JP2946223B2 - Laying of communication and power cables in buildings - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for laying a communication cable, a power cable, and the like in a building.

2. Related Art Problems to be Solved by the Related Art and Invention In recent years, with the digitization of communication devices, the resistance to overvoltage has been reduced, and there have been cases where the communication devices are damaged by direct lightning strikes on buildings.

In order to prevent such a failure, it is necessary to suppress the penetration of a lightning surge current into the communication device.

However, in the past, importance was placed on the arrangement of communication devices from the viewpoint of effective use of the floor space in a building, and communication cables and power cables in the building were often laid near the outer peripheral wall or pillar of the building.

On the other hand, when a lightning strike occurs directly on a building, it is said that a large amount of surge current flows on the rooftop and outer peripheral wall of the building, but from the viewpoint of protecting the communication device against the induced current generated by this surge current. Laying methods of communication cables and power cables have not been considered.

For this reason, when a direct lightning strike to a building occurs, lightning surge current flowing through the building rebar and steel frame generates induced current in the communication cable and power cable, which invades the communication device and causes the communication device to fail. There has been a problem that failures such as malfunctions and dielectric breakdown occur.

 Fig. 3 shows the current distribution of the pillars and beams of the building during a direct lightning strike.

The numerical values in the figure are the ratio of the lightning surge current flowing.
From this figure, it can be seen that in the case of a direct lightning strike to the building, the surge current flows unbalanced on the roof and the outer wall of the building, and hardly flows in the center of the building.

 FIG. 4 shows the electromagnetic distribution on the floor during a direct lightning strike.

This figure shows the magnetic field strength when a surge current of 50 A evenly flows through the square pillar on the floor. It can be seen that the place where the magnetic field strength is strong is near the pillar of the building.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress an induced current from flowing to a communication device installed in a building due to a lightning surge flowing through the building due to a direct lightning strike on the building.

Means for Solving the Problems The present invention relates to a method of vertically laying a communication cable or a power cable connecting a plurality of communication devices in a building in a building in a vertical direction. It is insulated from the reinforcing bar or steel frame of the ceiling and the outer peripheral wall of the top floor of the building and the column, and is electrically connected to the reinforcing bar or steel frame of each relevant floor of the building in a location on the center floor where separation guidance does not occur. Install metal cable talc that reaches the floor of the lowest floor, or cable that reaches the floor of the lowest floor that is insulated from the ceiling and outer walls of the top floor of the building consisting solely of insulation and the reinforcing bars or steel frames of the columns. A duct is installed, and a communication cable or a power cable is laid in the metallic and insulating cable duct.

Effect of the Invention According to the present invention, the communication cable and the power cable are arranged at positions where there is no influence from the electromagnetic field by the cable duct arrangement having the above-described configuration. Therefore, even if there is a direct lightning strike in the building, the surge current flowing to the communication device can be suppressed. Can be.

Embodiment 1 Embodiment 1 FIG. 1 shows a specific first embodiment of a method for laying a cable duct in a building (hereinafter referred to as a laying method) according to the present invention.
(A) is a plan view, and (B) is a front view.

 The configuration of the present invention will be described.

In the figure, 1 indicates an outer peripheral wall, 2 indicates a pillar, 3 indicates an inner wall, 4 indicates a cable duct, 5 indicates a communication cable, 6 indicates a communication device, and 7 indicates a cable duct laying range.

According to the present invention, the cable duct 4 is insulated from the ceiling on the top floor by the insulator 8 and is laid vertically in the building at a position away from the outer peripheral wall 1 and the pillar 2 of the building. In FIG. 1, the laying range 7 is indicated by oblique lines.

The shape of the cable duct is cylindrical or rack-shaped, and the material is metal or an insulator. Communication device 6
Communication cable, power cable or ground wire 5 to be connected to
Is laid in the cable duct 4. When laying a metal cable duct, a reinforcing rod or a steel frame is electrically connected to the cable duct on each floor of the building so that a potential difference does not occur between the floor and the floor. In the case of a metallic cable duct, it can be used as a ground conductor. If the pillar 2 and the laying area are separated from each other by about 2 m, the guide to the cable laid in the cable duct is sufficiently reduced, and the influence on the communication device is suppressed.

