Cables are meant to carry electric current safely and efficiently. However, these safety and performance goals can be compromised if a counterfeit cable is produced. The counterfeit cable may result in performance issues such as poor lifespan, or even safety concerns such as overheating and increased risk of electrical shock or fire.
Counterfeit or fake cables are by definition cables that falsely claim that they are compliant with safety and performance standards when they are not. This may include marking on the label that they are produced to certain international or national standards even though they do not fulfill them.
We have deconstructed the two basic components that determine the quality of the cable:
Copper amount is inadequate
The most obvious method to decrease the cost of producing a cable is by decreasing the amount of the largest cost component, which is the copper conductor.
This can be accomplished by either under sizing the cross-sectional area (“CSA”) of copper conductor or by using impure copper.
Under sizing the CSA of copper conductor can be accomplished by reducing the number of strands or by reducing the individual diameter in conductor. Impure copper means using less than 99.9% copper content, or other material, like copper alloy or even copper-plated aluminum. Either method will result in an increase in the cable’s conductor resistance above the maximum value, specified in the relevant standard.
Conductors with higher resistance may pose a safety threat. When current passes through a conductor, the inherent resistance causes a larger heating effect. Also, the heat of the conductor may cause the premature failure of the insulation which may result in a short circuit or even an electrical fire.
Conductor resistance test can measure the adequacy of the CSA of copper conductor in a cable. Voltage is applied across a sample length of cable and the current across the sample is measured. Using Ohm’s law, the resistance of the sample can be calculated. If the measured resistance is higher than the specified maximum value, the CSA of copper conductor is inadequate.
Low grade material compound
Much like the conductor, substandard cables can result from a reduction in the quantity and quality of insulation material used. Less quality insulation can result in lower rated voltage. Cheaper cables also may have worse additives added to the insulation and/or sheath material. This may result in decreased cable flexibility, decreased insulation resistance, and increased susceptibility to cracking of the insulation or sheath with age.
There are many material properties that are important to test for. Here we highlight two basic types that are important to know as an introduction.
Insulation resistance test measures the current leakage from the cable, verifying that the conductor is sufficiently insulated from the environment. Poor insulation may result in short circuit, electric shock, or fire. Usually this test is carried out at the maximum conductor temperature under normal operations. This maximum operating temperature is determined by the material type used in insulation and/or sheathing. The higher the insulation resistance, the better the cable is well insulated from the environment.
Tensile strength and elongation tests measure the mechanical properties of the insulating and sheathing compound. The tensile strength of a material is the amount of force needed to pull that material to the point of breaking. Elongation is a measure of the length that the material can be stretched to before breaking.
The cable material is tested at two time points. Once after the manufacturing of the cable and the other after accelerated ageing by subjecting the material according to a specified temperature and duration. The tensile strength and elongation tests are repeated after ageing to give an appreciation of how ageing affects the mechanical properties of the materials.
Due to the larger variety of potential issues with insulation and sheath, there are correspondingly more tests required to ensure quality. What we have described here is just a small set of basic but important tests that are conducted on all types of cables, but additional tests are required to ensure other claimed material properties are fulfilled. These include tests of the cable’s fire resistance, water resistance, behavior under thermal stress, and flexibility.
In summary, counterfeit cables make a claim of complying with international or national standard, but in fact skimp on either CSA of copper or the quality of insulation and/or sheath materials. However, there is no direct way to identify a counterfeit cable as it requires a full set of lab tests, and therefore it is important to trust the brand of the cable you are purchasing. Buying from a reputable cable brand with products certified by third party will ensure the longevity and safety of product down the road as you will not have to worry about replacing it sooner than the shelf life.