151 Scope and composition of lightning protection system
151.1 Scope of application
1. Buildings and structures with electrical and electronic equipment installed that require protection from lightning or are 20 m or higher in height from the ground.
2. Low voltage electrical and electronic equipment
3. High-voltage and extra-high-voltage electrical equipment
151.2 Composition of lightning protection system
1. External lightning protection system to protect objects from direct lightning strikes
2. Internal lightning protection system to protect objects from indirect and induced lightning.
151.3 Lightning protection system rating selection
1. Lightning protection system of 152.2.1 shall be installed where necessary according to lightning protection system level.
2. The lightning protection system grade is selected according to the lightning protection level according to KS C IEC 62305-2 (Lightning Protection System - Part 2: Risk Management) depending on the characteristics of the object. However, lightning protection systems installed in hazardous materials manufacturing plants, storage sites, and treatment plants must be of class II or higher.
152 External lightning protection system
152.1 Lightning protection systems for buildings and structures to protect electrical equipment
152.1.1 Air-termination system
1. When selecting an air-termination system, it shall be as follows.
go. It must be installed with one or a combination of the elements of lancet, horizontal conductor, and mesh conductor.
me. Air-termination system materials are listed in Table 6 (Materials, shapes and minimum cross-sectional areas of air-termination conductors, lightning rods, and ground-entry collapse down-conductors) of KS C IEC 62305-3 (Lightning protection systems - Part 3: Physical damage to structures and hazards to life). Follow.
all. Natural structural members can be used as components.
2. The arrangement of the air-termination system is as follows.
go. It must be arranged using one or a combination of the protective angle method, rotating sphere method, and mesh method. However, the maximum values of the protection angle, sphere radius, and mesh size of the lightning protection system are Table 2 (Rotating sphere by lightning protection system class) of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and risk to life). radius, mesh dimensions and maximum protection angle) and Figure 1 (protection angle by lightning protection system class).
me. Prioritize placement on sharp parts and corners of buildings and structures.
3. The air-termination system for side lightning protection of buildings and structures exceeding 60 m in height must be installed as follows.
go. Install to protect the upper floor and the equipment installed in this area. However, if the height of the upper part exceeds 60 m, it is limited to 20% of the total height from the top.
me. It should be placed first in corners, edges, and important protrusions, and should be of lightning protection system grade Ⅳ or higher.
all. When using natural structural members, follow the minimum thickness in Table 3 (Minimum thickness of metal plate or metal pipe for air-termination system) of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and risk to life). .
la. The air-termination part connects or installs down-conductors to the steel frame of the structure or to the down-conductors of natural elements such as metal in electrically connected steel concrete.
4. The facilities of the air-termination system that are not separated from buildings and structures are subject to the following.
go. If the roof finishing material is made of non-combustible material, it can be installed on the roof surface.
me. If the roof finishing material is made of a highly flammable material, install it at a distance from the roofing material as follows.
(1) In case of thatched roof or similar, 0.15 m or more
(2) 0.1 m or more for other combustible materials.
5. When using natural structural members such as metal plates or metal pipes constituting a building or structure as an air-termination part, the third “C” condition must be satisfied.
152.1.2 Down-conductor system
1. Connecting the air-termination system and the grounding system is as follows.
go. Multiple down-conductors must be configured in parallel. However, an exception is made in cases where the lightning protection system is separate from the building or structure.
me. Ensure that the path length is minimal.
all. Down-conductor system materials are listed in Table 6 (Materials, shapes and minimum cross-sectional areas of air-termination conductors, lightning rods, and ground-entry collapse down-conductors) of KS C IEC 62305-3 (Lightning protection systems - Part 3: Physical damage to structures and hazards to life). Follow.
2. The arrangement method is as follows.
go. In case of a lightning protection system separated from buildings and structures
(1) The path of the lightning current must be ensured so that it does not contact the object to be protected.
(2) When installed on separate pillars, more than 1 set of down-conductors shall be installed for each pillar.
(3) In the case of a horizontal conductor or mesh conductor, more than one set of down-conductors should be installed for each supporting structure.
me. In case of a lightning protection system that is not separated from buildings or structures
(1) If the wall is made of non-combustible materials, it can be installed on the surface or inside the wall. However, if the wall is made of combustible material, the separation should be at least 0.1 m, and if separation is not possible, the cross-sectional area of the conductor should be at least 100 ㎟.
(2) The number of down-conductors shall be 2 or more.
(3) Arrange them at equal intervals as much as possible around the projection of buildings and structures subject to protection. However, priority should be given to installation on exposed corners.
