Total equipotential bonding (MEB): total equipotential bonding in the whole building, it can reduce the degree of indirect contact within the building electric shock contact voltage and the potential difference between different metal parts, and eliminate the building from outside the introduction of electrical wiring and all kinds of metal piping hazardous fault voltage hazards. It should be through the incoming power distribution box near the grounding busbar (total equipotential connection terminal board) will be the following conductive part of the interconnection:
-- incoming power distribution box PE (PEN) busbar;
-- utilities of the metal piping, such as water, sewer, heat, and gas piping;
--Metallic structure of the building;
--If an artificial ground is provided, it also includes its grounding electrode lead.
Residential buildings to do the total equipotential bonding, can prevent the TN system power lines in the PE and PEN wire conduction to introduce fault voltage caused by electric shock accidents, at the same time, can reduce the potential difference, arc, electric sparks occurring chances of avoiding grounding faults caused by electrical fire accidents and personal electric shock accidents; but also necessary for lightning safety. Therefore, in the building of each power inlet, there is generally a total equipotential connection terminal board, by the total equipotential connection terminal board and into the building of the metal pipeline and metal structure components for connection.
Auxiliary equipotential bonding (SEB): in the conductive part of the direct connection with wires, so that their potentials are equal or similar, called auxiliary equipotential bonding.
Local equipotential bonding (LEB): in a local place within the scope of the conductive part of the connection, called the local equipotential bonding. It can be connected to each other through the local equipotential bonding terminal board:
-PE bus or PE trunk;
-Utility metal piping;
--metal structure of the building;
--metal structure of the building;
--metal structure of the building;
--metal structure of the building. -Building metal structures;
Bathrooms are classified by the International Electrotechnical Standard as special places with high risk of electric shock. In our country bathroom electric shock accidents have occurred repeatedly, resulting in personal injury, this is because people in the shower all over the body wet, the human body impedance is greatly reduced, along the metal piping conduction to the smaller voltage can cause electric shock casualties, so in the bathroom for the local equipotential connection can make the bathroom is at the same potential, to prevent the emergence of dangerous contact voltage, and effectively ensure personal safety.
In the residential design and construction, we found that the total equipotential linkage can be seriously implemented, but the local equipotential linkage is not enough attention, the construction of how to make local equipotential linkage there are still some questions. Below, I am in the construction drawings, bathroom local equipotential bonding practices are detailed below:
In the bathroom local equipotential bonding, should be the metal water supply and drainage pipe, metal bathtubs, metal heating pipes and ground reinforcement network through the equipotential bonding line in the local equipotential bonding terminal plate together, when the wall is a concrete wall, the wall reinforcement network is also desirable with the equipotential bonding line connected; Metal floor drains, handrails, towel racks, soap boxes and other isolated objects can not be connected. Local equipotential interconnection terminal plate should be bolted, set in a convenient location for testing, in order to dismantle for regular testing; equipotential interconnection line using BVR-l X 4 mm2 wire in the ground and the wall through the plastic pipe laying, equipotential interconnection line and the terminal plate should be made of copper material, because of its conductivity and strength are better.
Additionally, it should be noted that the bathroom if there is no PE line, the bathroom of the local equipotential coupling shall not be connected to the PE line outside the bathroom, because the PE line may be elsewhere due to faults and charged potential, but can be introduced into the potential elsewhere; if there is a PE line in the bathroom, then the bathroom of the local equipotential coupling must be connected to the PE line. Because now there is almost no metal supply and drain pipes, metal bath tubs and other metal components in the residential bathroom, and no heating pipes in the Guangzhou area, so only in the equipotential bonding terminal board reserved for spare terminals for residential decoration when the choice of metal sanitary ware to do the equipotential bonding.
In the following diagram of the local equipotential connection in the bathroom, including the bathroom spare socket, electric water heater socket, gas water heater socket and sanitary ware socket PE wire, mirror lamp PE wire, the bathtub of the reserved junction box and the building reinforcing network connected to the floor or wall embedded parts of the floor or wall were connected to the local equipotential interconnecting terminal board (LEB).
Equipotential connection after the installation of conductivity test, test power supply can be used for no-load voltage of 4 ~ 24V DC or AC power supply, test current should not be less than 0.2A, when the measured equipotential connection terminal plate and equipotential connection within the range of metal piping and other metal bodies between the end of the resistance does not exceed 3 ohms, equipotential connection can be considered to be effective. If the pipeline connection is found to have poor conductivity, it should be jumpered, and the conductivity test should be made periodically after it is put into use