JP4367792B1 - Cable drawing method and protective device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To take measures against an abnormal tensile action of a cable by a simple operation without using an expensive tool.
A branch cable (10) having a main line (11) for signal transmission and a supporting line (12) attached to the main line (11) is branched from a trunk cable system and drawn into the building. A main fixing portion (30) for initially fixing the branch cable (10) to the outer wall (20) from the trunk cable system is formed, and is delivered between the main fixing portion (30) and the cable inlet (21) of the building. A part of the support wire (12) is removed from the portion of the cable (10), and the cable portion (10p) in which only the main wire (11) remains by the removal is wound in a ring shape to form a winding portion (11r), A protective device (50) for holding the winding is attached to the winding part (11r) by inserting the wound cable portion. When the cable (10) is pulled from the building in the direction of the trunk cable system, the protective device (50) preferentially cuts the cable portion that hits the edge of the protective device (50) at the edge over the other cable portions. Configured as possible.
[Selection] Figure 2

Description

  The present invention generally relates to a cable drawing method, and in particular, a method for drawing a communication cable such as an optical fiber cable or a signal transmission cable from an optical fiber trunk cable system constituting an optical wiring network into a building such as a house and the like. The present invention relates to a facility, and a member for protecting an indoor system used in these cases when the cable is abnormally pulled.

  Patent Document 1 discloses this type of cable drawing method. According to this, an optical rosette that uses a splice such as an adhesive method or a mechanical method installed in a home, and is connected to a closure that is connected to the optical rosette at one end and the other end is installed outdoors. An optical fiber cord branched from a fiber trunk cable, a tensile strength member made of a synthetic resin material capable of reinforcing against tension such as FRP arranged at both sides of the optical fiber cord and spaced apart by a predetermined distance, An optical fiber cable main body comprising a sheath covering the outer peripheral portion of the optical fiber cord, and one side surface of the sheath excluding a portion located in the house of the optical fiber cable main body is integrally formed on the outer peripheral portion via a connecting portion. Provided with an optical fiber cable comprising a metal support wire and a support wire sheath covering the metal support wire It is. Thereby, it becomes possible to connect between the optical rosette in a house and the closure branched from the outdoor optical fiber trunk cable with one optical fiber cable.

  In such a wiring form, there may be a case where safety measures are not taken in consideration of the action of an abnormal pulling force that pulls an optical fiber cable (hereinafter, abbreviated as an optical cable as appropriate) from the building to the main cable side. For example, when a load-carrying truck that ignores the height restriction runs on an optical cable that is installed between telephone poles, and the optical cable is pulled, the outer wall of the building that fixes the optical cable may be damaged. The indoor wiring connected to the optical cable and the connected equipment can also be pulled to cause disconnection or failure.

  In order to prevent such a situation, it is desired that when an abnormal pulling action of the cable occurs, this is kept only outdoors so as not to affect the wiring and connection status of the optical cable indoors. Specifically, a cable location that can be cut preferentially or easily over other locations by such an abnormal tensile action is provided in the previous stage of drawing the optical cable indoors. For example, at any point between the branch point of the optical fiber trunk cable and the drawing-in position of the building, the support line is partially removed to form only the optical fiber cable main body, or only the support line Alternatively, it is also possible to envisage a method in which a part of the optical fiber cable main body including only the optical fiber cord is formed by removing a part of the sheath including the strength member.

However, these measures are basically based on the idea of reducing the strength against pulling of the cable at a desired location. In order to achieve this, the work of separating the support line and the optical fiber cable body, and further the optical The operation | work which isolate | separates a fiber cable main body into an optical fiber cord and an other than that part is accompanied. Such an operation is time-consuming, and in particular, an extremely expensive tool needs to be used for the operation of separating the optical fiber cord from other parts.
JP 2004-219611 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to take measures against an abnormal tensile action of a cable with a simple operation without using an expensive tool.

