Category Cable Shielding Types
There are basically two types of Category cable mechanical construction: Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP).
Unshielded Twisted Pair (UTP)
Unshielded Twisted Pair (UTP) cables are the most common type of Category cable. A typical Cat5e, Cat6, Cat6a, and Cat7 cable is comprised of 8 conductors that are twisted into 4 sets of pairs. Each bare copper conductor is insulated and color coded. Each bundle of Category cable twisted pairs is bundled under an overall jacket such as PVC. Each twisted pair of cable has a different twist rate in order to minimize crosstalk within the cable.
UTP cable construction is the most common construction on the market because it is less expenseive than shielded cables and is easier to install. SCP offers UTP for Cat5e, Cat6, and Cat6A.
Shielded Category/Ethernet Cables
Twisted pair cables are often shielded to prevent electromagnetic interference (EMI) or radio-frequency interference (RFI) from affecting the performance of the cable. The shielding protects EMI and RFI from entering or exiting the cable. There are commonly two types of shielding used on Category Cables: Foil Shield and Braided Shield.
A foil shield consists of an Aluminum foil that is wrapped around all of the twisted pairs as an "overall foil shield" or it may be used around each individual pair of wires as "each pair shielded".
A braid shield commonly refers to a "tinned copper braid" as an overall shield for all of the twisted pairs in the cable.
All shielded Category cables have a special grounding wire added called a drain wire. The shielding must be grounded for the shielding to work. Typically the drain wire is placed alongside the foil shield.
Category Cable Shielding Acronyms
The acronyms used to describe the cable shielding have changed over the last several years in order to avoid confusion of the different types of shielding found on Category cables today. The mechanical construction of the Category cables shielding is identified by specific abbreviations. These abbreviations or acronyms were established by the ISO/IEC 11801 standard and adopted by TIA/EIA.
The standard abbreviations are as follows:
- TP = Twisted Pair
- U = Unshielded
- F = Foil Shield
- S= Braided Shield
Example:F/UTP F: Describes the overall shielding type U: Describes the shielding of the pairs TP: Describes the Twisted Pairs The code before the slash describes the overall shielding. The second letter after the slash describes the shielding of the individual pairs.
The chart below indicates the approved Acronym Designation for Category Cable shielding:
Category Shielding Acronym Designations
|Acronym||Description||Cable Shielding||Pair Shielding|
|UTP or U/UTP||Unshielded Twisted Pair||None||None|
|F/UTP||Overall Foil Shield||AL Foil||None|
|U/FTP||Each Pair Shielded||None||AL Foil|
|S/FTP||Each Pair Shielded + Overall Braid Shield||TC Braid||AL Foil|
|SF/UTP||Overall Foil Shield + Overall Braid Shield||AL Foil + TC Braid||None|
|F/FTP||Overall Foil Shield + Each Pair Shielded||AL Foil||AL Foil|