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All About Terminal Blocks

All About Terminal Blocks

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Terminal Block is a modular connector engineered for a reliable connection that secures two or more wires together, and manages complex electrical circuits. They are also used for connecting wires to ground or earth connections. Outer bodies of Terminal Blocks are ideally made up of melamine or polyamide material.

Polyamide is a thermoplastic material with excellent electrical and mechanical characteristics. This material is known for high insulation, tracking resistance, and a high flammability score.

Melamine is a thermoset material with dielectric properties. It has a high level of resistance to hot, cold and damp environment; retaining its electrical and mechanical stability. Also, it has excellent insulation properties and high resistance on flashover.

Ceramic is a sturdy material that can be used in extremely high temperatures. Ceramic blocks are preferred in industrial plants with excessive dust deposits and abnormally eroding environments.

Terminal Blocks majorly uses a copper alloy to ensure very low contact resistance. The wires are securely connected to current bars with the help of clamps; these clamps can be screw clamps, spring clamps, nut & bolt or studs. There are different types of lugs or ferrules available for connecting the wires to Terminal Blocks for e.g., pin-type, tubular, hook type, fork type and ring type lugs depending on the area of application, current & voltage ratings. There are a variety of Terminal Blocks used in the electrical industry as per application and circuit requirements like Standard Feed through Terminals, Multiple connection Terminals, Double Level & Triple Level Terminal Blocks, Micro Terminal Blocks, and Sensor Terminal Blocks, CT connection Terminals, Fuse Terminals, Bus bar Terminals and most important Grounding / Earth Terminal Blocks. These Terminal Blocks are mostly DIN Rail and can be mounted on standard DIN32 & DIN35 rails which are widely used in panel boards for mounting other electrical equipment like MCB’s and MCCB’s etc.

Spring-loaded Terminal Blocks are preferred for connections that adhere to safety requirements of the Electric Supply Industry standards (ESI).

CTS Assembly With Reflection



Terminal Block design and development is mainly driven by standards to ensure quality performance, safety and universal acceptance of products. Standards from UL and IEC are utilized for design and development, while third party approvals like UL, CSA, VDE, CE, ATEX etc. from reputed organizations ensure that manufacturers adhere to the standards. 



Types of connection Methods:

Screw Clamp connection:

Screw Clamp Connection is the most popular method of wire termination. It offers distinct advantages over the other wire termination methods such as (i) Suitable for all types of wires, (ii) Wires can be connected without any special preparations (iii) Simple connection and disconnection of wires with the aid of an ordinary screw driver. 

CTS4UN         Screw2

The steel clamping screw produces high contact force while the steel clamping yoke transmits this force by pressing the conductor against the current bar, which is made up of electrolytic copper. When the clamping screw is tightened, the clamping yoke gets pulled upwards, pressing the wire against the current bar. A flat clamping area ensures safe grip of wires of smaller cross sections.

Screw3      Screw4

Spring Clamp connections:  

Screw-less Spring Clamp connection is as versatile as Screw Clamp connection.  In this type of connection, the wire is held against the electrolytic copper current bar directly by a pre-stressed spring clamp. The spring is operated by using a screwdriver to provide access to the wire through the opening in the spring clamp. The inserted wire gets clamped on to the current bar on the removal of the screwdriver. The high-quality stainless steel clamp ensures a good connection of the wire with minimal contact resistance. The features of Spring Clamp connection are (i) Easy operation and time-saving connection method, (ii) Vibration proof connections (iii) Fail proof safe and maintenance-free connections.


Cable Lug and Bus bar Connection:     

This method of wire termination is preferred for connections that are subject to very severe vibrations. The wire is crimped to ring or fork type lug and is screwed on to the flat current bar in the Terminal Block. This type of connection is also preferred for wires of larger cross-section; the conductor is fitted with a ring lug and bolted on to a flat current bar.


Tab Connection Method:

Tab connections are preferred in applications where the connected wire needs to be frequently connected and disconnected. Tab sleeves with the crimped wires are pushed on to the Terminal Block. These are simple connections and allow connection and disconnection of wires in a circuit with ease.


Solder Type Connections: 


Solder connections are suitable for wires up to 2.5 sqmm. In this type of connection, the wire is soldered to a solder lug. These are firm and permanent type connections and cannot be easily removed.

Push-in Type Connections:

Push-in Type connection is a next-generation connection method and offers tool-free direct push-in type connections. Solid conductors can be directly used whereas stranded wires are lugged and pressed inside the clamp. The clamp is automatically opened and the wire gets locked inside the Terminal. Some of the features of this connection method are (i) Time-saving and fool-proof connections (ii) Convenient wire insertion without using any tool (iii) The wires can be easily released when required.  

Cppushin Action     

Plug and Socket Connection:

Pluggable connection type Male – Female Terminal Blocks are an excellent solution for creating a wire harness. These can be either Din Rail mounting or Free Floating connections and find application is machine building wherein two separate units are brought together and electrically interconnected.