  In order to achieve the above object, a specific aspect of the present invention is a method of branching a branch line cable having a main line for signal transmission and a support line attached to the main line from a trunk cable system and drawing it into a building. A step of forming a main fixing portion for first fixing the branch line cable on the outer wall of the building or other building outer shape portion from the main cable system, and being delivered between the main fixing portion and the cable inlet of the building Removing a part of the support line from the branch cable part, forming a winding part by winding the cable part where only the main line remains by the removal into a ring shape, the winding part, Attaching a protector that passes through the wound cable portion and holds the winding, and the protector has the branch cable from the building to the building. When it is pulled to the line cable system direction it is configured cable portion striking the edge of the protective equipment than other cable portion so as to be cut by preferentially that edge.

  In order to achieve the above object, another specific aspect of the present invention is that a branch cable having a main line for signal transmission and a support line attached to the main line is branched from the main line cable system to the inside of the building. A protective device used for a drawing-in method, having a through hole for loose insertion of at least two main lines, and the branch cable is first formed from the trunk cable system on the outer wall of the building or other building outer shape. A main fixing portion fixed to the cable is formed, and a part of the support line is removed from a portion of the branch cable that is handed over between the main fixing portion and the cable inlet of the building, and only the main line is removed by the removal. In the situation where the cable portion where the wire remains is wound in a ring shape and the winding portion is formed, the winding is performed so as to hold the winding by inserting the wound cable portion into the through hole. When the branch cable is pulled from the building in the direction of the trunk cable system, the cable portion that hits the edge of the protective device is preferentially cut at the edge than the other cable portions. It is configured to be possible.

  According to these aspects, it is possible to take measures against an abnormal tensile action of the cable with a simple operation without using an expensive tool.

  An embodiment according to the present invention is a method of branching a branch cable having a main line for signal transmission and a support line attached to the main line from a trunk cable system and drawing the branch cable into a building, wherein the branch cable is connected to the main line. From the step of forming a main fixing portion to be fixed first from the trunk cable system on the outer wall of the building or other building outer shape, and from the branch cable portion handed over between the main fixing portion and the cable inlet of the building A step of removing a part of the support wire, a step of winding a cable portion where only the main wire remains by the removal to form a winding portion, and a cable wound around the winding portion. Attaching a protector that passes through the location and holds the winding, and the protector is configured so that the branch cable is in the direction of the trunk cable system from the building. When pulled, and a cable portion which corresponds to the edge of the protective equipment than other cable portion so as to be cut by preferentially that edge is a method (claim 1).

  According to this method, the cable part that hits the edge of the protective device is prioritized over the other cable parts with respect to the abnormal pulling of the branch cable in the winding part formed by winding the cable part with only the main line remaining in a ring shape. A protective device that can be cut at the edge is attached. The attachment is performed in a simple form in which the wound cable portion is inserted through the protective device. Therefore, it is not necessary to separate the conventional optical fiber cable body into an optical fiber cord and other parts (such as a tensile body), and an expensive tool is not used. In addition, no special tools are required for cable winding work and protection equipment installation, and only manual work is required. Therefore, the entire installation work can be simplified, and measures against abnormal tensile action of the cable can be realized reliably. it can.

  In this embodiment, between the main fixing part and the cable inlet, a sub fixing part for fixing the branch cable to the building outer shape part on the side of the cable inlet, the main fixing part and the sub fixing You may make it hand over the cable location where only the said main line remains between the parts (Claim 2). As a result, the position of the winding portion, and thus the position of the cable to be cut when an abnormal pulling of the cable occurs, is defined, and a more stable safety measure is achieved.

  The main line includes an optical fiber cord and a tensile body wire attached to both sides or one side thereof, and the support line is a core formed of a plastic material having rigidity higher than that of the main line. (Claim 3). Thereby, the favorable indoor lead-in form of an optical cable can be provided.

  Further, in the case of providing the sub-fixing portion, the main fixing portion may be configured based on an S metal fitting and / or the sub-fixing portion may be configured based on a wiring cleat. ). This is advantageous because the present invention can be realized with simple and inexpensive members that have been conventionally used.

