Hope to adopt
Question 2: What is the equipotential in the building? You're absolutely right! The so-called equipotential means equipotential with the earth, and there will be an equipotential box in each distribution room, which is directly connected to the neutral grounding system of your distribution transformer! The equipment in the computer room should be grounded, one is anti-static interference, and the other is lightning protection!
Question 3: What does a power plant need to connect to the secondary equipotential grounding network for? What needs to be connected to the main grounding grid? 5 points Basically, all metal cabinets must be grounded. If grounded, it is connected to the main grounding network!
The so-called secondary equipotential network is also the equipotential equalization network in the secondary machine room. The balance network is also led from the outdoor main grounding network! General multi-point access to the main grounding network!
Outdoor primary equipment is also grounded, that is, it is directly connected to the main grounding network!
Question 4: I wonder if there is total equipotential when the old house is rebuilt and used. What about electrical grounding? There was no equipotential line at home before. The so-called equipotential line is actually the connecting line between the lightning protection network and the grounding line, which has no practical significance. If there is no grounding wire, you can use a 2-meter-long steel pipe or angle steel to drive into the ground and connect a wire as the grounding wire.
Question 5: How does equipotential technology prevent lightning? Equipotential is used to distribute the high voltage generated by lightning strike to all lines, so that their potentials will rise at the same time. Prevent breakdown or melting caused by excessive voltage difference between them.
Question 6: How big should the flat iron be for the local equipotential box in the bathroom? -25*4 galvanized flat steel.
Question 7: What are the technical requirements for equipotential terminal boxes used in clean laboratories (300,000 class)? Equipotential bonding is one of the main measures to prevent electric shock accidents in low-voltage AC distribution system. Total equipotential connection is to connect the protective trunk line, distribution trunk line or total grounding terminal, public pipelines (such as water pipes) and similar metal parts in buildings with the available metal components of buildings, central heating pipelines and air conditioning systems. Similar components and pipes entering the building are connected near the entrance of the building to balance the potential, reduce the contact voltage and eliminate the dangerous voltage introduced into the building by power lines. Its purpose is to make the potential between the exposed conductive part and the external conductive part that people can touch at the same time roughly equal, that is, to reduce the contact voltage below a safe value, so as to prevent these objects from hitting back the insulation and cable core in the equipment due to the high voltage induced by lightning or the high potential conduction of lightning to the earth on the grounding device. For more details, please move to Dongguan and official website.
Construction technology requirements: equipotential shall not be moved or damaged. If sealing is required, the inspection port must be reserved.
Question 8: Is the equipotential bonding of toilets in high-rise buildings partial or complete? Anything will do. Provide detailed analysis, hoping to help.
Standard drawing for equipotential bonding installation Author: Xu Hua
Combined with the revision of the national standard drawing of Equipotential Bonding Installation (97SD567), some new understandings of equipotential bonding are discussed, and the problems in the implementation process are briefly discussed.
Equipotential bonding; Ground fault; Lightning protection; Equipotential surge protector
At present, many newly revised codes and standards in China are gradually in line with the international electrotechnical standards (IEC standards). Equipotential bonding is an effective safety measure in electrical design, which has long been adopted by many countries in the world. China has also made great progress in understanding the role of equipotential bonding. Equipotential Connection Installation compiled by 1997 puts forward some basic methods. Since the trial implementation, many practical problems have been encountered in the construction process, especially the rapid development of information technology, which puts forward higher requirements for lightning protection, grounding and equipotential. Therefore, referring to the new international and domestic standards and practices, we revised the original standard drawing 97SD567.
1 classification of equipotential bonding
When compiling 97SD567, the author made an analysis and comparison between equipotential bonding and equipotential bonding, and decided to adopt the name of equipotential bonding in this drawing set. However, in practical work, these two words are often confused. I want to emphasize that any standard or specification must have a standardized name if it is to be realized correctly. For detailed analysis, please refer to the compilation of Equipotential Bonding Installation Standard Drawing (page 233 of Modern Building Electrical Design Technology Compilation). In the general description, equipotential bonding is divided into three levels, namely, total equipotential bonding, auxiliary equipotential bonding and local equipotential bonding.
