Cable Lugs – Crimping Applications & Standards

Published 29 Aug 2018

Cable Lugs – Crimping Applications & Standards

Cable Lugs – Crimping Applications & Standards

  • uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager
    

Thorne & Derrick International, based in the UK, are leading suppliers of cable crimp lugs and associated crimping tools for Low, Medium & High Voltage Cables and Power Systems – this series of articles by Klauke discusses the theory and practise of installing compression type cable lugs and connectors.

Klauke cable lugs and crimping tools are used by Jointers, Linesmen, Panel Builders and Electrical Engineers to install underground cables and overhead line conductors on power, transmission and distribution networks including LV MV & HV systems, 11kV-33kV.

➡ Download 2018 Klauke Cable Lugs catalogue and see the complete range of tools for cutting and crimping cables.

In this Article we cover the following:

  • Compression cable lugs according to DIN 46235 for crimping solid, stranded, fine stranded and finest stranded copper conductors
  • Copper tube cable lugs “standard design” made from electrolytic copper (EN 13600)
  • Compression cable lugs DIN 46235 terminals not for solid conductors
  • Selection of the correct lug very much depends on the cable type
  • International Standard IEC 1238 Part 1 – electrical and mechanical properties of cable lugs

Although cable connections are relatively low cost in comparison to price-per-metre of cable and often a project afterthought the importance of specifying and installing the correct type of lug is critical to safe and reliable performance of LV MV HV Power Systems – a poor cable connection can result in an increased joint resistance and even in fire. Worse still, fatality.

Incorrect Tools

Incorrect tools and cable crimps cause increased temperatures and fire.

In this blog T&D will show you the correct cable crimping procedure. There are hundreds of different versions of cable lugs available.

For the electrical engineer and cable jointer it is very difficult to choose from this broad range the correct lug for each specific application.

The following article gives an overview of the different types of lugs for copper conductors and details the facts which will guarantee a safe and permanent electrical connection.

In principle we differentiate between 3 types of cable lugs:

Compression cable lugs according to DIN 46235

DIN Standard 46235 defines the application, dimensions and marking of cable lugs – this standard allows use of these lugs for compression of solid, stranded, fine stranded and finest stranded copper conductors and cables.

DIN Compression Cable Lugs

3 types of lugs: DIN cable lugs, standard tubular cable lugs and sheet metal terminals (from left to right)

Markings on the product provide the installer with information relating to the origin and application of the DIN 46235 cable lugs, which also applies for standard tubular cable lugs.

DIN Compression Cable Lugs

DIN crimp cable lugs show the required number of crimps stipulated by the manufacturer: Marking “KL 22 12 – 150” 

  • KL: indicates manufacturer (in this case Klauke)
  • 22: Die set code (only for compression lugs DIN 46235)
  • 12: Metric bolt size for connecting bolt: size M12 (12mm hole diameter)
  • 150: Cross section of conductor in sqmm

In addition, these lugs indicate the number of required crimps. For installing, the DIN standard recommends crimping dies according to DIN 48083, Part 1, 3 and 4 for solid, stranded and fine stranded conductors.

For braided ropes the standard refers to the information of the manufacturer.

Klauke generally recommends the use of hexagon crimping dies according to DIN 48083, Part 4 for installing of compression lugs DIN 46235 – the range of cable conductor cross sections is from 6sqmm up to 1000sqmm, bolt sizes range from 5mm up to 20mm.

Electrolytic copper according to EN 13600 is mandatory.

For corrosion protection the compression cable lugs – also standard tubular cable lugs and terminals – are tin plated to protect against oxidisation.

Copper tube cable lugs “standard design”

Apart from DIN cable lugs, many manufacturers also offer standard tubular cable lugs, also made from electrolytic copper according to EN 13600. As far as sizes are concerned, standard tubular lugs are mostly shorter than DIN lugs and also differ in tube dimensions.

  • DIN EN 13600 Copper & Copper Alloys – Seamless Copper Tubes For Electrical Purposes; German version EN 13600:2013

DIN compression cable lugs are longer than standard tubular cable lugs

However, since these lugs are also subject to test standard IEC 1238 Part 1 the durability of electrical and mechanical connection is not affected.

All lugs – irrespective of type – can only be crimped properly when a suitable cable crimping tool is used. Incorrect tools or an unprofessional crimp can result in increased joint resistance, increased temperatures and even fire.

Standard tubular cable lugs

Standard tubular cable lugs (left) have different tube dimensions to DIN crimp cable lugs (right)

To eliminate this risk Klauke recommends the crimping of their lugs with their tools – this is a matched crimping systems avoid a mixture of brands which are potentially incompatible.