  Another embodiment of the present invention is a protective device used in a method of branching a branch cable having a main line for signal transmission and a support line attached to the main line from the trunk cable system and drawing it into the building. A main fixing portion having a through hole for loosely inserting at least two main lines, the branch cable being first fixed from the trunk cable system to the outer wall of the building or other building outer shape portion. A part of the support wire is removed from the portion of the branch cable that is handed over between the main fixing portion and the cable entrance of the building, and the cable portion where only the main wire remains is wound in a ring shape by the removal. In the situation where the winding part is formed, the cable part wound through the through hole is inserted and the winding part is configured to be attached to the winding part so as to hold the winding. When the branch cable is pulled from the building in the direction of the trunk cable system, it is possible to preferentially cut the cable portion that hits the edge of the protective device at the edge over the other cable portions. It is the protective device comprised (Claim 5).

  According to this protective device, by attaching the winding portion formed by winding the cable portion with only the main wire remaining in a ring shape into the through hole, the protective device can be attached to the winding portion and the winding Can be held. Therefore, a very simple mounting operation is sufficient. Moreover, this protective device can cut | disconnect the cable location which hits the edge of the said protective device with the edge preferentially over the other cable location with respect to the abnormal pulling effect | action of a branch line cable. This is because when such a cable pulling action occurs, a cable without a support wire is wound around the protective device with a very small curvature, and the cable is marked at the contact position between the cable and the edge of the protective device. It is based on the fact that the shearing force is applied in a concentrated manner, and further development of the tension eventually leads to cable cutting at that position. In this embodiment, it is based on the idea of providing means for actively cutting the cable at a desired location in the event of an abnormality, and with respect to the abnormal tension action of the cable with a simple operation without using an expensive tool as in the past. Measures can be taken.

  In this embodiment, it has a substantially cylindrical main body, and the main body is formed with a slit that can be inserted into the cylindrical hollow portion by inserting the cable crossing portion of the wound cable portion from the side surface. (Claim 6). Thereby, the protector which is very easy to manufacture can be provided. In addition, the slit may be formed to be curved and extend on the side surface of the main body (Claim 7). Thereby, once a cable is inserted and attached to the hollow part of a protective device, there exists an advantage that a cable becomes difficult to remove | deviate from the hollow part through a slit.

  Alternatively, it has a substantially flat main body instead of a cylindrical main body structure, and the main body has a through-hole extending in the thickness direction of the main body for loosely inserting the wound cable portion. A slit that can communicate with the through-hole from the side of the flat plate-like main body and can be inserted into the through-hole by inserting the cable crossing portion of the wound cable portion from the side surface. (Claim 8). Thereby, while being able to provide the protector which is easy to manufacture, since a main body is made into flat form, there exists an aspect that it is easy to store and handle. In addition to this, if the slit has an arc-shaped cross section (Claim 9), the cable loosely inserted into the protective device is unlikely to come off from the protective device. Furthermore, if it has an additional part connected to the said flat main body at right angles or other predetermined angles, or it extends continuously, the fixing device can be fixed using this additional part (claim 10). The protective device can be easily fixed to the outer wall of the building, for example.

  Hereinafter, the above aspect and embodiment of the present invention will be described in detail based on examples with reference to the accompanying drawings.

(Example 1)
1 and 2 show a cable installation configuration configured by a cable drawing method according to an embodiment of the present invention. The branch cable 10 branched from the trunk cable system (not shown) is delivered toward the outer wall 20 of the building via a predetermined branching facility such as a utility pole 35 and a closure 36 installed therein. As will be described later, the branch cable 10 is an optical cable also called an IF drop in this example, and its structure is roughly divided into two. The main line 11 for optical communication and the main line 11 associated with the main line 11 It is composed of a support wire 12 for facilitating an overhead wire and stabilizing or reinforcing the cable installation state. In FIG. 2, for the sake of simplicity, the main line 11 is indicated by a white line and the support line 12 is indicated by a black line.