(4) The maximum spacing of parallel down-conductors is 10 m for classes I and II, 15 m for class III, and 20 m for class IV, depending on the lightning protection system class.
3. To ensure electrical continuity between the air-termination system and the earth electrode system, facilities must be installed according to the following.
go. The path should be installed straight and vertically over the shortest possible distance, but should not form a loop, and should not be installed inside an eaves or vertically installed gutter.
me. When natural components are used, electrical continuity must be guaranteed. However, for electrical continuity suitability, the direct current electrical resistance between the uppermost part of the relevant metal member and the ground level is set to 0.2 Ω or less.
all. A test connection point must be installed at the connection between the down-conductor and the ground electrode system close to the ground electrode system. This connection point must always be closed and can only be opened with a tool, etc. when measuring. However, cases where natural components are used are excluded.
4. Natural structural members used as down-conductors are as follows.
go. The electrical continuity and durability of each part are certain and exceed the value specified for the down-conductor in item 1.
me. Metal structures such as structures with electrical continuity (steel frame, rebar, etc.)
all. Interconnected steel structures such as structures
la. Metal pipes whose dimensions comply with the requirements for down-conductors or whose thickness is not less than 0.5 mm, as decorative wall materials, side rails and auxiliary materials for metal decorative walls. However, connect so that vertical electrical continuity is maintained.
mind. When interconnected reinforcing bars, steel frames, etc. of structures are used as down-conductors, horizontal ring conductors do not need to be installed.
bar. Connection of down-conductors is in accordance with 152.1.4.
152.1.3 Earth electrode system
1. The ground electrode system for discharging lightning current to the ground is as follows.
go. It must be installed with one or a combination of horizontal or vertical grounding electrodes (type A), ring conductor grounding electrodes, or basic grounding electrodes (type B).
me. The material of the earth electrode system follows Table 7 (material, shape and minimum dimensions of the earth electrode) of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and hazards to life).
2. The arrangement of the earth electrode system is as follows.
go. At least two horizontal or vertical grounding electrodes (type A) must be placed at equal intervals, and should be placed at equal intervals, as shown in Figure 3 of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and hazards to life) (each LPS class). The minimum length of the earth electrode (minimum length of the earth electrode) shall be greater than the minimum length according to the ground resistivity for each lightning protection system class. However, the conversion rate based on installation direction is 1.0 for horizontal and 0.5 for vertical.
me. The ring conductor grounding electrode or basic grounding electrode (type B) has an average radius converted to the area of the grounding electrode as shown in Figure 3 of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and risk to life) (of each grounding electrode by LPS grade). (minimum length), and if the average radius is less than the minimum length, an additional horizontal or vertical buried ground electrode of the corresponding length must be installed. However, the number of additional horizontal or vertical grounding electrodes should be at least two.
all. If the grounding resistance of the earthing electrode system is 10Ω or less, it can be set below the minimum length despite the second “A” and “B”.
3. The ground electrode should be installed according to the following.
go. It must be buried at a depth of 0.75 m or more from the ground surface. However, if necessary, it can be adjusted to a depth that takes into account the depth of freezing in the relevant area.
me. In cases where the site is a rocky area with high earth resistance or where buildings and structures frequently use electronic communication systems, a ring conductor ground electrode or basic ground electrode is used.
all. The earth electrode material must be free from environmental pollution and corrosion problems on the ground.
la. Natural structural members such as interconnected steel bars or metal underground structures within a reinforced concrete foundation can be used as ground electrodes.
152.1.4 Parts and connections
1. The minimum cross-sectional area according to the shape of the material is Table 6 of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and risk to life) (Materials and shapes of air-termination conductors, lightning rods, and ground-entry collapse down-conductors) and minimum cross-sectional area).
2. Fixing parts must be made of materials that comply with KS C IEC 62561-4 (Lightning Protection System Components (LPSC) - Part 4: Requirements for conductor fixtures).
3. The connection must be made by a method suitable for the field conditions, such as welding, crimping, sealing, screwing, or bolting. The connection of the reinforcement must be in accordance with KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to the structure) and risk to life) in accordance with E.4.3.3 (welding or clamping connection to steel reinforcement bars).
4. The performance of connecting materials used in lightning protection systems is in accordance with KS C IEC 62561-1 (Lightning Protection System Components (LPSC) - Part 1: Requirements for connecting materials).
