Shielded vs Unshielded Cable Explained

 October 16, 2023 |  4 minute read time

STP or UTP? The bottom line for IT professionals.

David Posner

When installing or updating your network infrastructure, there are a variety of network patch cable types to consider. Among the choices to be made is whether to install shielded twisted pair cables (STP) or unshielded twisted pair cables (UTP). Twisted pair cabling consists of two conductors of a single circuit twisted together to help reduce electromagnetic interference (EMI) or “noise”.

A key factor in this decision is an analysis of how prevalent electromagnetic interference (EMI) will be in the installation environment. EMI is commonly caused by nearby motors, generators, air conditioners, and even office mainstays such as fluorescent lights and printers. EMI can cause crosstalk** between circuits, resulting in degradation of data, increased errors and slower transmission rates.

** Crosstalk is the unintentional transmission of a signal from one cable to another.

STP vs. UTP Ethernet Cable

Cat6 shielded vs unshielded

While even UTP (UTP: unshielded twisted pair) cables reduce some EMI, STP (shielded twisted pair) cables more effectively block interference. Cat5 and Cat6 shielded cables are augmented with a thin foil that serves to block EMI. STP cables are ideal for high-speed networks such as data centers where 10GBase-T networks are used because 10G Ethernet is significantly more sensitive to EMI. Properly installed high-quality shielded cables automatically suppress EMI and crosstalk, helping to ensure data integrity and high-speed performance.

High-quality shielded Ethernet cable includes a drain wire to provide grounding that cancels the effects of EMI. However, the cable will only be grounded if jacks and couplers used in the installation are also shielded. Therefore, it’s essential to use shielded jacks and couplers throughout your STP installation to maintain the benefits of STP cabling.

Shielded vs Unshielded Cable

Shielded is more expensive than unshielded Ethernet cable and more difficult to install; it’s stiffer, making it less flexible. The cable also has a larger diameter, taking up more space in conduit. UTP, on the other hand, actually provides faster transmissions in the absence of EMI. It’s less expensive to purchase, easier to install and has been the standard for many years, so it’s already in place in most existing installations.

Regardless of whether you choose UTP or STP, make sure to install high-quality cabling. The better the quality of the cables used, the more years of service you will get out of the installation, reducing long-term replacement and labor costs.

Cat 8 Shielded Cable

Cat 8 is the latest category cable standard to be defined by IEEE. It features the fastest data transfer rate of any copper cable thanks to its use of shielding to virtually eliminate electromagnetic interference (EMI), resulting in fewer errors. In a Cat 8 cable, each twisted pair is foil wrapped, then the four twisted pairs are also wrapped in a braided shielding.