4 to the limited underground space T and removing the low-voltage lead-in wires B1, B2, B3, B4.

  Further, by adopting the branching device 1 having a plurality of service line connection ports 200 as described above, the low voltage service lines B1, B2, B3, B4 are branched from a plurality of locations of the low voltage trunk lines A1, A2, A3, A4. There is no need, and the necessary number of low-voltage service lines B1, B2, B3, B4 can be branched in the underground space T of a limited size.

  Further, the branch device 1 has a trunk line connection port that can be electrically connected by inserting a branch conductor 50 branched from the terminal of the low voltage trunk lines A1, A2, A3, A4 or from the low voltage trunk lines A1, A2, A3, A4. The main line connecting step is provided as the main line connecting portion 10, and the branching conductor 50 is inserted into the main line connecting portion 10 and electrically connected to the terminal portions or the branch conductors 50 of the low voltage main lines A 1, A 2, A 3, and so on. In the device arrangement step, the branch device 1 can be arranged in a desired manner by using the branch conductor 50 having a form (length or shape) corresponding to the arrangement of the branch device 1.

  In addition, since the branch device 1 is fixed to the frame erected along the other wall surface Wb in the branch device arrangement step, the arrangement of the branch device 1 can be maintained in an appropriate state. Moreover, the connection state of the low-voltage trunk lines A1, A2, A3, and A4 and the low-voltage lead lines B1, B2, B3, and B4 can be maintained in an appropriate state.

  And in a branching device arrangement | positioning process, low pressure seeing two or more branching devices 1 ... corresponding to each of two or more low voltage | pressure main lines A1, A2, A3, A4 arrange | positioned in parallel in the underground space T from upper direction. The main lines A1, A2, A3, A4 are shifted from each other in a direction perpendicular to the axis of the main lines A1, A2, A3, A4, and are displaced in the axial direction of the low-voltage main lines A1, A2, A3, A4. , A3, and A4, the main line connection portion 10 of the branching device 1 is electrically connected, so that the low-voltage service lines B1, B2, B3, and B4 that are connected to the service line connection port 200 and are suspended are connected to other services. Each of the low-voltage service lines B1, B2, B3, and B4 is connected to the branch device 1 connected to the low-voltage trunk lines B1, B2, B3, and B4 without interfering with the low-voltage service lines B1, B2, B3, and B4 connected thereto. It can be guided to the wall Wa side.

  In addition, this invention is not limited to the said embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

  In each of the embodiments described above, the frame 40 is arranged in advance and the branch device 1 is fixed to the frame 40. However, the present invention is not limited to this. For example, the branch device 1 is attached to the wall surfaces Wa and Wb. Alternatively, the low-voltage trunk lines A1, A2, A3, and A4 may be fixed to the wall surfaces Wa and Wb, and the trunk connection portion 10 may be fixed to the low-voltage trunk lines A1, A2, A3, and A4. By connecting, the branch device 1 may be supported and fixed to the low-voltage trunk lines A1, A2, A3, and A4. In any case, however, it is a matter of course that the branching device 1 is arranged on the wall surface opposite to the side where the lead-in path R is formed so that the lead-in connection ports 200.

  In FIG. 1 for explaining each of the above embodiments, the underground space T is shown as a tunnel, but is not limited to this. For example, as described in the related art, it is intermittently arranged. A plurality of insertion pipes are connected by a branch fence, and the low-voltage lead lines B1, B2, B3, B4 are branched from the low-pressure trunk lines A1, A2, A3, A4 in the branch fence, and the other wall surface Wb in the branch fence The branch device 1 may be arranged on the side, and the low-voltage lead-in wires B1, B2, B3, B4 may be drawn into the building S from the pull-in route R on the one wall surface Wa side.

  In the above embodiment, an example in which the drawing path R is formed on one wall surface Wa side is taken as an example. However, when the drawing path R is formed on both the pair of wall surfaces Wa and Wb, the branching device 1 is used. May be arranged on the wall surface side facing the wall surface on which the target drawing-in route R is formed.