  FIG. 3 shows a more detailed configuration of the optical cable 10, in which the main line 11 and the support line 12 attached to the main line are coupled by a connecting part (neck part) 100 with their side parts facing each other. The main line 11 includes an optical fiber cord 110 disposed in the center, tensile strength body wires 111 arranged on both sides of the cord at a predetermined interval, and a sheath portion that covers the entire optical fiber cord 110 and the tensile strength body wire 111. 112. The tensile body wire 111 is also called a tension member, and is a thin line made of a synthetic resin material that can reinforce against tension such as G-FRP and K-FRP. The sheath portion 112 is formed of a thermoplastic resin, and a pair of opposed V grooves 11v formed along the optical fiber cord 110 is formed between one and the other of the tensile body wires 111 on the outer surface thereof. (Upper and lower in FIG. 3). Using the V groove 11v, the optical fiber cord 110 is stripped from the sheath portion 112.

  The optical fiber cord 110 includes an optical fiber core wire 11a, a high-tensile fiber 11b that covers the core wire, and a flame-retardant sheath 11c formed of polyethylene or the like that covers the fiber 11b.

  The support wire 12 has a support core wire 120 and a sheath portion 121 that covers the core wire, and is coupled to the main wire 11 via the connecting portion 100 so as to face one of the strength body wires 111. The sheath portion 121 is preferably formed of the same material as the sheath portion 112 of the main line 11, and more preferably formed integrally with the sheath portion 112 and the connecting portion 100. The core wire 120 of the support wire 12 is preferably formed of a plastic material having higher rigidity than the main wire 11, for example, a steel material.

  The main line 11 and the support line 12 are separated by cutting the connecting portion 100 having a relatively small strength in the longitudinal direction. The separation and separation of the main line 11 and the support line 12 as well as the separation of the optical fiber cord 110 or the optical fiber core wire 11a from the main line 11 and the other portions are the methods and forms described above in JP-A-2004-205609. Are not described in detail here. In FIG. 3, the connecting portion 100 is depicted as a substantially flat extending portion having a thickness of about one-fifth of the sheath portions 112 and 121. However, the connecting portion 100 may be appropriately sized and shaped as appropriate.

  Returning again to FIG. 2, the branch cable 10 from the trunk cable facility is firstly attached to the outer wall 20 as the outer portion of the building into which the cable is to be drawn from the trunk cable system by the main fixing portion 30 formed on the outer wall. Fixed. The main fixing portion 30 is a combination of a so-called S metal fitting 31 and a S metal fitting 31 that can adjust the length of the support wire 12 by winding the support wire 12 and the S metal fitting 31. It has what is called a C metal fitting 33 as a fixture fixed to the outer wall 20 while holding. The S metal fitting 31 is additionally provided with a hooking loop 32, and the C metal fitting 33 is provided with a hook portion 34 that hooks the loop 32 from above. The S metal fitting 31 and the C metal fitting 33 are simple and inexpensive mounting members that have been used conventionally.

  A sub-fixing portion 41 is provided on the cable inlet 21 side between the main fixing portion 30 and the cable inlet 21 formed in the wall portion 20. In this example, the sub-fixing portion 41 is configured by a so-called wiring cleat as a fixing tool that can be held and fixed to the outer wall 20 by a holding structure that holds the branch cable 10. This wiring cleat is a simple and inexpensive member conventionally used. Between the sub-fixing portion 41 and the main fixing portion 30, the cable portion 10p where only the main line 11 remains is handed over. In addition, the main line 11 branches from the support line 12, and the protection tape 12a is wound around the said part. Furthermore, the cable drawing work requires a step of removing a part of the support wire 12 from the branch cable portion delivered between the main fixing portion 30 and the cable drawing port 21.

  As shown in FIG. 2, the cable portion 10p remaining only in the main line 11 obtained by such removal forms a cable winding portion 11r in a ring shape (in this example, it is wound once). A protector 50, which is the main feature of the present invention, is attached to the winding portion 11r and holds the winding by inserting the wound cable portion 10p.

  The protective device 50 is a member for protecting the indoor system when the cable is abnormally pulled, and includes an edge having a cable cutting function. The protective device 50 is configured such that when the branch cable 10 is pulled from the building in the direction of the trunk cable system, the cable portion that hits the edge of the protective device 50 can be cut preferentially at the edge over the other cable portions. Has been.

