Belden Essential Cable Facts: Electrical Current

Cross section of a cable conductor

The cross section of a cable conductor plays a crucial role in the cable design. The higher the size of the cross section, the higher the copper amount.

The reaction of a cable when subjected to direct or alternating current flow can differ according to the cable design. Unfortunately there are many inferior cables in the market today, and they can be hard to identify.

Which cable components are critical?

When it comes to electrical current the key component is:

  • The conductor: the core of the cable that transfers energy or signals from point to point.


The cross section of a cable conductor plays a crucial role in the cable design. This cross section is represented as an AWG measurement (American Wire Gauge). What makes it tricky is that there is a wide tolerance between the different AWG sizes. Inferior grade cables can often show a comparable AWG in their basic specification but record very  different DC resistance or impedance results.

 

For example:

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Cable Design 1              

AWG 26
Cross section: 0.126 mm2
R_dc = 144 Ohm/km

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Cable Design 2               

AWG26
Cross section: 0.140 mm2
R_dc = 127 Ohm/km

Due to the wide tolerance between AWG standards, it is possible for two cable designs showing the same AWG to record two different DC Resistance results.

What is the risk of electrical current?

Cable conductors that oppose or resist electrical current in an application can overheat, degrading the protective insulation resulting in fire ignition, fatalities and equipment damage.

What is the effect of electrical current on sub-standard cable?

If the opposition or resistance is too high for the current that is travelling through the conductor, the conductor can overheat, causing degradation of the insulation.

What risks does this pose to a building or system?

  • Signal distortion: due to too much resistance for the current in the conductor.
  • System failure: breakdown of the cable's protective conductor insulation can lead to decreased signal transmission and even a complete system breakdown.
  • Fire hazard: gradual erosion of the protective layers of cable insulation will eventually give way to the heated copper conductor and ultimately become a source of fire ignition.
  • Major maintenance and repair costs: disintegrated insulation will lead to failure of the cable and eventually the complete system, requiring costly maintenance as a result of re-installation of the cabling.