  In each of the above embodiments, the branch device 1 is used in which the lead-in connection ports 200 are sealed by the gel-like sealing member 240 that can be stabbed and elastically received by the low-voltage lead-in wires B1, B2, B3, and B4. For example, the lead-in connection ports 200 may be always open, or may be provided with a cap that closes the lead-in connection ports 200. The same applies to the main line connection port 10 in the second embodiment. However, when the lead-in connection port 200 is always open, there is a high possibility that moisture will enter the inside and corrode the conductive member 220. Therefore, the lead-in wire is connected regardless of whether the low-voltage lead-in wires B1, B2, B3, and B4 are connected. It is preferable to close the connection ports 200. In order to close the lead-in wire connection port 200 in this way, it is possible to use a waterproof tape. However, considering the convenience of the operation, the gel-like sealing member 240 is provided as in the above embodiment, It is preferable that a cap for closing the lead-in wire connection port 200 is detachably provided.

  In each of the above embodiments, on the premise that the low-voltage trunk lines A1, A2, A3, A4 are arranged in a set of four types, the branch device 1 connected to each of the low-voltage trunk lines A1, A2, A3, A4 is Although the position is shifted in the longitudinal direction of the trunk lines A1, A2, A3, A4 and the position is shifted in the direction orthogonal to the longitudinal direction of the low-voltage trunk lines A1, A2, A3, A4, the present invention is not limited to this. For example, the branching devices 1 of the low-voltage main lines A1, A2, A3, and A4 may be arranged in the same row while being shifted in the direction orthogonal to the longitudinal direction. Moreover, you may arrange | position each branch apparatus 1 shifting in the longitudinal direction of low voltage | pressure trunk line A1, A2, A3, A4. However, when a plurality of branch devices 1 are arranged side by side in the vertical direction, the low-voltage service lines B1, B2, B3, B4 hanging from the upper branch device 1 become lower-voltage low-voltage trunk lines A1, A2, A3, A4 or In this case, the low-voltage trunk lines A1, A2, A3, A4 and the branch device 1 may be suspended and suspended downward.

  In the first embodiment, the pair of sandwiching bodies 10a, 10b that sandwich the conductors of the low-voltage trunk lines A1, A2, A3, A4 are used as the trunk connection section 10, and in the second embodiment, the low-voltage trunk lines A1, A2, A3, A4. The main line connection port 10 is a main line connection port that can be electrically connected by inserting a branch conductor 50 branched from the front end portion or the low-voltage main line A1, A2, A3, A4. 1 is not limited to these. For example, the branch device 1 is divided into the branch device 1 as shown in FIGS. 14 to 16 or the branch device 1 as shown in FIGS. A first port 11a that can be electrically connected by inserting a primary side of the low-voltage trunk line A1, A2, A3, A4, and is electrically connected to the first port 11a, and the low-voltage trunk line A1, A2, A3 A4 secondary The a second port 11b can be electrically connected by inserting may be provided as a mains connection 10.

  In this case, as shown in FIGS. 17 to 19, the first port 11 a and the second port 11 b may be arranged side by side with respect to the lead-in wire connection port 200. The first port 11a and the second port 11b are provided at both ends of the apparatus body 20 (casing body 211) so that the centers of the first port 11a and the second port 11b are substantially orthogonal to the center of the lead-in connection port 200. It is preferable. Also in this case, the first port 11a and the second port 11b are formed in a cylindrical shape similarly to the lead-in wire connection port 200... And the first port 11a and the second port with respect to the conductive member 220 housed in the casing 210. 11b is formed with trunk-side conductor insertion holes 226a and 226b through which the conductors of the low-voltage trunk lines A1, A2, A3 and A4 can be inserted, and inserted into the trunk-side conductor insertion holes 226a and 226b with respect to the apparatus main body 20. What is necessary is just to provide the trunk line fixing means 250 which presses and fixes the conductor which was struck. The trunk line fixing means 250 may be formed of a screw member that goes out and withdraws from the trunk side conductor insertion holes 226a and 226b in the same manner as that corresponding to the service line connection ports 200, or similar to the service line fixing means 230. Any structure that can attach the fixing member 232 to the tip of the screw member and press the conductor may be used. It is natural that the apparatus main body 20 is provided with a main line operation unit 270 corresponding to the main line fixing means 250.

  Thus, if the main line connection part 10 is comprised by the 1st port 11a and the 2nd port 11b, the low pressure main line A1, A2, A3, A4 divided | segmented into the primary side and the secondary side in the main line connection process will be 1st port 11a. And the second port 11b may be inserted, and the work efficiency is improved without requiring the work of bending the low-voltage trunk lines A1, A2, A3, A4 in accordance with the arrangement of the branch device 1. And even if it does in this way, the 1st port 11a or the 2nd port 11b is obstruct | occluded with the gel-like sealing member G, or the cap which obstruct | occludes these with respect to the 1st port 11a and the 2nd port 11b can be attached or detached. If provided, the tip of the low-voltage trunk line A1, A2, A3, A4 can be electrically connected to only one of the first port 11a or the second port 11b, and moisture may enter from the other. Can be prevented.