  According to such a cable drawing-in method, the cable portion that hits the edge of the protective device 50 against the pulling action of the branch cable 10 is formed on the winding portion 11r formed by winding the cable portion 10p that leaves only the main line in a ring shape. A protective device 50 that can be cut at the edge of the cable in preference to other cable points is attached. The attachment is performed in a simple form in which the wound cable portion 11r is inserted into the protective device 50. Therefore, it is not necessary to separate the conventional optical fiber cable main body into the optical fiber cord and the other parts, and an expensive tool is not used. Moreover, no special tools are required for the cable winding operation and the installation of the protective device 50, and only a manual operation is required. Therefore, the entire installation operation is simplified, and a countermeasure for the abnormal tensile action of the cable is surely realized. Can do.

  The auxiliary fixing portion 41 is not necessarily provided, but by providing the auxiliary fixing portion 41, the position of the winding portion 11r, and thus the position of the cable 10 to be cut when the cable 10 is abnormally pulled, It has an additional effect that more stable safety measures can be taken.

  4 and 5 are so-called sleeve types of the protective device 50, and show different examples of specific forms. Although both have a cylindrical body, FIG. 4 shows a protective device 51 having a slit 5s extending in a relatively simple curve. On the other hand, FIG. 5 shows a protective device 52 having a slit 5s' extending in a relatively complicated curve.

  The protective device 51 is formed of a moldable metal material such as aluminum or stainless steel or a hard plastic, for example. In the longitudinal direction, there are through holes, that is, hollow portions 500 for loosely inserting at least two main wires 11 of the cable 10. As described above, in the winding portion 11r between the main fixing portion 30 and the cable lead-in port 21, winding is performed so that the cable portion wound in the through hole 500 is inserted and the winding is held. It is attached to the part 11r. In fact, good results have been obtained with the protective device 51 formed with a length of the protective device 51 of about 30 mm, a diameter of the hollow portion of 7 to 9 mm, and a maximum slit width of 1.8 mm. At this time, the diameter of the ring of the winding part 11r of the cable loosely inserted was set to a minimum of 100 mm. The protective device 51 causes the main cable 11 to be tightly wound around the protective device 51 when the cable 10 is abnormally pulled in the direction from the building to the trunk cable system, and further, the edge of the protective device 51 is caused by the progress of the pulling. The cable location corresponding to 5e can be preferentially cut at the edge 5e over other cable locations. In the present example, when the winding of the main line cable 11 is reduced so that its winding is less than 50 mm, the transmission efficiency is remarkably reduced. Therefore, it was found that the length of the protective device 51 is a suitable size for such a cable.

  Therefore, the protective device 51 can be attached by a very simple operation. In particular, the protective device 51 has a cylindrical main body, and has a slit 5s that can be inserted into the cylindrical hollow portion 500 by inserting the cable crossing portion 11c of the wound cable portion 11r from the side surface of the cylindrical body. Since it is formed on this main body, it can be attached very easily and is very easy to manufacture. Moreover, since the slit 5s is formed to bend and extend on the side surface of the main body, once the cable 11 is inserted and attached to the hollow portion 500 of the protective device 51, the cable 11 is slit from the hollow portion. There is an advantage that it is difficult to come off through 5s.

  Considering that the cable portion that hits the edge 5e of the protective device 51 when the protective device 51 abnormally pulls the branch cable 10 is cut preferentially at the edge over the other cable locations, When a pulling action occurs, the cable 10p without the support wire 12 is wound around the protective device with a very small curvature, and a significant shearing force is applied to the cable 10p at the contact position between the cable 10p and the edge 5e of the protective device 51. Is applied in a concentrated manner, and the progress of the tension finally relies on the cable being cut at the position. Countermeasures against the abnormal tensile action of the cable 10 can be achieved with a simple operation without using an expensive tool as in the prior art.

