An introduction to the lightning protection design of buildings based on the basic GB50057 lightning protection standard
May 23, 2022
An introduction to the lightning protection design of buildings based on the basic GB50057 lightning protection standard
1. In the basement or ground floor of the building, those objects should be connected to the lightning protection device for lightning protection equipotential connection.
answer:
1) Building metal body.
2) Metal device.
3) In-building systems.
4) Metal pipelines entering and leaving the building.
Analysis of the first paragraph of Article 4.1.2 of GB 50057-2010 "Code for Design of Lightning Protection of Buildings"
2. For the first type of lightning protection buildings, when the buildings are higher than 30m, those measures to prevent side strikes should be taken.
answer:
1) From 30m onwards, horizontal lightning strips should be set up around the building at intervals of not more than 6m and should be connected with down conductors.
2) Large metal objects such as railings, doors and windows on the outer walls of 30m and above should be connected to the lightning protection device.
Analysis of Article 7 of Article 4.2.4 of GB 50057-2010 "Code for Design of Lightning Protection of Buildings"
3. When a lightning protection building has first, second and third types of lightning protection buildings, its lightning protection classification and lightning protection measures should comply with those regulations.
answer:
1) When the area of the first type of lightning protection buildings accounts for 30% or more of the total area of the building, the building should be determined as the first type of lightning protection buildings.
2) When the area of the first type of lightning protection building part accounts for less than 30% of the total area of the building, and the area of the second type of lightning protection building part accounts for 30% or more of the total building area, or when the two The area of some lightning protection buildings is less than 30% of the total area of the building, but the sum of their areas is greater than 30%, the building should be determined as the second type of lightning protection buildings. However, the protection measures of the first type of lightning protection buildings should be taken for the lightning protection induction and lightning surge protection of the first type of lightning protection buildings.
3) When the sum of the area of the first and second types of lightning protection buildings is less than 30% of the total area of the building, and it is impossible to be directly struck by lightning, the building can be determined as the third type of lightning protection buildings; For the lightning-proof induction and lightning-surge intrusion of the first and second types of lightning protection buildings, protection measures of their respective categories should be taken; when they may be directly struck by lightning, lightning protection measures should be taken according to their respective categories.
Analysis of GB 50057-2010 "Code for Lightning Protection Design of Buildings" 4.5.1
4. Festive lanterns, aviation obstacle signal lights and other electrical equipment and lines fixed on buildings should take corresponding measures to prevent the intrusion of lightning surges according to the lightning protection category of the building, and should comply with those regulations.
answer:
1) Electrical equipment without metal casing or protective net cover should be within the protection range of the air-termination device.
2) The distribution line drawn from the distribution box should wear steel pipes. One end of the steel pipe should be connected to the distribution box and PE line; the other end should be connected to the shell and protective cover of the electrical equipment, and should be connected to the roof lightning protection device nearby. When the steel pipe is disconnected in the middle due to connecting equipment, a jumper shall be provided.
3) In the distribution box, a surge protector with class II test shall be installed on the power supply side of the switch, and its voltage protection level shall not be greater than 2.5kV, and the nominal discharge current value shall be determined according to the specific situation.
Analysis of GB 50057-2010 "Code for Design of Lightning Protection of Buildings" 4.5.4
5. Anti-contact voltage should comply with those regulations.
answer:
1) The steel bars used to connect the building’s metal frame and the building are electrically connected and consist of no less than 10 columns. .
2) The resistivity of the surface layer within 3m of the downconductor shall not be less than 50kΩm, or a 5cm thick asphalt layer or a 15cm thick gravel layer shall be laid.
3) For exposed down-conductors, the conductors below 2.7m from the ground shall be isolated by an insulating layer with a resistance of 1.2/50μs impulse voltage of 100kV, or by a cross-linked polyethylene layer with a thickness of at least 3mm.
4) Use guardrails and warning signs to minimize the possibility of contacting down conductors.
Analysis of paragraph 1 of Article 4.5.6 of GB 50057-2010 "Code for Lightning Protection Design of Buildings"
6. The anti-step voltage should meet one of the following requirements:
answer:
1) The steel bars used to connect the building’s metal frame and the building are electrically connected and consist of no less than 10 columns. .
2) The resistivity of the surface layer within 3m of the downconductor shall not be less than 50kΩm, or a 5cm thick asphalt layer or a 15cm thick gravel layer shall be laid.
3) Use a mesh grounding device to perform equalization potential treatment on the ground.
4) Use guardrails and warning signs to minimize the possibility of entering the ground within 3m from the down conductor.
Analysis of paragraph 2 of Article 4.5.6 of GB 50057-2010 "Code for Design of Lightning Protection of Buildings"
7. For the second and third types of lightning protection buildings, when the size of the isolated metal objects on the roof that is not protected by the air-termination device does not exceed a certain value, additional protection measures may not be required:
answer:
1) No more than 0.3m above the roof plane.
2) The total surface area of the upper layer shall not exceed 1.0m2.
3) The length of the upper surface shall not exceed 2.0m.
Analysis of the first paragraph of Article 4.5.7 of GB 50057-2010 "Code for Design of Lightning Protection of Buildings"
8. The specially laid air-termination should be composed of one or more ways.
answer :
1) Independent air terminals.
2) Overhead air-termination wire or overhead air-termination net.
3) Air-termination poles, air-termination strips or air-termination nets installed directly on buildings.
Analysis of GB 50057-2010 "Code for Lightning Protection Design of Buildings" 5.2.11
9. Basic regulations for lightning protection against electromagnetic pulses.
answer:
When the scale and specific location of the electronic system are not known at the design stage of the project, if it is expected that there will be electrical and electronic systems that require lightning protection against electromagnetic pulses in the future, the metal supports, metal frames or Natural components such as steel bars of reinforced concrete, metal pipes, protective grounding systems for power distribution, etc., and lightning protection devices form a grounding system, and equipotential bonding plates should be embedded where necessary.
When the power supply adopts the TN system, the power distribution lines and branch lines in the building from the main distribution box of the building must use the TN-S system.
Analysis of GB 50057-2010 "Code for Design of Lightning Protection of Buildings" Section 6.1