Terminal blocks are insulated, modular blocks that connect two or more wires. Terminal blocks are generally used for securing and/or terminating any wires. In most of the basic forms, they are made up of multiple or separate terminals grouped in a long strip.

Terminals are used to connect wiring to the ground or to connect electrical switches and other outlets to the main supply in the case of any electrical power source. Terminal bodies are usually made of a copper alloy that has the same coefficient of expansion as the wire that will be used.

This eliminates the chances of not just loosening due to varying expansion rates, but also the corrosion induced by electrolytic activity between two dissimilar metals. They can also be used for securing the connections on applications that are subjected to high vibrations.

Why use terminal blocks?

Usually, terminal blocks are considered to be a much better and cleaner solution to connect wires, as they can offer more flexibility. As an example, when you use any terminal blocks, then wiring modifications will be quite easy, as wires can easily be added or removed. Terminal block wiring will offer a neat and orderly look, and allow you to quickly identify the right wires while making any modification or troubleshooting.

Terminal block characteristics

You can classify terminal blocks based on characteristics e.g. device type, structure, and termination options. There are several methods employed for connecting the wires inside any terminal block as mentioned below.

• Screw-in terminal block

  This is perhaps the most common method. As the name suggests, it will have a screw system for fastening the wire terminals. You will however need to be careful while tightening the screws as too much tightening could damage the wires. The connection could also be lost due to that.

  
  

• Barrier terminal block

  This is also the block having the screw system, but with an additional lid to give more protection to the terminal. You will need to do precise cutting of wires while using these blocks for the clamps to be properly positioned.

  
  

• Pluggable terminal block

  A pluggable terminal block is the latest addition of Sun Electric Co. of China, which is one of the leading manufacturers of terminal blocks. You can check out their website for complete specifications. It has a plug outlet for allowing connection to any socket. Here the wire will be inserted and then clamped with a screw. All the connections to the wire can be made through a plug/socket configuration. This type is particularly useful when you have to disconnect the lines quickly.

  
  

• Spring-cage terminal block or spring-loaded connection

  
  

  The spring-loaded terminal block is another common type. As the name suggests, it will have a spring coil to exert additional pressure. You will need to first need to use the ferrule ring before inserting and fastening the wires with the screw. It helps in securing the connection.

  
  

• Push-in or push-fit terminal block

  This type is gaining more popularity these days. It is quite similar to spring-loaded types, but the difference here is the direction of pressure on both sides. The push-out type is more ideal for quick releasing of connection, while the push-in works in the opposite direction for better fastening.
  

  
  

• IDC terminal block

  It stands for Insulation Displacement Connector terminal block. It gives the advantage of using wires without having to cut them to expose the terminals. It has inbuilt blades as the slicing provision to do the task while the wire is being inserted. It works well on all types of wires.
  

  
  

• Tab connector terminal block

  In this type, the blocks are connected to other connectors in the form of tabs. It has the provision for connecting to other connectors on one side, while the other side will have normal screw and clamp slots for wires. You could opt for crimp type or soldering type based on your custom requirements.
  

Terminal Block Types

You will find several varieties of terminal blocks that are used in a design. The following are a few most commonly available types:

• PCB mount

  This type allows for the housing of terminals onto the PCBs. They can be used as a standalone or as a multi-level mounting module, depending on the application. The terminals are connected to the PCBs with the help of soldering.
  

  
  

• Feed-through

  This allows for connection 2 writes on the opposite sides. One side will be considered as the input side and the other one will be for the output. Very much like the PCB mount, these ones can also have single or multilevel slots.

  
  

• Barrier Strips

  This is a screw-down type which is ideal for connections where the vibrations are high. The barrier rings will secure the connectors even if the wires experience high vibrations. You will need to push the barrier around the wire before inserting it into the terminal.

  
  

• Ground terminal block

  At a very first glance, any ground terminal block may appear like any typical screw-in terminal block. The only difference here is that it is used for grounding wires instead of securing the connection to other wires.

  
  

• Fuse terminal block

  This type gives additional protection to the connections with the fuse system in between the line-in and line-out. If there is a sudden spike in the current supply, the fuse will protect the appliance by terminating the connection. It helps in protecting the appliance in cases of spikes.

  
  

  It does not require an additional protection mechanism externally. The fuse status is indicated by the LED lights, which allow for quick troubleshooting. Technicians can quickly identify the area when the fuse blows off.

  
  

• Thermocouple terminal block

  This is designed for accepting thermocouple lead wire connections. Typically, they cannot be attached to normal terminal blocks, because they cause the unwanted junction while connecting with other types of wires. It lowers the efficiency of the connection, but this type of block is designed to overcome that glitch.

While there are numerous aspects to consider when constructing an overall system, suitable terminal blocks are the most efficient way to link complicated electrical systems.