Cable shielding, (or screening), can be composed of a metallic braid, or metallic or polyester foil. The shielding can be either wrapped around all 4 pairs of twisted pair cable, just the individual conductor pairs, or both the entire cable and individual pairs. In a shielded product code, the letters preceding the slash are equivalent to the shielding on the whole cable; the code after the slash is equivalent to the shielding for the individual pairs. For example:
As a guide, if you have motors or generators placed next to network cables, EMI and RFI can reek havoc with data transmission on a copper cable. This will result in data errors, and quite possibly downtime. In order to wipe out EMI/RFI interference, you will need to go for shielded cables and connectors.
As you can see from the list below, there are fundamentally two types of cable shields: braided and foil. Which option you plump for will depend on your application.
Here is a glossary of terms to help you decode cable shielding:
- FTP – Foiled Twisted Pair : An additional layer of protection is created with shielding/screening wrapped around the individual twisted wires.
- STP – Shielded Twisted Pair : Braided shielding wrapped around the individual twisted wires adds a layer of protection.
- F/UTP – Foiled/Unshielded Twisted Pair : An overall foil shield encases the 4 pairs of unshielded twisted pair. Commonly used in 10GBaseT applications.
- S/UTP – Shielded/Unshielded Twisted Pair : An overall braid shield is wrapped around all 4 pairs of unshielded twisted pair.
- SFTP – Shielded and Foiled Twisted Pair : Foil shielding around the individual twisted wires and an overall shield that is sometimes a flexible braided shield. This provides the highest level of protection from interference.
- SF/UTP – Shielded and Foiled/Unshielded Twisted Pair : Both an overall braid screen and foil shield with unshielded twisted pairs. Occasionally referred to as an STP cable, these cables are very effective at protecting EMI/RFI from entering or exiting the cable.
- S/FTP – Shielded Foiled/Twisted Pair : An overall braid shield with foil-shielded twisted pairs. The shield underneath the jacket is a braid and each individual pair is surrounded by its own foil shield. The purpose of the additional foil on individual pairs is to limit the amount of crosstalk between them.
- F/FTP – Foiled/Foiled Twisted Pair : An overall foil shield with foil screened twisted pairs. Like F/UTP, this cable is commonly used in 10GBaseT applications.
- U/FTP – Unshielded/Foiled Twisted Pair : No overall shielding or braid with foil-shielded twisted pairs. This cable is also frequently used in 10GBaseT applications.
- U/UTP (UTP) – Unshielded/Unshielded Twisted Pair : Pairs of wires twisted together that are not shielded at all. These cables are often referred to as UTP andare one of the most basic methods used to help prevent electromagnetic interference.