  And when making the main line connection part 10 and the apparatus main body 20 into another structure like 1st embodiment, the main line connection part 10 is not limited to what was comprised by a pair of clamping body 10a, 10b, For example, as shown in FIG. 20, the main line connecting portion 10 includes a sleeve portion 150 having a C-shaped cross section, and a connected portion 151 connected to the sleeve portion 150 and connected to the conductive member 220. There may be. If it does in this way, it can electrically connect to the conductor of the low voltage | pressure main line A1, A2, A3, A4 by carrying out the crimping process of the sleeve part 150 similarly to the conventional compression sleeve. However, for example, the sleeve portion 150 and the apparatus main body 20 (the conductive member 220) are arranged so that the lead-in connection ports 200 can be directed downward in a state where the sleeve portion 150 is connected to the conductors of the low-voltage trunk lines A1, A2, A3, A4. It goes without saying that the connected portion 150 that connects the two) is bent.

  Further, as shown in FIG. 21, the main line connecting portion 10 may be formed as a clamp that sandwiches the conductors of the low-voltage main lines A1, A2, A3, and A4. Specifically, the main line connecting portion 10 includes a clamp body 160 including a pair of opposing portions 160b and 160c that are opposed to each other with a predetermined interval by connecting base ends thereof via a connecting portion 160a. The movable body 161 disposed between the opposing portions 160b and 160c and provided so as to be able to contact with and separate from one opposing portion 160b is threaded through the other opposing portion 160c and moved. One end of the body 161 is rotatably connected around the axis, and the other end is connected to a connecting screw body 162 to which the conductive member 220 is connected. At least the moving body 161 and the connecting screw body 162 are conductive. It may be formed of a certain metal material. In this way, the conductor can be sandwiched between one opposing portion 160b and the moving body 161 to electrically connect the main line connecting portion 10 and the conductor, and the connecting screw body 162 can be rotated in the other direction. By doing so, the pinching (connection) to the conductor can be released and the conductor can be easily detached from the low-voltage trunk lines A1, A2, A3, A4. Also in this case, the main line connection portion 10 (the connecting screw body 162) is provided so that the lead-in connection ports 200 can be directed downward in a state where the main line connection portion 10 is connected to the conductors of the low-voltage main lines A1, A2, A3, and A4. Of course, the apparatus main body 20 (conductive member 220) is connected.

  In each of the above embodiments, the fixing member 232 is attached to the distal end portion of the push screw 231 as the lead-in wire fixing means 230. However, the present invention is not limited to this. For example, the lead-in wire fixing means 230 is configured only by the push screw 231. Also good. In the above embodiment, the push screw 231 is screwed into the conductive member 220. However, for example, a through hole may be formed in the conductive member 220 and the push screw 231 may be screwed into the casing 210. Then, the push screw 231 may be screwed into the conductive member 220 and the casing 210.

  Further, in each of the above embodiments, the low voltage lead wires B1, B2, B3, B4 are fixed by the lead wire fixing means 230, but the present invention is not limited to this. For example, the conductor insertion holes 223. The lead-in wire fixing means 230 is constituted by protrusions and claws or the like that are projected on the inner peripheral surface of the wire, and the low-voltage lead wires B1, B2, B3, and B4 inserted into the conductor insertion holes 223 are locked to the protrusions and claws. You may make it prevent dropout. Further, the conductor insertion holes 223... May be formed to have substantially the same diameter as the conductors of the low-voltage lead wires B1, B2, B3, B4, and the conductors may be press-fitted into the conductor insertion holes 223. Therefore, when it is not necessary to operate the lead-in wire fixing means 230 from the outside, it is not necessary to provide the operation unit 212.

  In the second embodiment, the branch conductor 50 that connects the low-voltage trunk lines A1, A2, A3, and A4 and the trunk line connection portion (trunk line connection port) 10 is formed by bending a bar, and the connection portion. 500 is electrically connected to the low-voltage trunk lines A1, A2, A3, and A4 by the compression sleeve 60. For example, the connection portion 500 of the branch conductor 50 is paired similarly to the trunk connection portion 10 of the first embodiment. The conductors of the low-voltage trunk lines A1, A2, A3, and A4 may be sandwiched between the pair of sandwiching bodies.