  The protective device 52 of the other form shown by FIG. 5 is the same as that shown by FIG. 4 except the point that the curved form of slit 5s' became complicated, and an effect. The slit 5 s ′ is curved in an S shape as shown in FIG. 5, and leads to an additional effect that the inserted cable is less likely to come off than the slit 5 s extending in an arc shape in FIG. 4.

  There are various other preventive measures for preventing the inserted cable from being removed from the protective device. For example, the slit formed in the protective device may extend linearly, and even if the outer periphery of the protective device is wrapped with tape after the cable is inserted, at least a part of the slit can be prevented from falling off. Further, as shown in the cross section of the protective devices 51 and 52 in FIG. 6, after inserting the cable, the end portions of the protective device main body forming the slit wall surface are overlapped, and the slit gap in the direction perpendicular to the main body side surface is overlapped. May be eliminated. According to this, since the center of gravity of the protective device is changed so that the overlapped portion faces down, the cable crossing portion 11c always takes the appearance of contacting the protective device portion facing the slit portion in a steady state. That is, it becomes the appearance away from the slit portion that can form the cable dropout path, and contributes to prevention of dropout. In addition, there is an advantage that it is easy to define the contact position between the protectors 51 and 52 and the cable 11.

(Example 1 ')
7 and 8 show a protective device 151 that is a modification of the protective devices 51 and 52. Pipes 153a and 153b divided in the longitudinal direction are accommodated in a protective case 152 formed of two members 152a and 152b that are engaged with each other so as to be freely opened and closed. The protective case 152 is made of plastic. In the case where the protective case 152 is made of hard plastic or the like, the shapes of the pipes 153a and 153b may be directly formed thereon.

  When the pipes 153a and 153b are combined so as to close the protective case 152, a single tubular body is formed. In the longitudinal direction, there is a space for loosely inserting at least two main wires 11 of the cable 10. With two main wires 11 loosely inserted, the protective case 152 is closed so that it can no longer be opened easily. Since the formation of the winding part 11r by the main line 11 at this time has been described above, it will be omitted.

  Furthermore, the protective device 151 has a mounting hole 154 and can be fixed to the outer wall 20 of the building by inserting a wood screw or the like, for example. By this fixing, the cable cutting position at the time of abnormality can be determined. For this, see also the description in the second embodiment.

(Example 2)
FIG. 9 shows a protective device 53 according to another embodiment of the present invention. Here, unlike the embodiment shown in FIGS. 4 and 5, the protective device 53 has a substantially flat main body 530. The main body 530 communicates with the through-hole 531 from the side hole 532 of the flat body 530 and the through-hole 531 extending in the thickness direction of the main body 530 for loosely inserting the wound cable portion. A slit 53 s that can be inserted into the through hole 531 by inserting the cable crossing portion 11 c of the cable portion from the side surface is formed.

  Such a relatively simple protective device is easy to manufacture. Further, since the main body is flat, storage and handling are facilitated.

  In this example, the slit 53s has an arcuate cross section as shown in FIG. As a result, the cable 11 loosely inserted into the protective device 53 is unlikely to be detached from the protective device 53. Instead of this, it is possible to tap so as to block at least a part of the slit 53s.

  In this example, the protective device 53 further includes an incidental portion 533 that is connected or continuously extended to the flat plate-like main body 530 at a right angle. For example, a wood screw or the like can be inserted into the attachment hole 533a of the auxiliary portion 533 so that the protective device 53 can be fixed. Actually, it becomes easy to fix the protective device 53 to the building outer wall 20, for example. In addition, this fixing has an advantage that the cable cutting position at the time of abnormality can be determined. Here, the angle formed by the flat plate-like main body 530 and the incidental portion 533 is a right angle, but may be an appropriate angle other than this as appropriate.

  In comparison between the protective devices 51 and 52 shown in FIGS. 4 and 5 and the protective device 53 shown in FIG. 9, the former does not limit the pulling direction of the cable 10, whereas the latter is a wound cable in an abnormal state. There is a feature that the cable 10 must be oriented to be pulled so that 11 is brought into contact with a predetermined edge portion of the through hole 531.