Embodiment 2 FIG. 2 shows a second embodiment of the laying method of the present invention, (a) shows a plan view, and (b) shows a front view.

In the figure, the same reference numerals as those in FIG. 1 indicate the same parts and the same parts.

In the present embodiment, the cable duct 4 is laid at a position along the inner wall 3 of the building and at a position away from the pillars 2 at both ends of the inner wall 3. In this case, since there is no cable duct at the center of the floor, the floor can be used effectively.

In addition, even in the case of a direct lightning surge, since it is away from the building outer wall or pillar where a large current flows, induced current to a communication cable, a power cable, or the like can be suppressed.

Advantageous Effects of the Invention As described above, the present invention arranges a cable duct at a position apart from the outer wall where a direct lightning surge current flows or near a column having a strong electromagnetic field strength, and includes a communication cable, a power cable, a ground conductor, etc. therein. There are the following advantages by laying.

Surge current flowing to the communication device in the building due to direct lightning strike on the building is suppressed, and an effect is produced that can suppress occurrence of troubles such as malfunction of the communication device and insulation breakdown.

An electromagnetic field from outside the cable duct generates an induced voltage and current in the communication cable and the power cable installed in the cable duct. On the other hand, if the cable duct is configured to be surrounded by a metal plate and a tube that is electrically connected from the top floor to the bottom floor of the building, the cable duct can function as a shielding layer, and a shielding effect can be expected. Guide to the cable to be laid. Another advantage is that the cable can be easily pulled out. In addition, when such an electrically connected structure is installed in the vertical direction of a building, it can be used as a ground conductor, and the cross-sectional area of the metal pair (or The surface area per unit length) is sufficiently large, so that the resistance is low, which is very convenient as a ground conductor.

When the cable duct is made of an insulator, the shielding effect is naturally zero. In addition, since an electric current does not flow through the cable duct even if the insulator is wrong, the influence of noise flowing through the cable duct is eliminated as compared with a metal cable duct.

[Brief description of the drawings]

FIG. 1 is a specific first embodiment of a method for laying a cable duct in a building according to the present invention, (a) is a plan view, (b) is a front view, and FIG. 2 is a second embodiment of the present invention. FIG. 3 (a) is a plan view, FIG. 3 (b) is a front view, FIG. 3 is a distribution diagram of a direct lightning surge current flowing through a building, and FIG. Show. 1: outer wall, 2: pillar, 3: inner wall, 4: cable duct, 5: communication cable, power cable, ground wire, etc., 6: communication device, 7: cable duct laying range, 8: insulator, 9: steel frame.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Minoru Ota 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References Masaharu Sato Two other people, "Direct hit of telephone office lightning surge Examination of distribution ", Technical Report of the Institute of Electronics, Information and Communication Engineers (EMC J89-14), May 19, 1989, Vol. 89, No. 44, p. 41-48 (58) Field surveyed (Int. Cl. ⁶ , DB name) H02G 3/00

Claims (2)

(57) [Claims] In a method of vertically laying a communication cable or a power cable for connecting a plurality of communication devices in a building in a building in a vertical direction, the communication cable or the power cable is separated from a reinforcing bar or a steel frame of an outer peripheral wall and a pillar of the building and does not cause an induction obstacle. In the center floor, the top floor of the building, the outer peripheral wall and the reinforcing bars or steel frames of the columns are insulated from the reinforcing bars or steel frames of the columns, and are electrically connected to the reinforcing bars or steel frames of each relevant floor of the building. Laying a communication cable or a power cable in a building, comprising laying a metal cable tact that reaches a predetermined distance, and laying a communication cable or a power cable in the cable duct. 2. A method for vertically laying a communication cable or a power cable for connecting a plurality of communication devices in a building in a building in a vertical direction, wherein the communication cable or the power cable is separated from a reinforcing bar or a steel frame of an outer peripheral wall and a pillar of the building and does not cause an obstacle. A cable duct that is insulated from the reinforcing steel or steel frame of the ceiling and outer peripheral walls and columns of the top floor of the building consisting solely of insulation and that reaches the floor of the lowest floor is installed in the center floor. Laying a communication cable or a power cable in a building characterized by laying a communication cable or a power cable in a building