By Eileen Harvey
Industrial Ethernet networks are the nervous system of modern manufacturing plants, automation lines, oil and gas facilities, and other mission-critical environments. In these high-stakes applications, reliable data transmission is non-negotiable. Even a brief disruption can cause production downtime, safety risks or expensive equipment failures.
One of the most common questions industrial network engineers face is: Should we use shielded cables for our industrial Ethernet installation?
In most industrial environmentsꟷyes, shielded cables are strongly recommended. However, the decision depends on the electromagnetic environment, installation constraints and your performance needs. In this guide, we’ll explore the differences between shielded and unshielded Ethernet, when to use each and best practices for installation.
Shielded vs. Unshielded Ethernet Cables
Ethernet cables consist of twisted copper wire pairs designed to transmit data using electrical signals. The twists in the pairs help reduce crosstalk (interference between pairs), but in noisy environments this isn’t always enough. That’s where shielding comes in.
Shielded twisted pair (STP) includes an additional conductive layer around each twisted pair or around all pairs combined. This shield can be foil (F), braided wire mesh (S) or both (SF). Shielding helps block electromagnetic interference (EMI) and radio frequency interference (RFI).
Unshielded twisted pair (UTP) relies solely on the twists for noise rejection, making it adequate for low-interference settings like offices, but less robust in industrial conditions.
For a wide selection of both shielded and unshielded options, see Industrial Ethernet Cables – L-com.
Why Industrial Environments Are Different
Unlike office buildings, factories and industrial facilities are full of EMI sources. These include large electric motors, variable frequency drives (VFDs), high-voltage power lines, welding equipment and relay-based control systems.
These devices generate strong electromagnetic fields that can induce noise in Ethernet cables, causing packet loss, data retransmissions, network slowdowns and unreliable machine-to-machine (M2M) communications.
In real-time control systems, such as those using EtherCAT or PROFINET, even minor delays can cause major operational disruptions. This is where shielded cables are not just an upgrade, but a necessity.
The Benefits of Shielded Ethernet in Industrial Settings
Let’s examine four benefits of shielded Ethernet cables. The first is enhanced noise immunity. Shielding forms a conductive barrier that reflects or absorbs unwanted signals before they reach the data conductors.
The second benefit is stable performance over longer distances. In high-noise areas, shielded cables maintain high-speed data integrity for runs approaching the 100-meter Ethernet limit.
The third benefit is that shielded cable complies with industry standards. Many industrial networking specifications recommend or require shielding, especially for gigabit or faster connections.
The fourth notable benefit is reduced downtime. Cleaner signals mean fewer dropped packets, less troubleshooting and more predictable network behavior.
When You Absolutely Need Shielded Cables
Following are five conditions that should make you seriously consider shielded Ethernet: cables run parallel to high-voltage power lines for extended distances; the facility has heavy electrical machinery operating nearby; your network operates at 1 Gbps or higher speeds in an industrial area; you use precision motion control or SCADA systems where data loss is unacceptable; and you must meet strict Electromagnetic Compatibility (EMC) regulations.
When Unshielded Might Be Enough
Not every industrial Ethernet cable needs to be shielded. UTP can work in control rooms with minimal EMI sources, short patch cable runs inside shielded cabinets, and applications under 100 Mbps in low-noise areas. However, most mixed-use plants still benefit from standardizing on shielded cabling to simplify inventory and ensure network resilience.
Types of Shielding and Their Uses
Industrial Ethernet cables come with several shielding configurations: F/UTP means foil shield is around all pairs, which is good for general EMI protection; S/FTP indicates that each pair is individually shielded with foil plus an overall braided shield, which is best for extreme EMI environments; and SF/UTP meansthere is an overall foil plus a braid without individual pair shields, which is strong all-around shielding.
For more detail on construction options, see Industrial Grade Cables – L-com.
Installation Best Practices for Shielded Cables
A shield is only as good as its installation. Follow these guidelines:
- Proper Grounding: Shielding must be grounded to safely dissipate interference. Usually, grounding is done at one end to avoid ground loops, though some standards recommend grounding at both ends.
- Avoid Parallel Runs with Power: If possible, run Ethernet cables at least 12 inches away from high-voltage lines. If crossing is necessary, do so at a 90° angle.
- Use Shielded Connectors: RJ45 connectors for shielded cables have a metal shell to maintain shielding continuity. A good example is Waterproof Shielded RJ45 Connectors – L-com.
- Maintain Shield Continuity: During termination, ensure the foil/braid makes good contact with the connector’s metal housing.
Environmental Considerations Beyond Shielding
While shielding protects against EMI, industrial cables also face chemical exposure (oil, solvents, corrosives), mechanical abrasion, temperature extremes, and UV radiation for outdoor runs. This is why jacket materials like PUR or TPE are common in industrial Ethernet. For chemical resistance, see Oil & Chemical Resistant Cables – L-com.
Cost vs. Performance Trade-off
Shielded cables cost more than UTP due to added materials and complexity in installation. However, the ROI in uptime and reduced troubleshooting often outweighs the price difference, especially in plants with high production costs.
For most industrial Ethernet applications, shielded cables are the safe, future-proof choice. They provide superior noise immunity, help ensure compliance with EMC regulations and support high-speed data integrity in electrically noisy environments.
If your facility has significant EMI, high-speed network demands or critical control systems, investing in shielded cabling will pay off in stability, reliability and fewer headaches.