The total equipotential bonding acts on the whole building, and the equipotential bonding terminal board is used to connect or connect metal pipes, metal structural members, etc. In and out of the building. Auxiliary equipotential bonding is to connect the conductive parts directly with wires to make their potentials equal or close. Generally, it is used as an auxiliary equipotential connection when the grounding fault protection of a certain part of the electrical device cannot meet the time requirement for cutting off the circuit.
Local equipotential bonding is to connect all conductive parts in a local place through a local equipotential bonding terminal board. Generally, in bathrooms, swimming pools, hospital operating rooms, agriculture and animal husbandry and other particularly dangerous places, the risk of electric shock accidents is high, and the contact voltage is required to be low, or in order to meet the anti-interference requirements of information systems, local equipotential bonding generally has terminal boards or rings. Simply put, local equipotential bonding can be regarded as the total equipotential bonding in this local range. This difference can be understood by drawing on page 6 of the atlas.
2 The effectiveness of equipotential bonding
In the test of the continuity of equipotential bonding in the atlas, the resistance requirement of 3 Ω is put forward, mainly referring to the German standard. Equipotential bonding is only an additional protective measure to prevent indirect contact electric shock. Resistance requirements mainly put forward quantitative standards for the continuity of equipotential connection, which is easy to implement in practical work. Therefore, before the electrical equipment is put into operation, the pipe clamps, terminal boards, connecting wires, related joints and color codes on the whole path of equipotential bonding should be inspected, and the resistance between the equipotential bonding terminal board and the end of the metal pipe within the equipotential bonding range should be measured. Some people worry that there is no good remedy when the measured resistance does not meet the requirements. In fact, the measured resistance is mainly contact resistance. If the connection is reliable or some jumpers are added, it should not be difficult to achieve less than 3ω. In the continuity test, DC or AC power supply with no-load voltage of 4 ~ 24V can be used, and the test current is not less than 0.2A It is better to use the test current of 5A, and the measured value is inaccurate if the current is too small. At present, there are specialized manufacturers at home and abroad to produce testers for detecting equipotential bonding, which is convenient for testing.
The effectiveness of auxiliary equipotential bonding and local equipotential bonding to electric shock can be verified by the following formula:
R≤U 1/Ia
Among them:
R refers to the resistance (ω) between the exposed conductive part that can be touched at the same time and the external conductive part of the device;
Ia-action current of protective appliances for cutting off the fault circuit for no more than 5s (a);
U 1-Allow ... >>
Question 9: I want to ask if equipotential has not been done at home before, but can it be replaced by iron tapping? The so-called equipotential means that all the appliances in your bathroom and kitchen are grounded on a bus (in fact, they are twisted together).
Question 10: What is local equipotential bonding? Why do residential bathrooms need local equipotential bonding? The local equipotential bonding in the bathroom is to connect the metal pipes and metal components in the bathroom to the equipotential bonding terminal board through equipotential bonding wires, so that the potential in the bathroom is at the same potential, even if the potential is higher than the ground potential, there will be no potential difference within this range, thus avoiding the occurrence of electric shock accidents. When bathing, the human skin is completely soaked, and the human impedance is high (N 1- drop). Small voltage conducted along metal pipes and metal parts can lead to electric shock casualties. This kind of electrical accident cannot be prevented by installing leakage protectors, isolation transformers and other protective appliances, because the voltage that causes casualties is conducted along non-electric metal pipes and metal components, and the only preventive measure is to make local equipotential connection here. After doing this, no matter where abnormal voltage is induced, due to the action of equipotential bonding, the potential of all conductive parts in the site rises to the same potential level at the same time, so that there will be no potential difference and no electric shock accident.