Sheet metal terminals according to DIN 46234

Solderless Terminals

Also for the sheet metal terminals certain DIN standards apply regarding application, dimensions and marking.

Other than compression cable lugs DIN 46235 terminals are designed only for crimping of stranded, fine and very fine stranded conductors – not for solid conductors.

Incorrect Crimping

Incorrect Crimping

Incorrect Crimping

Incorrect Crimping

Correct Crimping

Correct Crimping

Incorrect and correct crimps in comparison: An incorrect crimp (crimping,middle: low force crimping, and usage of incorrect crimping tools can result in an increase in joint resistance and may jeopardise the installation)

Which cable lug suits which application?

Cross section ranges from 0.5sqmm up to 240sqmm, bolt sizes from 2mm to 16mm.

Among others terminals they can be found in electrical control cabinets and vehicles of public transportation services, such as rail carriages and rolling stock.

Sheet metal terminals are also made from electrolytic copper according to EN 13600. But there is a difference in the basic material – compression standard tubular lugs are produced from copper tubes while solderless terminals are made from copper sheets.

Terminals show a soldered seam as the DIN standard prescribes a closed tube.

The DIN standard does not specify crimping tools – Klauke recommends their self-designed indent crimping tools.

Useful Information

The selection of the correct cable lug very much depends on the cable type. For cables according to DIN 57295 the following lugs can be used:

  • Cables Class 1, 2, 5 and 6: Compression lugs DIN 46235
  • Cables Class 2: Standard tubular lugs
  • Cables Class 2, 5 and 6: Terminals

In practice it can happen that flexible class 5 and 6 cable conductors do not fit into the appropriate cable lug. For such cases, Klauke recommends the so called F-cable lugs which have a larger inner diameter and feature a flared entry. Indent crimping is recommended.

For installing the DIN lugs, crimping tools with die codes according to DIN 48083 Part 4 have to be used.

Electrical & mechanical properties

The International Standard IEC 1238 Part 1 applies to electrical and mechanical properties of cable lugs. The requirements for a permanent and safe electrical connection for the intended application are detailed in this standard.

Both a mechanical pull-out test and an electrical durability test are defined.

A test cycle simulates the application in practice: the connection is being heated 1000 times up to 120°C to imitate the morning voltage peak in-rush in the public power supply system.

Also high current tests are being carried out on the cable lugs at temperatures of 250°C.

The responsibility of adherence to these safety rules lies with every manufacturer of cable lugs. For this reason the manufacturers specify the appropriate cable type to be used with their lugs. Apart from normative standards, renowned manufacturers stipulate additional quality requirements.

F-Cable lugs

F-Cable lugs with flared entry represent an option when cables of class 5 and 6 will not fit into normal cable lugs.

Klauke cable lugs are subject to an “annealing” process to condition the material from tension and hardness and to reduce the risk of fracture. F-Cable lugs with flared entry represent an option when cables of class 5 and 6 will not fit into normal lugs.

This process increases the durability and provides greater protection for the lug against vibration. This is another reason why Klauke recommend use of high-quality cable lugs from well known manufacturers.

Klauke Cable Lugs

The longer tube of Klauke cable lugs (above) guarantees a high quality connection.

The quality of lugs can often be recognised by visual characteristics: burr free cable lugs with flat palm and a cleanly machined end are signs of a high quality electrical connector.

High Quality Klauke Cable Lugs

High Quality Klauke Cable Lugs

Further Reading

Review other Blogs in this series of articles about Cable Lugs, Crimping Cables & Tools:

Copper Cable Lugs For Special Applications

Indent Crimping Of Cables – Benefits & Limitations

Cable Lugs & Crimps – Hexagonal v Indent Methods of Crimping

Cable Lugs & Crimping Using The Hexagonal Crimp Method

DIN Standard – Crimping & Compressing Aluminium Cable Lugs & Connectors

Copper & Aluminium – Crimping CU-AL Cables

Electrically Driven Crimping Tools For High Volume Applications

 

LV MV HV Cable Accessories & Substation Electrical Equipment

Thorne & Derrick are Specialist Distributors of leading manufacturers of Cable Accessories, Jointing & Installation Equipment.

LV MV HV cable accessories used to joint, terminate, connect, cleat and gland power cables to air and gas insulated substations, transformers, switchgear and overhead line networks.

Hover over our Interactive Electricity Grid to learn more about our product ranges.

LV 600/1000V ◊ MV 11kV 33kV ◊ HV 66kV 132kV 

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Further Reading