JPH0532966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Background and Objectives of the Invention] The present invention relates to an indoor wiring method, and more particularly to a method for rewiring using a cable buried directly in concrete.

The most common method of directly burying indoor wiring in concrete is to bury electrical conduits directly in concrete and run wires and cables through the conduits. The conduit and the wires/cables are manufactured separately, and the tedious work of running the wires/cables through the conduit is required, which requires a lot of man-hours. In addition, the conduit had to be much larger than the wires and cables for smooth wiring, which unnecessarily increased the wiring space.

In view of the drawbacks of conventional construction methods using electrical conduits,
A construction method using a so-called direct-buried concrete cable, in which the cable itself has a protective coating that can withstand shock during concrete placement, has been proposed and put into practical use.

According to this method of directly burying cables in concrete, the wiring space can be reduced to the size of the cable, and the man-hours are reduced to just burying the cables. However, the biggest drawback is that once the cables are buried, they are buried in concrete. Because it is integrated, it is difficult to rewire the cable itself or replace it in the event of damage, and it involves difficult construction work such as peeling off hardened concrete.

In view of the problems of the prior art described above, the present invention has been made to
It is an object of the present invention to provide a new method for rewiring a cable directly buried in concrete, which can be advantageously rewired using a cable directly buried in concrete.

[Summary of the invention]

The rewiring method for directly buried cables in concrete provided by the present invention is a solid structure with an inclusion between the external protective sheath and the cable core so that the cable core inside the external protective sheath can be extracted. Directly buried cables shall be rewired so that the external protective sheath is integrated with the concrete, and electric wires that do not have an external protective sheath will be connected to the cable core of the cable. By removing only the wires and inclusions, the electric wire for secondary wiring is passed through the external protective sheath that is integrated into the concrete and remains hollow and has not undergone any processing, and the electric wire and the hollow state are connected. It is characterized by the presence of a gap between it and the outer protective sheath.

〔Example〕

Hereinafter, the embodiment will be explained with reference to drawings.

FIG. 1 shows an example of an indoor wiring situation, and FIG. 2 shows a primary wiring cable used for the wiring.

The cable 1 is directly buried in the ceiling concrete 2 and wired, and is led into the joint box 3 buried in the ceiling concrete 2 to connect the light fixture 4.
It is also connected to the outlet box 7 of the wall board 6 by lowering it from the ceiling concrete 2 to the wall 5. Thus, the cable 1 has a cable core 12 which has a conductor 10 coated with an insulator 11.
, an external protective sheath 13 provided to surround this cable core 12 , and an inclusion 14 provided between this external protective sheath and the cable core 12 .
The inclusion 14 is made of a material, such as a rubber-like foam, which has a lubricant applied to its outer surface so that it can be separated from at least the outer protective sheath 13, or which is itself easily deformable. This allows the cable core 12 to be extracted together with the inclusion 14 even if the external protective sheath 13 is integrated and buried in concrete.

As described above, primary wiring is performed by directly burying the cable 1 in concrete, but it becomes necessary to change the wiring due to a subsequent increase in current carrying capacity. According to the present invention, wiring is changed using the cable 1 itself.

That is, for secondary wiring, the joint box 3 is opened to release the tip of the cable 1, and the outlet box 7 at the opposite terminal is opened to release the same terminal. After connecting the electric wire 20 to be newly wired to the cable core 12 at the cable terminal on the outlet box 7 side, the cable core 12 and the inclusion 14 are removed from the cable terminal side of the joint box 3, and the concrete is removed accordingly. The wires are successively drawn into the outer protective sheath 13 which remains in a hollow state and has not undergone any processing, and are thereby used for secondary wiring.

Figure 3 shows the cable structure when wiring is changed.
In a cable that has already been directly buried in concrete, an electric wire 20 for rewiring that does not have an external protective sheath is housed in an external protective sheath 13 that has become hollow by removing the cable core and inclusions. In this case, the external protective sheath 13 is
It is integrated with the poured concrete and maintains a hollow state, and a gap 21 exists between the external protective sheath 13 and the electric wire 20. Since this void 21 is formed when wiring is changed after concrete has already been placed, the external protective sheath 13 will not be crushed and can protect the electric wire 20 while maintaining its shape. can. Further, the presence of the void 21 makes the electric wire 20 less susceptible to strong impacts transmitted through the concrete, and the void serves as a cushion, so to speak, to reliably protect the electric wire 20. Direct-buried concrete cables have a solid structure with inclusions interposed in order to alleviate the impact during concrete placement, and these voids play the same role as the inclusions, which play a role in cushioning the impact after direct burial.

In the above case, even when the connection part 8 is provided in the middle as shown in FIG. 1, if the connection part 8 is made large enough to pass through the outer protective sheath 13, it can be pulled out including the connection part 8.

〔Effect of the invention〕

According to the direct-buried concrete wiring method of the present invention, which is constructed as described above, a direct-buried concrete cable that has already been directly buried in concrete is to be rewired, and is integrated into the concrete to maintain a hollow state and not have any problems. Because the cable core built into the unprocessed external protective sheath of the cable itself is used as a drag net to lead in and run the wire for rewiring that does not have an external protective sheath, it is not possible to directly bury it in concrete. This makes it possible to take advantage of the space-saving feature of cables, and to carry out predetermined wiring changes without destroying concrete.

Furthermore, in cables directly buried in concrete,
By removing the cable core and inclusions, the outer protective sheath becomes hollow, but is integrated with the concrete and maintains its hollow state.The wire for rewiring is routed with a gap left in the outer protective sheath.
The impact transmitted to the external protective sheath through the concrete is alleviated by the void, ensuring the protection of rewiring wires that do not have an external protective sheath, and is equivalent to a cable directly buried in concrete with a solid structure with an inclusion. You can enjoy the effects of

As described above, the wiring rewiring method of the present invention
This method provides a method for rewiring cables directly buried in concrete without impairing the usefulness of the cable, and is outstanding in terms of both workability and economy among this type of rewiring method.

[Brief explanation of drawings]

Figures 1 to 3 show an embodiment of the wiring rewiring method for directly buried cables in concrete according to the present invention, Figure 1 is an explanatory diagram showing an example of a wiring system, and Figure 2 shows the structure of a directly buried cable in concrete. FIG. 3 is a cross-sectional explanatory view showing the cable structure at the time of wiring replacement. In the symbols, 1 indicates a directly buried cable in concrete, 2 indicates a ceiling concrete, 12 indicates a cable core, 13 indicates an external protective sheath, 14 indicates an inclusion, 20 indicates an electric wire for rewiring, and 21 indicates a gap.

Claims (1)

[Claims] 1 A solid structure with an inclusion between the external protective sheath and the cable core so that the cable core inside the external protective sheath can be extracted, and the external protective sheath is directly buried so that it is integrated with the concrete. The cables that have been installed will be rewired, and a rewiring wire that does not have an external protective sheath will be connected to the cable core of the cable, and only the cable core and inclusions will be removed. An electric wire for rewiring is passed through an external protective sheath that is integrally maintained in a hollow state and has not undergone any processing, and a gap is created between the electric wire and the hollow external protective sheath. A special feature is the rewiring method for directly buried cables in concrete.