IEC Standard 61914 : Cable Cleats & Short-Circuit Calculations For Electrical Engineers

By Chris Dodds on 21st January, 2015

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IEC 61914:2009 specifies requirements and tests for cable cleats and intermediate restraints used for securing cable in electrical installations.

Cable cleats provide resistance to electromechanical forces where declared. This standard includes cable cleats that rely on a mounting surface specified by the manufacturer for axial and/or lateral retention of cables.

Electrical design engineers and specifiers specify power cables from which the maximum anticipated short circuit load can be calculated.

This data enables the calculation of the force between the cable conductors in a short-circuit situation - cable cleats installed to cable containment (whether cable tray, ladder or basket) are in turn specified at the correct spacing to contain potential short-circuit forces generated by the low/high voltage power cable system.

IEC 61914:2009 provides a method for cable cleats to be short circuit tested so that results for IEC Cable Cleats different types of cleats can be compared.

The cable cleat manufacturer should determine the fault level at which they wish to test their cable cleats.

However, the cable must be unarmoured single core 600V/1000V stranded copper conductor cable and the testing assembly must be in accordance with the requirements of the standard.

Video : Short Circuit 118kA Peak. Ellis Patents Emperor Trefoil Cleats subjected to short circuit test retaining 3 x single core cables to slotted rung cable tray. 

For a range of cable cleats to be classified under the IEC Standard at a particular fault level, it must undergo one or two short circuit tests depending on classification and afterwards :

1. There shall be no failure that will affect the intended function of holding the cable in place.
 

2. The cable cleats and intermediate restraints, if used, shall be intact with no missing parts (minor deformation is acceptable).
 

3. There shall be no cuts or damage visible to the outer sheath of the cable caused by the cleats or intermediate restraints.

4. There shall be no failure that will affect the intended function of holding the cable in place.

5. The cable cleats and intermediate restraints, if used, shall be intact with no missing parts (minor deformation is acceptable).

6. There shall be no cuts or damage visible to the outer sheath of the cable caused by the cleats or intermediate restraints.

 

IEC 61914:2009 also provides formulae to enable the theoretical forces between conductors in the event of a short circuit to be calculated.

Where:

•             F = maximum force on the cable conductor in trefoil formation for a three phase short-circuit (N/m)

•             Ip² = the peak short-circuit current (kA)

•             S = the cable diameter (m)

 

Ellis Patents Cable Cleats

 

Vital Short Circuit Protection with Ellis Patents Cable Cleats
 

Ellis Patents cable cleats provide safety critical support to vital cable circuits.

Cable cleats must withstand peak short circuit forces generated by the actual cable installation - Ellis Patents 3rd party certified cable cleats provide peace of mind containment of low and high voltage cables. 

Ellis Patents are a leading voice in the campaign to have cable cleats reclassified as short-circuit protection devices. A move that would mean cable cleats would be placed on a parallel with fuses and circuit breakers.

"This reclassification makes absolute sense. In the event of a cable fault, the forces between cables reach their peak in the first quarter cycle, which is the point that cable cleats earn their crust. In contrast, circuit breakers typically interrupt the fault after 3 or even 5 cycles by which time, if the cable cleats are underspecified, the cables will no longer be secure, but will be putting vital electrical installations and lives at unnecessary risk," says Paul Nolan UK Sales Manager, EP.

T&D thank Isabelle Noury & Andy Booth (Ellis Patents) for supporting and contributing to our Blog. 

 

Video : Comparing Electrical Performance Of Stainless Steel Cable Cleats v Stainless Steel Cable Ties In Short-Circuit Test Situation.

 

YouTube Video Playlist : Ellis Patents Cable Cleats, Cable Clamps & Hooks

 

Video : Cable Ties on Cable Ladder - The Importance of Cable Cleats on Multi-Core Cables 

  • Further Ellis Patents reading

Ellis Patents Cable Guide Clamp - Video

Cable Cleats - The Ellis Patents Black Book Guide To Cable Cleats 

Cable Cleats From Ellis Patents - The Innovation Game 

Ellis Patents Pegasus Cable Hangers

 

Invitation

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Discussion subjects include cable installations, cable jointing, electrical substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.

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Category:  Cable Cleats & Cable Ties

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