152.2 Lightning protection system for high-voltage and extra-high-voltage electrical equipment
152.2.1 Protection against direct lightning of externally installed electrical equipment
1. Lightning protection systems for high-voltage and extra-high-voltage electrical equipment shall comply with 152.1.
2. If there is an external lightning shield, it must be grounded.
3. Steel structures, etc. can be used as natural down-conductors.
153 Internal lightning protection system
153.1 Lightning protection system for protecting electrical and electronic equipment
153.1.1 Protection against lightning strikes of electrical and electronic equipment
1. Protection against lightning surges is provided by one or more of the following.
go. Grounding/bonding
me. Magnetic shielding and surge inflow path shielding
all. Installation of surge protection device
la. Isolated interface configuration
2. Protection against lightning surges in electrical and electronic equipment is as follows.
go. Lightning protection zones are classified according to 4.3 (Lightning protection zone (LPZ)) of KS C IEC 62305-4 (Lightning protection system - Part 4: Electrical and electronic systems inside structures).
me. A surge protection device in accordance with KECG 9102 (Technical Guidelines for SPD Installation of Low Voltage Electric Equipment) must be installed at the boundary of the lightning protection area.
all. When separate structures are connected by power lines or signal lines, each lightning protection area is connected to each other in the method specified in 153.1.3, 2, “C”.
3. When selecting electrical and electronic equipment, the rated impulse withstand voltage is “Ⅳ.” of KECG 9102 (Technical Guidelines for SPD Installation of Low Voltage Electric Equipment). It must be greater than the value specified in “Rated impulse withstand voltage of low-voltage electrical equipment.”
153.1.2 Electrical insulation
1. Electrical insulation between air-termination or down-conductors and metal parts of buildings or structures is in accordance with Annex A (air-termination system) of KS C IEC 62305-3 (Lightning protection systems - Part 3: Physical damage to structures and hazards to life). It is set as the separation distance according to the arrangement.
2. Notwithstanding Article 1, if the building or structure is made of metal or has a reinforced concrete structure with electrical continuity, electrical insulation does not need to be considered.
153.1.3 Protection by grounding and bonding of electrical and electronic equipment
1. Grounding and bonding to protect electrical and electronic equipment are as follows.
go. Grounding must be provided to discharge lightning surge current to the ground.
me. Bonding must be established to resolve the potential difference and reduce the magnetic field.
2. Earth electrodes, other than those specified in 152.1.3, shall comply with the following.
go. The grounding of electronic and communication equipment (or something similar) is done using a ring conductor grounding electrode or basic grounding electrode.
me. When grounding is done with a ring conductor grounding electrode or basic grounding electrode, a mesh grounding network must be installed at intervals of less than 5 m. However, if the basic reinforced concrete floor is well connected to each other and the reinforcing bars form a mesh network, or if they are connected to the ground electrode every 5 m or less, it is considered a ground electrode.
all. When multiple buildings, structures, etc. are each grounded, and there are cables (or multiple cables arranged on the same path) inside the concrete duct or metal piping connecting each part, each ground must be installed in parallel. It must be connected with a conductor. However, in the case of a shielded cable, the shielded wire must be equipotentially bonded to each grounding system at both ends.
3. If it is necessary to eliminate dangerous potential differences and reduce magnetic fields in electronic and communication equipment (or similar devices), an equipotential bonding network as follows must be installed.
go. Equipotential bonding networks are installed by integrating the conductive parts of buildings and structures or parts of internal facilities.
me. The equipotential bonding network is installed with a mesh width of less than 5 m, and the structure and the metal parts inside the structure are connected in multiple ways. However, when metal parts or conductive equipment passes the boundary of the lightning protection area, they are bonded directly or through a surge protection device.
all. The equipotential bonding of the conductive part is radial, mesh, or a combination thereof.
153.1.4 Surge protection device facility to protect electrical and electronic equipment
1. Surge protection devices must be installed on electric lines, communication lines, etc. installed in the following locations.
go. For buildings and structures, one or more lightning protection zones are established, and surge protection devices are installed on the incoming lines of each lightning protection zone.
me. Other surge protection device facilities are in accordance with Ⅴ. of KECG 9102 (Technical Guidelines for SPD Installation of Low Voltage Electric Equipment). 1. (Decision on whether to install SPD)
2. Selection of surge protection device is as follows.
go. Protection of electrical equipment is based on KS C IEC 61643-12 (Low-voltage surge protection devices - Part 12: Surge protection devices connected to low-voltage distribution systems - Selection and application guidelines) and KS C IEC 60364-5-53 (Building electrical equipment - Part 5-53: Selection and construction of electrical equipment - Insulation, switching and control) and KS C IEC 61643-11 (Low-voltage surge protection devices - Part 11: Low-voltage surge protection devices in low-voltage power systems - Requirements and The product must be used according to the test method.
me. Protection of electronic and communication equipment (or similar devices) follows KS C IEC 61643-22 (Low voltage surge protection devices - Part 22: Surge protection devices for communication and signal network connections - Selection and application guidelines).
