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The last edit to this post was made by hesonchang214 on 2019-8-24 at 09:43. 1. Issues related to the installation of lightning protection systems: Article 12.1.4 of the Civil Code specifies that new construction projects should make use of the building’s metal conductors as part of the lightning protection system wherever possible. However, in practical design, some designers still use traditional methods and install dedicated lightning protection devices on buildings. Obviously, compared to traditional design methods, using the steel reinforcement in a building as a lightning protection device is safer, more reliable, and aesthetically pleasing. Since the rebar throughout the entire building is connected together during construction, a Faraday cage is naturally formed. This allows for a better balance of electric potentials inside the building, resulting in an effective voltage equalization effect that in turn provides better protection for the equipment and people inside the building. In practical design, it is important to note that when using the rebar in a building’s columns as down conductors, the following rules must be followed as specified in the codes: (1) When the diameter of the rebar is 16 mm or more, two bars should be used as one set of down conductors ； (2) When the diameter of the reinforcing bars is 10 mm or more, four reinforcing bars shall be used as a group for down conductors. The rebar in the columns and foundations that are to be utilized should be weldable, so as to form an electrical unity. 2. Issue of reserved external connections for lightning protection down conductors: Article 12.8.6 of the Civil Code stipulates that when using the rebar in building columns as down conductors, a D12mm or 40mm×4mm galvanized conductor should be welded at a depth of 0.8m to 1m below the outdoor ground level; this conductor must extend outside the building at a distance of no less than 1m from the exterior wall surface. In actual design work, many designers overlook this requirement and fail to specify it in the building electrical design drawings. Through the study and understanding of the specifications and explanatory texts, the author believes that in order to better dissipate lightning current, reduce the loading on the foundation, thereby lowering the heat generated in the foundation’s rebar and ensuring the safety of the foundation. At the same time, in order to create favorable conditions for installing additional grounding electrodes when the grounding resistance value of the entire building does not meet the specified requirements, designers should carry out the design in accordance with the relevant standards. 3. Preventing the intrusion of lightning waves: According to research, accidents caused by lightning waves invading high-voltage areas along low-voltage overhead lines account for over 70% of all lightning-related incidents. These incidents also result in the greatest losses in terms of human casualties and equipment damage; therefore, preventing the intrusion of lightning waves is an important aspect of lightning protection measures. In practical design, designers generally pay attention to protection against direct lightning strikes, but often give insufficient attention to measures to prevent the intrusion of lightning waves. To prevent lightning waves from intruding, designers should carry out the design in accordance with Article 12.5.6 of the Civil Code. For cable entries and exits, the metal sheath and steel pipes of the cables should be connected to the grounding of the electrical equipment at the entry and exit points. Lightning arresters should be installed at the entrances and exits, and connected to the iron feet of the insulators in order to be linked to the grounding system of the electrical equipment. This is because a discharge protection gap is formed between the insulator foot and the conductor, with a discharge voltage of around 40 kV; this value is sufficient to protect human safety, but it is not enough to protect low-voltage electrical equipment and circuits. According to IEC standards, the impulse voltage tolerance for low-voltage electrical equipment and circuits in indoor environments is 6 kV. The use of valve-type surge arresters helps to reduce the voltage difference between the exposed conductive parts and other conductive components of the electrical equipment, thereby ensuring its safe operation. 4. Issues related to the management of building lightning protection systems: Many people, especially the management personnel of some users, believe that once a building is equipped with a lightning protection system, it is completely safe. It's a misunderstanding. The lightning protection safety level of lightning protection devices is not 100%. Article 12.1.5 of the Civil Code states that the installation of lightning protection devices in accordance with these specifications will prevent or significantly reduce damage caused by lightning, but it cannot guarantee absolute safety. Article 12.9.12 further states that the grounding resistance of lightning protection devices should take into account the effect of dry soil conditions during the thunderstorm season. Therefore, the author believes that designers should incorporate the aforementioned provisions of the “Civil Code” in their design drawings. Users are reminded that maintenance and management of the building’s lightning protection systems should be strengthened; these systems should be inspected before the start of each thunderstorm season, and their grounding resistance should be checked again during the period when the soil is still dry before the rainy season arrives. Any damaged parts of the lightning protection system must be identified and repaired promptly, as failing to do so can be even more dangerous than not having such a system at all. This is because buildings equipped with lightning protection systems are more likely to be struck by lightning compared to those without such systems. 5. Issues related to the selection and installation of sockets: In building electrical installation projects, incorrect selection of sockets occurs from time to time. The author analyzes two cases of incorrect socket selection identified during project inspections as follows: In Case 1, a production workshop was originally designed to use 15A three-phase four-pin sockets; however, since the contractors could not obtain such sockets at that time, they replaced them with 15A single-phase three-pin sockets. This practice poses the following risks: (1) The safe operating voltage for single-phase sockets is generally no more than 250V, whereas the operating voltage for three-phase electrical equipment is 380V. When single-phase three-prong sockets are used with three-phase equipment, they are prone to breakdown and short circuits, thereby threatening the safety of such equipment ； (2) Single-phase three-pin sockets used to replace the power sockets of three-phase electrical equipment cannot be equipped with a neutral protection wire (PE); therefore, in the event of leakage from the enclosure of such electrical equipment, it poses a risk of electric shock to the operators ； (3) The persons who use the socket are not limited to the maintenance electricians in that production workshop; however, others who are unaware of the installation details of the electrical sockets in the workshop may mistakenly assume that this alternative socket is a power socket for single-phase devices, and plug single-phase devices into it for use. In such cases, since the neutral and ground terminals of this socket are actually connected to the phase line, the single-phase device (including its casing) comes under the influence of the dangerous 380V voltage, resulting in equipment damage and electric shock injuries or deaths. In another example, a laboratory was originally designed to use 15A single-phase three-pin sockets, but since the installers could not obtain those sockets at the time, they used 15A three-phase four-pin sockets as a substitute. Replacing a single-phase three-pin socket with a three-phase four-pin socket does not pose a risk to single-phase electrical devices connected to it. However, similar to the third type of risk mentioned in Example 1, ordinary factory workers might attempt to use low-power three-phase motors in this alternative socket; in such cases, the three-phase motors will not start and will get damaged due to the lack of a phase or insufficient voltage. Therefore, single-phase sockets and three-phase sockets cannot be used interchangeably; otherwise, it will lead to endless safety hazards.