Home > The Definitive Guide to Selecting the Perfect Terminal Block

Choosing the appropriate terminal block for your application, while appearing straightforward initially, demands a nuanced understanding. Terminal blocks, interchangeably known as screw terminals, terminal connectors, or connection terminals, play a crucial role in establishing secure and reliable connections for multiple wires.

These components offer engineers semi-permanent connectivity solutions across a diverse range of applications. A comprehensive comprehension of the fundamental electrical and mechanical characteristics of prevalent types of junction boxes, coupled with an awareness of safety rating variations, is pivotal for making well-informed decisions.

Terminal blocks serve as the safe bridge between two distinct circuits. Typically drawing power from a larger source carried by a conductor, they find widespread use in industrial environments and power management electronics. Electricians and other installation professionals conveniently employ this fundamental device for seamless installation and electrical integration.

The Definitive Guide to Selecting the Perfect Terminal Block

JINH provides an array of feed-through terminal blocks and isolation strips designed to streamline wire conductive path management with a rear penetration feature accessible through the rear housing.

This article aims to delve deeper into the realm of terminal blocks, shedding light on component disparities, considerations in choosing product types, and adherence to safety regulations.

A thorough understanding of the essential electrical and mechanical characteristics of these commonly used terminal types, alongside an awareness of their diverse safety parameters, is indispensable for making the most fitting choice.

Terminal Types

Screw Terminals

A screw terminal block serves as an electrical connection device comprising a metal block and threaded screws. These screws are tightened to securely clamp the wires, ensuring a reliable electrical connection. This design not only facilitates easy connections but also guarantees a safe electrical coupling.

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Screw Terminals

Spring Lever Connectors

Spring clamp terminal blocks feature a spring mechanism that opens and closes to accommodate wire insertion. Once the wire is placed into the spring clamp mechanism, the spring automatically clamps down, securely fastening the wire. Pressing a button or loosening a screw releases the connection, simplifying the process of plugging and unplugging wires.

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Spring Lever Connectors

Push-In Connectors

Requiring no screws or clamps, push-in terminal blocks enable quick wire insertion. A spring mechanism securely holds the wire in place, and some designs allow for easy release, enhancing the efficiency and convenience of wiring.

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Push-In Connectors

Barrier-Type Terminal Blocks

Barrier-style terminal blocks utilize metal strips to create a barrier, preventing contact between adjacent wires. The wires connect to terminal screws or clips on both sides of the barrier, ensuring a secure electrical connection.

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Barrier-Type Terminal Blocks

DIN Rail Mount Terminal Blocks

Designed for mounting on DIN rails in industrial panels or enclosures, DIN rail terminal blocks can be screw-, spring-, or push-in types. The common denominator is DIN rail mounting, providing a tidy and organized wiring solution.

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DIN Rail Mount Terminal Blocks

Fuse Terminal Blocks

Fuse terminal blocks come with built-in fuse holders, allowing for the connection of fuses to protect the circuit. Wires connect to the terminal blocks, and the fuse is inserted into the designated holder to safeguard the connected circuit.

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Fuse Terminal Blocks

Understand common terminal block specifications

Commonly used terminal block specifications may vary in different fields and industries. The following are some common terminal block specifications used in electrical and mechanical fields

Cable connector specifications

Electrical Specifications

Power socket specifications Cable connector specifications
Make sure the selected power socket complies with international, national or regional standards, such as NEMA, IEC, etc. Carefully verify the voltage requirements of electrical outlets, taking into account the system’s maximum voltage to fully protect against potential damage to connections from voltage surges. Reasonable power socket selection is the basis for the stable operation of the system and avoids unnecessary power compatibility issues. When selecting cable connectors, be sure to choose plugs and sockets that meet standards based on application requirements, such as USB, HDMI, etc. Make sure the selected connector has good signal transmission performance and stable connection. Consider future technology evolution and choose connectors that support high bandwidth and high data transfer rates to meet the possibility of system upgrades.
Terminal block specifications Rated current and conductivity
To accurately determine the appropriate wire gauge for a terminal block, use AWG (American Wire Gauge) or mm² (millimeters squared). Pay attention to the current rating of the terminal block and make sure it is at least 150% of the maximum expected current of the system. This helps prevent overheating issues and ensures system stability under high current loads. When selecting terminal blocks, it is important to consider conductivity, cross-sectional area and corresponding temperature rise. Choose the current rating carefully to prevent overheating and damaging connections. Careful consideration of the conductivity of the wire ensures that current is transmitted efficiently across the connection.
Number of poles Number of poles
According to the specific application requirements, the required number of circuits, that is, the number of poles, is determined. Choose from single-pole to multi-pole terminal blocks to meet the electrical connections your system requires.
Environmental conditions Plug and unplug life
When selecting terminal blocks, the environmental conditions in which they are located must be considered, including the effects of temperature, humidity, and chemicals. Select terminals that meet these conditions to ensure their stability and reliability in harsh environments. To maintain the long-term healthy operation of the system, you need to check the plugging and unplugging life of the connector. Ensure that the selected connectors meet system life expectancy to reduce maintenance frequency and improve system reliability and stability. Carefully consider plugging life, especially in scenarios where frequent connections and disconnections are required.