It is explanatory drawing of the low voltage | pressure line used as the premise of the underground low voltage line wiring method which concerns on embodiment of this invention, Comprising: The schematic sectional drawing of the underground space by which the low voltage | pressure main line and the low voltage | strand lead-in line were arrange | positioned is shown. The whole perspective view except a part (waterproof cover) of a branching device adopted for the underground low-voltage line wiring method concerning a first embodiment of the present invention is shown. The longitudinal cross-sectional view except a part (waterproof cover) of the branch apparatus employ | adopted for the underground low voltage | pressure wiring method which concerns on 1st embodiment is shown. The cross-sectional view except a part (waterproof cover) of the branching device employed in the underground low-voltage line wiring method according to the first embodiment is shown. It is a perspective view of the waterproof cover of the branch apparatus employ | adopted for the underground low voltage | pressure wiring method which concerns on 1st embodiment, Comprising: The state which opened the division | segmentation cover is shown. It is explanatory drawing of the flame | frame employ | adopted for the underground low voltage | pressure wiring method which concerns on each embodiment of this invention, Comprising: (a) shows a schematic front view, (b) shows a schematic side view. It is explanatory drawing of the trunk line connection process of the underground low voltage line wiring method which concerns on 1st embodiment, Comprising: (a) shows the state which connected the trunk line connection part of the branching apparatus to the conductor of the low voltage | pressure trunk line, (b) is The state which covers a main line connection part with a waterproof cover is shown. It is explanatory drawing of the service line connection process of the underground low voltage line wiring method which concerns on 1st embodiment, Comprising: The state which connects a low voltage service line to a branch apparatus is shown. The longitudinal cross-sectional view of the underground space of the state which branched the low voltage | pressure lead-in line from the low voltage | pressure main line with the underground low voltage line wiring method which concerns on 1st embodiment is shown. The whole perspective view of the branch apparatus employ | adopted for the underground low voltage line wiring method which concerns on 2nd embodiment of this invention is shown. It is a longitudinal cross-sectional view of the branch apparatus employ | adopted for the underground low voltage line wiring method which concerns on 2nd embodiment, Comprising: (a) shows sectional drawing facing arrangement | positioning of the lead-in wire connection port, (b) is trunk line Sectional drawing corresponding to arrangement | positioning of a connection port is shown. The cross-sectional view of the branch apparatus employ | adopted for the underground low voltage line wiring method which concerns on 2nd embodiment is shown. The perspective view of the state which branched the low voltage | pressure lead-in line from the low voltage | pressure trunk line with the underground low voltage line wiring method which concerns on 2nd embodiment is shown. The whole perspective view of the branch apparatus employ | adopted for the underground low voltage | pressure wiring method which concerns on other embodiment of this invention is shown. Fig. 15 shows a cross-sectional view of the branching device of Fig. 14. The perspective view of the state which branched the low voltage | pressure lead-in line from the low voltage | pressure trunk line with the underground low voltage line wiring method using the branch apparatus of FIG. The whole perspective view of the branch apparatus employ | adopted for the underground low voltage | pressure wiring method which concerns on another embodiment of this invention is shown. FIG. 18 shows a cross-sectional view of the branching device of FIG. The perspective view of the state which branched the low voltage | pressure lead-in line from the low voltage | pressure trunk line by the underground low voltage line wiring method using the branch apparatus of FIG. The whole perspective view of the branch apparatus employ | adopted for the underground low voltage line wiring method which concerns on another embodiment of this invention is shown. The whole perspective view of the branch apparatus employ | adopted for the underground low voltage line wiring method which concerns on another embodiment of this invention is shown. The perspective view of the state which branched the low voltage | pressure lead-in line from the low voltage | pressure trunk line with the conventional wiring method is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Branch apparatus, 10 ... Main line connection part (main line connection port), 10a, 10b ... Holding body, 11a ... First port, 11b ... Second port, 20 ... Apparatus main body, 30 ... Waterproof cover, 40 ... Frame, 50 ... Branch conductor, 60 ... Compression sleeve, 100a, 100b ... Holding body, 101a, 101b ... Flange part, 150 ... Sleeve part, 151 ... Connected part, 160 ... Clamp body, 160a ... Connecting part, 160b ... opposite part , 160b, 160c ... opposing portion, 161 ... moving body, 162 ... coupling screw body, 200 ... lead-in wire connection port, 210 ... casing, 211 ... casing main body, 211a ... main body housing portion, 211b ... cylindrical housing portion, 211c ... convex Piece 212, operation portion, operation portion for lead-in wire, 212a ... cylindrical portion, 212b ... lid portion, 212c ... packing, 212d ... locking claw, 212 ··· locked portion, 215 ··· closure member, 216 ··· base portion, 220 ··· conductive member, 221 ··· conductive member body, 222 ··· connected conductive portion, 222a ··· connected body portion, 222b ··· connecting portion, 223 ··· conductor insertion hole, 224 ... Screw hole, 225 ... Recess, 226 ... Main line side conductor insertion hole, 226a, 226b ... Main line side conductor insertion hole, 230 ... Lead wire fixing means, 231 ... Push screw, 231a ... Male screw part, 231b ... Pin part, 232 ... fixing member, 232a, 232a ... pressing piece, 232b ... connecting piece, 240 ... sealing member, 241 ... opening sealing part, 242 ... drawing line connection port sealing part, 243 ... main line connection port sealing part, 250 ... main line fixing Means, 270 ... main line operation section, 300 ... cover main body, 300a, 300b ... split cover, 301, 302, 303 ... hole, recess ... 301a, 301b, 30 a, 302b, 303a, 303b, 310 ... sealing member, 400 ... leg material, 401 ... beam material, 402 ... arm, 403 ... bolt hole, 500 ... connection part, 501 ... extension part, 502 ... insertion part, A1 ... Earth line (low-voltage trunk line), A2 ... Electric light line (low-voltage trunk line), A3 ... Shared line (low-voltage trunk line), A4 ... Power line (low-voltage trunk line), B1 ... Earth line (low-voltage lead line), B2 ... Electric light line (low-voltage lead line) ), B3 ... shared line (low-voltage lead-in line), B4 ... power line (low-pressure lead-in line), R ... lead-in route, S ... building, T ... underground space, Wa, Wb ... wall surface