3. In the case of underground low-pressure water hydrants, if the impulse withstand voltage for each overvoltage category of the electrical and electronic devices installed inside meets the specified value, the surge protection device can be omitted.
153.2 Lightning protection system equipotential bonding
153.2.1 General
1. The conductor part of the external lightning protection system must be subjected to equipotential bonding with the following metallic parts.
go. Metal equipment (according to 153.2.2)
me. External conductive parts connected to the structure (according to 153.2.3)
all. Internal lightning protection system (according to 153.1.3)
2. Interconnection of equipotential bonding is as follows.
go. Places where electrical continuity cannot be secured through bonding due to natural components are connected with bonding conductors.
me. In places where direct connection with bonding conductors is not suitable or permitted, connect with a surge protection device.
3. The material and minimum cross-sectional area of the equipotential bonding parts are in accordance with “5.6 Materials and Dimensions” of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and hazards to life) and Table 1 (Lightning protection level and lightning protection system rating) relationship between them).
4. For other equipotential bonding, refer to “6.2 Lightning equipotential bonding” of KS C IEC 62305-3 (Lightning protection system - Part 3: Physical damage to structures and risk to life) and commentary Ⅲ of KECG 9103 (Technical guidelines on equipotential bonding) .(Equipotential bonding for lightning protection).
153.2.2 Equipotential bonding of metal equipment
1. If the external lightning protection system is independent and separated from the building or structure to be protected, equipotential bonding must be installed near the ground level.
2. When the external lightning protection system is connected to the building or structure to be protected, the equipotential bonding must be connected at the following location.
go. It must be done at a location near the foundation or ground level. The equipotential bonding conductor must be connected to the equipotential bonding bar, and the equipotential bonding bar must be connected to the grounding system. It must be easy to inspect.
me. In cases where it is impossible to secure a safe separation distance according to the insulation requirements, the lightning protection system and the conductive parts of the building, structure, or internal equipment must be equipped with equipotential bonding, and must be connected directly or, in the case of a live part, via a surge protection device. However, when using a surge protection device, the protection level must be lower than the impulse withstand voltage of the device in the protection zone.
3. Equipotential bonding of buildings and structures must be done as follows.
go. If the height is over 20 m, install a toroidal equipotential bonding bar on the ground surface and at a height of 20 m, or install two or more equipotential bonding bars sufficiently spaced apart and connect them to each other.
me. If the height is over 30 m, install a toroidal equipotential bonding bar repeatedly for equipotential bonding at the ground surface and at a point of 20 m in height and every 20 m height above, or install two or more equipotential bonding bars sufficiently spaced apart and connect them to each other.
4. Equipotential bonding connections should be made as straight as possible.
153.2.3 Equipotential bonding of incoming equipment
1. Equipotential bonding for the conductive parts of equipment coming from the outside to the inside of a building or structure is as follows.
go. Equipotential bonding is performed in accordance with 143.1.1 near the inlet.
me. The power line is equipped with equipotential bonding via a surge protection device.
all. Communication and control lines are equipotential bonded directly or through surge protection devices to prevent dangerous potential differences between them.
2. In the case of low-voltage power supply, equipotential bonding must be done at a point near the inlet switchboard or distribution box, and the bonding bar must be connected to ground with a bonding conductor of a short path.
3. If the connection part of the gas pipe or water pipe is an insulator, equipotential bonding must be performed using an appropriate method (using insulation dissipation gap, etc.) with the consent of the relevant facility supplier.
4. If the low-voltage grounding system is a TN system, the protective conductor (or protective conductor for neutral conductor) must be connected to the bonding bar directly or through a surge protection device. However, if the power line or communication line is shielded or wired within a metal pipe, the shielding layer or metal pipe must be bonded.
153.2.4 Equipotential bonding bar
1. The installation location should be such that it can be connected to the grounding system through a short path. In the case of a low-voltage power receiving system, it should be installed on an internal wall near the ground surface close to the main switchboard.
2. It must be connected to the grounding system (annular grounding electrode, basic grounding electrode, grounding reinforcement of the structure, etc.) through a short path.
3. If the external conductive parts, power lines, and communication lines have different entry points, multiple equipotential bonding bars can be installed.
4. If the building or structure is for electronic or communication equipment (or similar) that requires a low level of surge withstand voltage, the installed internal ring conductor must be connected to reinforcement every 5 m.