Mechanical specifications

Connection Type Incoming line direction
Determining the appropriate connection type is an important step in ensuring that terminal blocks are matched to the application. Common connection types include threaded connections, socket connections, and clamped connections. Choosing the appropriate connection method will directly affect the firmness and stability of the connection. The wire entry directions of terminal blocks are usually divided into three common directions: horizontal, vertical and 45°. The horizontal and vertical directions are called 90° and 180° respectively. The choice of wire direction is often dictated by the physical constraints of the overall design, so consideration needs to be given to which direction is more feasible and practical.
Material selection Wire pair housing method
It is critical to understand the materials from which terminal blocks are made to ensure they are sufficiently durable and resistant to corrosion in the application environment. Proper material selection can improve terminal block life and performance. While most junction box connectors have the wires plugged directly into the housing, some variations use pluggable pair housings. This design allows the housing to be plugged directly into the fixed housing on the PCB, simplifying the need to disconnect the main connections without having to disconnect all the individual wires.
application
Module type Protection level
Junction box modules can be constructed as interlocking components or as a single enclosure. Interlocking terminal block modules typically include 2-pole and 3-pole versions, allowing designers to achieve any number of poles required by snapping the modules together. DIN rail terminal blocks typically slide individual units on a metal rail and, once the desired configuration and number of poles are achieved, are protected with compatible end caps. If required, select a terminal block that meets a specific protection class (IP rating) to ensure its resistance to dust and water. The appropriate protection level will ensure that the terminal can operate stably under various environmental conditions and improve the reliability of the system.
One-piece terminal blocks contain all poles in a single housing and are suitable for high-current or high-temperature environments where a single housing is more rugged. These terminals are constructed in a manner that allows the housing to be plugged and unplugged but usually does not allow for multi-piece construction. When selecting terminal blocks, considering these factors will help ensure system reliability, safety and performance. When making decisions, best practice is to refer to relevant technical documentation, standards and specification sheets provided by the manufacturer.

How to Select The Right Terminal Block for Your Project

Now that you understand the specifications, there are a few things to consider when selecting the correct terminal block for your application.

Current requirements

It is important to ensure that the terminal block selected can meet the current needs of the application. Learn more about current fluctuations and peaks in your system so you can choose a terminal block with enough margin to ensure safe operation under the harshest conditions. When considering the current capacity of the terminal block, also be aware of the effects of ambient temperature and wire material on current transfer.

Voltage requirements

When selecting a terminal block, it is important to ensure that its voltage rating matches the voltage requirements of the application. In addition to meeting basic voltage conditions, voltage surges and peak voltages that may occur in the system also need to be considered. Proper voltage tolerance selection will help prevent terminal block damage due to voltage issues.

Wire specifications

The terminal block should accommodate the wires used in the application and maintain a secure connection. When selecting a terminal block, consider the cross-sectional area, material, and diameter of the wires to ensure they will easily plug into the terminal block and provide a low-resistance connection. This helps minimize resistance and heat loss from the wire connections.

Wire specifications

Connection type

The connection type of the terminal block directly affects the ease of installation and maintenance. Choose a connection type that fits your application’s physical space and installation requirements, and ensures that it is compatible with how other system components are connected. This helps simplify system integration and ongoing maintenance.

Protection level

Consider the application’s working environment and select a terminal block that meets the specific protection class (IP rating). High-protection terminal blocks are better able to withstand dust, moisture and chemicals in harsh environments, thereby improving system reliability and stability.

Convenience of installation and maintenance

When selecting a terminal block, consider its ease of installation and maintenance. Choosing terminal blocks that are easy to install and maintain can reduce the difficulty and cost of system maintenance and help increase system availability.

Convenience of installation and maintenance

By fully considering the above factors, you can make a more informed choice of terminal blocks for your specific application, ensuring the efficient operation and reliability of your system.

Conclusion

In conclusion, while terminal blocks may have a seemingly simple design, their diversity in shapes and sizes adds complexity to the selection process. Engineers, however, can navigate this intricacy by thoroughly contemplating and grasping the diverse specifications and selection factors elucidated in this article. By doing so, they can confidently choose the optimal solution for their projects.

JINH stands out by offering an array of terminal blocks, available in various color options and encompassing diverse electrical and mechanical specifications, thus streamlining the selection process.

Whether addressing current requirements, navigating specific environmental challenges, or ensuring steadfast connections, JINH provides holistic solutions. This comprehensive approach ensures that engineers can achieve not only the functionality they need but also the reliability and simplicity vital for project success.

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