Shielded Wire vs Unshielded: How to Choose

FACTS CHECKED BY  Jose George​

When you update or install your network infrastructure, you must consider different network patch cable types. There are two main types: twisted and untwisted pairs. In twisted pairs, two conductors of a single circuit twist together. In contrast to an untwisted or single conductor pair, a twisted pair reduces electromagnetic radiation.

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Additionally, it reduces the cross-talk between adjacent pairs and the penetration of external EMI. Sometimes, the twisted pair has a shield that offers more immunity to noise. You must know about shielded wire vs unshielded wire to make a better choice.

Image: twisted electric cables

Shielded vs. Unshielded Wire: Definition

The cables with shields are shielded twisted pairs and without shields are unshielded twisted pairs. 

Shielded Cables

shielded twisted-pair cables (STP) have a metal sheath or foil wrapped around each insulated pair of wires, and sometimes, there is multiple wrapping to offer double protection. It enhances the integrity of signals by preventing EMI and other technical issues.

Unshielded Cables

Unshielded twisted-pair cables (UTP) are individual wire pairs that do not have any additional protection layer. These cables are suitable for offices as there is less traffic in such environments. 

Image: electric or data-stranded cables with copper conductor

Shielded vs Unshielded Wire: Basics 

Why do we need shields?

Effects of EMI

Electromagnetic interference in different industry applications can disrupt the working of other equipment. A cable works as a source and a receiver to transfer EMI. When a cable acts as a source, it either conducts noise to other equipment or radiates it as an antenna. A cable picks up the EMI from different sources as a receiver. 

A shielded cable can either reflect the EMI as energy or can pick it up to conduct it to the ground. As a result, the EMI does not reach the conductors. However, still, some energy manages to pass through the shield, but it is too weak to cause any interference.

On the contrary, an unshielded cable does not protect from EMI. As a result, you may notice high electromagnetic interference and cross-talk in a UTP.

Various degrees of shielding

A cable can have varying degrees of shielding and, accordingly, different degrees of effectiveness. The amount of shielding depends on the electrical environment it will be used in, cable diameter, weight, flexibility, and the cost of the cable. There are two types of shields, i.e., foil and braid.

Foil shield: 

It is a thin aluminum layer attached to the polyester of the cable. The carrier, like polyester, gives strength and ruggedness to the cable. A foil shield provides 100% coverage. However, it isn’t easy to apply a connector due to its thin nature. Generally, technicians use drain wire to terminate the shield rather than grounding the entire shield.

Braid shield:

It is a woven mesh of tinned copper wires wrapped around the conductors. You can quickly terminate this shield when applying a connector through soldering/crimping. However, these shields do not offer 100% coverage. A braid shield has some gaps. Depending on the tightness of the mesh, it can offer 75-90% of coverage. However, the coverage does not matter much as the copper conducts the noise better than aluminum and provides better shielding than the foil shield. The braid comprises copper, which adds size and cost to the cable. 

Multiple shielding:

Sometimes, this cost increases as you need multiple shielding layers for noise environments. A foil shields the individual wire pairs, while a foil or a braid protects the overall cable.

In such cables, each shield overcomes the limitations of the other and enhances the performance.

Practical Guidelines for Effective Shielding

  • First, pick a cable with a proper shield suited for your application needs. You may need a foil-braid shield in noise environments, while a foil shield in moderately noisy environments is also enough.
  • If your cable undergoes repeated flexing, a spirally-wrapped shield is a better option. Foil-only shielding is not successful in such cases as repeated flexing can tear the shield.
  • Always check that the connection between the ground point and equipment is proper.
  • Ensure that the connector also offers shielding protection similar to that of cable.
  • Ground the one end of the cable to remove noise, creating ground loops.

Abbreviations used to describe cable shielding

AcronymDescriptionCable shieldingPair shielding
UUnshielded
FFoil shielded
SBraided shield
TPTwisted pair
UTP or U/UTPUnshielded twisted pairnonenone
F/UTPOverall foil shieldAL Foilnone
U/FTPEach pair shieldednoneAL foil
S/FTPEach pair and overall shieldTC braidAL foil
SF/UTPOverall shield (foil+ braid)AL Foil+ TC braidnone
F/FTPEach pair shielded + overall foil shieldAL foilAL foil

Shielded vs. Unshielded Wire: Similarities

  • Both cables have RJ45 connectors.
  • Both cables have a total of eight wires twisted in four pairs.
  • There is a ripcord to open the cable jacket in both the cables.
  • Both cables terminate based on the TIA 568A or B standards.
  • The function of both cables is similar, i.e., delivering data signals and power over ethernet from point A to Point B.
  • Both cables may have splines. This cross-shaped skeleton keeps the twisted pair intact and separates them from others.

Shielded vs. Unshielded Wire: Differences

  • Shielded cables are difficult to install due to their thickness and overall construction.
  • Shielded cables are expensive and need costly hardware to work as intended compared to unshielded cables.
  • STP has shields of aluminum foil, aluminum braid, or both, while unshielded does not have such shields.
  • Shielded cables have a drain wire to radiate static electricity accumulated in the cable. Unshielded cables do not have such wires.
  • If not grounded properly, shielded cables may cause issues.

Shielded vs. Unshielded Wire: How to Make Your Choice?

While picking ethernet cables for homes or businesses, you must evaluate the cost and the environment to decide which cable types you must choose.

  • If they do not hear power lines in homes or small businesses and do not have heavy appliances, You can use unshielded cable.
  • In a complex environment with heavy machinery such as elevators, fluorescent lights, etc., you need shielded cables as these pieces of machinery generate intense EMI.
  • In areas with high proximity of high voltage panels, you need shielded cables.
  • In equipment near generators and electric motors. You need shielded cables.
  • In critical backbone connections. You need shielded cables.
  • Apart from these, you must consider the cost and installation ease of the cables.
  • Shielded cables are expensive, but with price, you also get the speed and security of the network.
  • Further, unshielded cables are easier to install and do not require any grounding, while shielded cables are stiff thus challenging to install.

Image: twisted-pair ethernet UTP

Conclusion

All the ethernet cables have sequential numbering that puts them in different categories based on different specifications. According to the need of the transmission speed, you can choose a cable type from a category. For instance, the Cat5e Ethernet cable can support 1000 Mbps, while the latest Cat 8 cab supports 25.40Gbps. Whether you need a shielded or unshielded cable depends on your application. If you are still uncertain about what cable type to choose, please contact us.

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