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EMI Protection For Cables: Which Is Better – Shielded Or Unshielded?

by | May 22, 2023

Have you ever experienced static during a phone call? That’s just one example of Electromagnetic interference EMI, also known as radio frequency interference (RFI). EMI/RFI is an electronic disturbance caused by external sources such as electromagnetic radiation, electrostatic coupling, or electrical noise.

Unfortunately, it’s all around us and can interfere with data traffic in networking. When the EMI is strong enough, it can cause data loss, slow the network, or interrupt data paths completely. Such interference can lead to an increased error rate or a complete loss of information.

So, one critical part cable and wire harness manufacturers must consider- providing electromagnetic interference protection during operation, which can be accomplished using shielded or unshielded components. In this blog post, we will examine why both types of components are used and their benefits and effectiveness in providing EMI protection from various sources.

What Are Shielded Cables?

Shielded cables have individual wires encased in a shield, such as foil, to prevent interference from electrical noise or electromagnetic radiation. These foil-shielded cables are wrapped one more time to offer double protection. The shielding aids in preventing EMI and other technical issues that can affect signal integrity.

The four pairs of wires in a bundle that makes up a cable are often twisted together to prevent crosstalk interference from the other wire pairs in the bundle. Shielded twisted pair cables or STP cables provide additional protection against electromagnetic interference that can disrupt the transmission of important data.

There are 3 different shielding configurations, each with its levels of protection, such as braided cables (90% shielding), spiral (98% shielding), and metal-coated mylar or foil cables (100% shielding). Companies that are experienced cable manufacturers such as Violin Technologies supply the best custom cable assemblies.

Advantages of shielded cables

  • Have an additional layer of protection that improves noise immunity and EMI resistance.
  • They are better suited for high-noise environments or scenarios where electrical devices may interfere with data transmission.
  • Tend to be heavier and more expensive.
  • Improve overall performance for data transmission in EMI-prone situations.

Different Types of Shielded Cables

For reliable signal transmission, shielded twisted pair cabling (STP) minimizes radio frequency and electromagnetic interference caused by other electronic devices and objects.

Shielded cables can feature individual shielding for each twisted pair, all cables collectively, or both. This shielding typically comes in a thin sheet of foil or braided shielding; each type has a designated letter code.


This cable type features a foil shield encompassing the entire cable, with unshielded twisted pairs of woven copper wires inside. While it does provide a basic level of shielding against EMI, the foil shield may be susceptible to damage over time due to the fragile nature of the shielding material.


A cable with a complete foil shield and additional foil shielding around each twisted pair provides almost complete protection against EMI. However, the foil is prone to physical damage over an extended period.


The most frequently used shielded cable has a braided shield surrounding the entire cable and foil shielding around each twisted pair. This cable type offers almost complete shielding while maintaining its strength and flexibility.


The shielded cable is designed with a braid or screen to cover the entire cable. While it does not offer as much protection as foil shielding, it is highly durable and often found in older shielding cables. However, the additional cable and tape shielding weight can make managing it more challenging.


This type of Ethernet cable boasts the most advanced shielding available, featuring double protection with a braided shield and foil shield around the cable and foil shielding around each twisted pair. It provides excellent external EMI shielding, prevents crosstalk, and has a durable braided shield that helps safeguard against future shield damage.


This cable features a braided and aluminum foil shield, both designed to protect the cable from external electromagnetic interference. However, the individual twisted pairs inside the cable remain unshielded and are, therefore, susceptible to crosstalk. Despite this limitation, the combination of shields provides effective overall shielding for the cable.

EMI protection for cables

What Is An Unshielded Ethernet Cable?

Unshielded cables are cables without a shield to protect the wires inside. Instead, they are helically coiled and twisted together during manufacturing to lessen the chance of EMI-related malfunction.

Unshielded cables, commonly known as UTP (Unshielded Twisted Pair Cable), provide equivalent bandwidth, cable types, lengths, and outputs as shielded cables. However, they do not offer EMI protection like their shielded counterparts.

Advantages of unshielded cables

  • They are less expensive and lighter than shielded cables.
  • Because of their tiny diameter and flexibility, they are much easier to install.
  • Faster information transmission (with no EMI present).
  • Many industries have already adopted this standard.

When To Use Shielded Cables

Shielded cables are highly valuable in industrial environments prone to electronic interference, such as radio stations and airports. STP cables are also used in security systems to safeguard against power frequency and radio frequency interference to lessen the frequency of false alarms, which could otherwise be disturbing. They are also used in public address systems or recording studios.

Apart from shielding external interference, the foil-shielded cables also prevent noise from escaping, reducing the possibility of causing interference in other devices. Experienced vendors like Violin Technologies provide the best cable management solutions for shielded and unshielded cables.

When To Use Unshielded Cables

Shielding is not used in an Unshielded Twisted Pair cable to minimize disruptions. Instead, the cable’s pairs are twisted to limit electromagnetic interference. UTP cables are commonly used for office LANs and similar network cabling systems because they are versatile, inexpensive, easy to install, lightweight, and flexible.

However, UTP cables are susceptible to electromagnetic and radio frequency interference and have a smaller bandwidth when compared to coaxial and fiber optic cables.

Shielded Vs. Unshielded Cables

Shielded cables provide nearly complete protection against electromagnetic interference (EMI), minimizing interruptions in video streams and ensuring more reliable data transfers. However, they are more costly, thicker, heavier, and less flexible, demanding extra shielding hardware and grounding wires. Also, because the shield must be properly grounded, they can be more difficult to install than unshielded cables.

On the other hand, unshielded or UTP cables are more affordable, simpler to install, and lighter, making them a more practical option for many users. Even though they offer less EMI shielding, they are still commonly used and may be sufficient for expanding an existing network built with unshielded cables.

Violin Technologies As Trusted Cable Assembly Suppliers

The intended application ultimately determines whether shielded or unshielded cabling should be used. As a cable assembly manufacturer, Violin Technologies excels in providing comprehensive services, including engineering, design, test development, manufacturing, and prototyping. Their expertise in these areas is unmatched, ensuring you receive top-quality products and services.

Please contact us if you need assistance choosing between shielded and unshielded cables for your electrical system.

Aparna Sushumna | Author

Aparna Sushumna

About the Author

Aparna Sushumna, a mother to a hyperactive toddler who is all over the house. I aspire to be a decent content developer. A Bachelorette of technology says my qualification but I anticipated being a singer. Thanks to the recession, I dwelled into various jobs, from coding to being a tech support executive to a help desk professional, only to conclude that there is something else I wish to do. Here I am to accomplish my profound passion for content writing. Music, nature, jewelry, beauty, mythology, life quotes, celebs, and their life, being my areas of interest.