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Most Comprehensive Terminal Block Considerations
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Most Comprehensive Terminal Block Considerations

Views: 180     Author: Site Editor     Publish Time: 2020-10-06      Origin: Site

With the development of the electronic industry, the use of terminal blocks is more and more widely, and the types are more and more. However, when connecting the connection terminals, care should be taken to prevent the terminals from malfunctioning or not being used. So, what should be paid attention to when connecting terminal blocks?

In general, there are two main factors to consider.

Electrical Considerations

Besides the overall system voltage and current requirements, there are other factors to consider.

1. Current Rating

The current rating is often the most important parameter to consider in terminal block designs. The current rating is based on the conductivity of the terminals, the cross-sectional area, and the corresponding heat rise. Operating at too high of current can cause overheating and damage of the terminal block, leading to major safety concerns. It is best practice to use a terminal block that is rated for at least 150% of the max current that is expected in the system.

2. Voltage Rating

The voltage rating is in part determined by the dielectric strength and pitch of the terminal block housing. The maximum system voltage of the application must be less than the voltage rating. Any voltage surges in the system should also be evaluated when selecting the terminal block.

3. Wire Size/Type

The minimum and maximum wire size that the terminal block can accept would be a function of the voltage/current rating. In addition to making sure, the wires used will physically fit into the terminal block, the type of wire should also be considered. Stranded or multi-core wire is typically used for screw terminals, and single-core is typically used for push-in style terminal blocks. In North America, wire size is specified in units of American wire gauge (AWG).

4. Only two conductors of the same type and specification can be connected to the same terminal. 

electrical connector blocks


5. For the terminals that are easy to be loose or in poor contact, the wire connector must be fixed on the terminal with a question mark, so as to increase the contact area and prevent looseness.            

6. When the wire joint or nose of the terminal is connected with each other, it is strictly forbidden to install a noncopper gasket or poor conductivity gasket in the middle.            

7. The contact surface shall be smooth and free of oxidation when connecting the terminal wire joint. When connecting the connection nose or copper bar, the contact surface should be coated with conductive paste after cleaning, and then tightened.            

8.When the terminal is connected with a temporary wire, the connector of a single conductor shall be folded in half once, and then the connector shall be connected to the empty opening, and the single-core hard wire shall be connected to the empty opening in the form of the question mark.           

9. For motors of 30kW and above, it is not allowed to jumper the gaskets with poor conductivity between the motor outgoing line and the cable connecting the motor, such as galvanized nuts, flat pads, and spring pads.            

10. When using insulating tape to wrap the cable connected with the terminal or other equipment to be insulated, the insulation layer should be wound from one end to the other according to the pressure ratio of 1 / 2, and it needs to be wound back and forth.


Mechanical Considerations

1. When tightening the wiring, the wiring terminal should be applied with moderate force to prevent the terminal from being damaged by excessive force. The loose terminal block should be replaced in time. It is strictly forbidden to continue working under the condition of loosening or falling.            

2. When the terminal is fastened or loosened with a screwdriver, the screwdriver must be forced to tighten the screw, and then the screw can be tightened or loosened to prevent the screwdriver from sliding with the screw, thus causing damage to the screw and making it difficult to disassemble and assemble, especially the commonly used air switch in the hanging box.            

3. If it is difficult to remove the bolts and nuts, do not act rashly to prevent the screw deformation of the terminal, which is more difficult to remove. Appropriate knocking should be given or screw loosening agent and dilute hydrochloric acid should be added before disassembly.           

4. Do not use a vise to tighten or loosen the bolts and nuts connecting the terminals to prevent damage. Adjust the opening when using a spanner wrench to prevent bolt and nut damage and deformation, which will make disassembly and assembly difficult.


Other Design Considerations

In order to make assembly or maintenance easier for the user, housing color or special markings can be modified to help differentiate various terminal block connections. This is especially useful for more complex systems that utilize multiple wiring and circuits housed in a centralized location.

The operating temperature of the end system also needs to be considered to know whether a high temperature rated terminal block would be needed.


As China famous terminal block manufacturers, Sun provides professional electrical terminal block information and high-quality electrical terminal blocks. If you have any needs, please contact us.

Sun Electric Co., Ltd
Founded in 2011, Sun Electric Co., Ltd specializes in the production of terminal blocks and industrial electrical connection products.

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