Editor’s Note: This blog was originally published on July 23, 2015. Since then, it has received lots of great feedback and reader comments – including questions about where each shielded cable type can be used. So we updated this piece in August 2019 to include that information! Read on to discover details about when and where you should use these shielded cable types.

Like a shield used during battle, cable shielding acts as a barrier that protects the cable from external threats, such as electrical interference (EMI) and RFI (radio frequency interference). It also prevents cable signals from interfering with surrounding cables and equipment.

STP Cable

While not all environments demand such a robust cable, shielding is becoming more common. When it first became available, shielded cables were used in areas such as factory floors, areas with high concentrations of electrical equipment and secure communications applications. Today, shielded cable is prevalent in many different applications, including government, healthcare and even education. 

When selecting a shielded cable, there are three considerations to keep in mind:

  1. Shielding effectiveness
  2. Flexibility
  3. Ease of connectorization

Once you know how important each of these things is to you, you’ll know which shielded cable type will work best.

There are many acronyms used to describe shielded cables, from STP to F/FTP; while many are often used synonymously, nearly all of them have different meanings. This blog provides basic information about each style, as defined by ISO/IEC 11801:200, to clear up the confusion. Now you can compare choices like UTP vs. FTP cable or STP vs. FTP cable.

  1. F/UTP (FTP)

    An overall foil shield (F) with unscreened twisted pairs (UTP)
    This cable is very much like common UTP cable, with the addition of foil underneath the main cable jacket. Another common name for this cable is “FTP.” F/UTP cables are common in 10GBaseT applications. They’re easier to terminate than some other shielded cable types, but they aren’t quite as flexible because the foil tends to be stiffer.

    Use F/UTP in high-frequency applications that require some cable flexibility.

  2. S/UTP

    An overall braid screen (S) with unscreened twisted pairs (UTP)
    This is occasionally referred to as an STP cable, but beware: There are other shielded cables among this list that may also claim this term. To be sure, always check to see whether your cable will have any kind of overall barrier and whether the individual pairs have their own shield.

    Use S/UTP in low-frequency applications that require some cable flexibility and easy connectorization.

  3. SF/UTP

    Both an overall braid screen (S) and foil shield (F) with unscreened twisted pairs (UTP)
    This cable is also occasionally referred to as an “STP cable.” Cables with an overall braided screen are very effective at preventing EMI from entering or exiting the cable.

    Use SF/UTP cable when you need protection from low- and high-frequency noise interference. It supports easy connectorization and is moderately flexible. The primaries are not foiled.

  4. S/FTP

    An overall braid screen (S) with foil screened twisted pairs (FTP)
    The “shield” underneath the jacket is a braid, and each individual pair is surrounded by its own foil barrier. The purpose of the additional foil on individual pairs is to limit the amount of crosstalk between them. This type of cable can be harder to install because of the amount of metal that must be removed to install a connector. The braid and stranded conductors inside help maintain flexibility fairly well.

    Use S/FTP cable when you need protection from low- and high-frequency noise interference. It’s easy to install and is moderately flexible. All primaries are foiled.

  5. F/FTP

    An overall foil shield (F) with foil screened twisted pairs (FTP)
    Similar to F/UTP cables, these shielded cables are commonly used in 10GBaseT applications.

    Use F/FTP cable when you need high levels of shielding from high-frequency noise interference and aren’t worried about ease of installation (it offers little to no flexibility) or the time it takes to install connectors.

  6. U/FTP

    No overall shielding or braid (U) with foil screened twisted pairs (FTP)
    This type of shielded cable is commonly used in 10GBaseT applications as well.

    Use F/UTP in high-frequency applications that require some cable flexibility.

  7. U/UTP

    Notice anything wrong here? You caught us! This cable is not shielded at all and is the common unshielded cable most often referred to as UTP cable.

cant ignore cat 6a bannerNow You Know!

Now that you’ve read through these shielded cable types, you can refer to this handy guide to keep them straight. But it can still be confusing to wade through acronyms like STP, F/FTP and FTP cable when selecting the right cable for your project.

If you have any questions, or are looking for a specific shielded cable, Belden can help. Our global facilities produce a variety of shielded cable styles, and our experts can help you find what you need.

To learn more about shielded cable, visit our Shielded Cable Product Bulletin or schedule a call with one of our experts!