In the above-described embodiment, the mode in which the cable is routed substantially horizontally from the main fixing portion 30 to the service port 21 has been described. However, the present invention is not limited to this, and the cable routing may be made vertical. The present invention can be applied in any form such as slanting or forming a corner.
In each of the above-described embodiments,
A step of forming a main fixing portion 30 for first fixing the branch cable 10 to the building outer shape portion 20 from the trunk cable system;
Removing a part of the support wire 12 from the portion of the branch cable 10 delivered between the main fixing portion 30 and the cable inlet 21 of the building;
A step of winding the cable portion 10p in which only the main wire 11 remains by the removal into a ring shape to form a winding portion 11r;
A step of attaching the protective device 50 that holds the winding by inserting the wound cable portion 10p into the winding portion 11r;
A form having is derived. These steps may be performed in the order as described above, but the order is not necessarily limited, and may be appropriately replaced in time series or performed in parallel. The top-level concept is also intended for such replacement and parallel processing.

  Moreover, in the said Example, although the number of cable turns of the winding part 11pr is 1, you may make it 2 or more, and the details of a cable are not necessarily limited to what was demonstrated with reference to FIG. Of course.

  As mentioned above, although the typical Example by this invention and the modification based on this were demonstrated, this invention is not necessarily limited to these, Those skilled in the art do not deviate from the scope of the attached claim. Various alternative embodiments and modifications can be found.

It is a schematic perspective view which shows the cable installation form comprised by the cable drawing-in method by one Example of this invention. It is a schematic perspective view which shows the principal part of FIG. It is a schematic perspective view which shows the detailed structure aspect of an optical cable. It is a schematic perspective view which shows the protective device by one Example of this invention. It is a schematic perspective view which shows the other protective device by one Example of this invention. It is a schematic sectional drawing which shows the form after attachment of the protection instrument of FIG.4 and FIG.5. FIG. 6 is a perspective view showing a protective device according to another embodiment of the present invention. It is a perspective view which shows the one aspect | mode of the protective device of FIG. It is a perspective view which shows the protection instrument by further another Example of this invention.

Explanation of symbols

5e Edges 5s, 5s ′, 53s Slit 10 Cable 11 Main line 11r Winding portion 12 Support wire 20 Outer wall 21 Lead-in port 30 Main fixing portion 31 S metal fitting 32 Hanging loop 33 C metal fitting 34 Hook portion 41 Sub fixing portions 50, 51, 52,53 Protection device 500,531 Through hole

Claims (7)

A branch cable composed of an optical fiber main line having an optical fiber cord and a tensile body wire attached to both sides or one side thereof and a support line attached to the main line and serving as an overhead line is branched from the main cable system and drawn into the building. A protective device used in the method,
The body,
The optical fiber main line is provided in the main body so that a crossed base portion of a winding portion in which a part of the support line is removed and only the optical fiber main line is left to form a ring shape can be accommodated therein. Through hole that can be loosely inserted,
A slit that is provided substantially in parallel with the direction in which the through hole extends and can guide the optical fiber main line from the outside of the main body to the through hole to be loosely inserted,
The edge of the through hole is shaped so that when the branch cable is pulled from the building in the direction of the trunk cable system, the cable portion of only the optical fiber main line can be preferentially cut over the other cable portions. Protective equipment characterized by being given. Said body is a substantially cylindrical shape having the through hole as a cylinder hollow, claim 1, wherein said slit is characterized by being applied to a side of the main body to extend along the axis of the through hole The protective device described. The protective device according to claim 2 , wherein the slit is formed to bend and extend on a side surface of the main body. The main body has a substantially thick plate shape, the through hole penetrates the main body in the thickness direction, and the slit extends along the axis of the through hole and is given from the side of the main body to the through hole. claim 1 Symbol placement of the protective device, characterized in that it is. The protective device according to claim 4 , wherein the slit is curved along the axis of the through hole. Protection device according to claim 5 Symbol mounting, characterized in that further have a supplementary portion extending connecting or sequentially with a right angle other predetermined angle to the body Protection device according to claim 6 Symbol mounting, wherein the supplementary part can be fixed to the outside through which has a mounting hole.