Claims (5)

A low-voltage lead-in line is formed in a lead-in path formed on at least one of a pair of wall surfaces that diverge a low-voltage lead-in line from a low-pressure trunk line arranged in the underground space and define the underground space facing each other. An underground underground low-voltage line wiring method for drawing a cable into a building and inserting a plurality of low-voltage lead lines from the same direction, each of which can be directly or indirectly electrically connected to the low-voltage main line. A branch device that is configured to be insertable and has a plurality of service line connection ports to which the inserted low-voltage service lines are electrically connected to the main line connection section is arranged on the other wall surface side so that the service line connection port faces downward A branching device placement step for electrically connecting the main line connection portion to the low-voltage main line, and a lead-line connection step for inserting the low-voltage lead wire into the lead-in connection port and electrically connecting to the main line connection portion, , Underground low voltage line wiring method characterized by comprising a pull step of inserting a low pressure drop cable to write path.
  The trunk line connecting portion of the branching device is electrically connected to each service line connection port, and includes a pair of sandwiching bodies configured to be electrically connected to the low-voltage trunk line by sandwiching the low-voltage trunk line. 2. The underground low-voltage line wiring method according to claim 1, wherein the low-voltage trunk line is sandwiched between a pair of sandwiching bodies to be electrically connected.   The main line connecting portion of the branching device is configured to be electrically connectable by inserting a branch conductor branched from the end of the low-voltage main line or the low-voltage main line, and the main line connecting step includes the terminal portion of the low-voltage main line or the branch conductor. The underground low-voltage line wiring method according to claim 1, wherein the underground low-voltage line wiring method is inserted into the main line connection portion and electrically connected.   The underground low-voltage line wiring method according to any one of claims 1 to 3, wherein the branching device arranging step fixes the branching device to a frame erected along the other wall surface.   The branching device arrangement step is shifted from each other in a direction perpendicular to the axis of the low-pressure trunk line when two or more branching devices corresponding to each of two or more low-pressure trunk lines arranged in parallel between the hollow spaces are viewed from above. 5. The underground low-voltage line according to claim 1, wherein the main line connection step is configured to electrically connect a main line connection portion of a corresponding branch device to each low-voltage main line. Wiring method.

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