Cat.6A U/FTP, S/FTP or F/FTP cable?

When designing a Category 6A structured cabling system, the use of a U/FTP, S/FTP or F/FTP cable construction is not, in itself, the decisive factor in meeting the relevant standards. What matters is that both the cable and the entire transmission channel meet the required transmission performance, alien crosstalk (AXT) and electromagnetic compatibility (EMC) parameters defined by the applicable international and European standards, such as ISO/IEC 11801, IEC 61156 and EN 50173.

Compliance with these parameters is essential for the reliable operation of all standardised transmission protocols, including 10GBASE-T. For the cable itself, compliance with the applicable requirements must be demonstrated by a valid component-level certificate issued by an independent testing laboratory.

The quality of the installed cabling system is subsequently verified by certification testing using a measurement instrument with Level IIIe accuracy and valid calibration.

S/FTP cables with overall braided shielding are primarily intended for environments with high levels of low-frequency electromagnetic interference, for example near high-power electrical switching equipment. Such conditions typically occur in industrial or energy-intensive environments, where resistance to high-frequency interference alone is not sufficient and effective protection against the low-frequency magnetic component of electromagnetic interference is also important.

The shielding effectiveness of data cables is evaluated by the IEC 61156 series of standards, including IEC 61156-5 and IEC 61156-9, using the coupling attenuation parameter. From an electromagnetic compatibility perspective, ISO/IEC 11801 and EN 50174 classify environments into three categories: E1, E2 and E3.

Class E1 covers typical administrative and office environments, where the standard generally requires a coupling attenuation of at least 26 dB for the transmission channel at 500 MHz. Class E2 covers light industrial environments, where the minimum requirement is 36 dB.

The typical coupling attenuation of Cat.6A U/FTP cables at 500 MHz is approximately 55 dB, depending on the manufacturer’s specification. A transmission channel constructed using such a cable therefore provides a substantial performance margin over the standardised requirements for both E1 and E2 environments.

In terms of resistance to high-frequency EMC interference and alien crosstalk, the benefit of an F/FTP construction compared with U/FTP is marginal. Its effectiveness against interference containing a low-frequency magnetic component is limited, and it is therefore not sufficient for use in E3 environments.

Furthermore, the overall foil shield increases the mechanical stiffness of the cable. If the specified bending radius is not observed, this may contribute to permanent geometric irregularities that can negatively affect impedance uniformity, return loss and crosstalk performance.

Based on the above, the use of high-quality Cat.6A U/FTP cables remains the technically and economically optimal solution for E1 and E2 environments, while meeting the applicable standards and ensuring transmission speeds of up to 10 Gbit/s.

The use of S/FTP cable is generally justified primarily in industrial environments with high levels of electromagnetic interference classified as E3.

Keline team