Shielded vs Unshielded Industrial Cables: Which Should You Use?

I. Shielded Cable vs Unshielded Cable: Key Differences

II. Selection Decision Guide: When Must Shielded Cables Be Used?
1. Harsh electromagnetic environment (mandatory use of shielding)
· Near frequency converters and servo drives: This is the biggest interference source in industrial environments.
· Around high-power motors, relays, and welding equipment.
· In areas close to radio transmission sources or high-voltage power lines.
2. Sensitivity Signal Transmission
· Analog signals (such as 4-20mA, 0-10V sensor signals): Even slight interference can cause the reading to fluctuate.
· High-frequency signals (such as Profinet, EtherCAT, Ethernet): The shielding layer is the key to ensuring communication speed and stability.
· Low-level signals (such as thermocouples, RTD).
3. Long-distance wiring
· The longer the wire, the more pronounced the antenna effect becomes, and the easier it is to pick up noise. For signal lines longer than 10 meters, it is recommended to use shielded wires first.
4. Safety and Compliance Requirements
· Circuits related to safety systems (such as emergency stop buttons, safety relays).
· Scenarios where shielding is mandatory as per industry standards (such as TIA-1005 industrial environment standards).

III. When can non-sheathed cables be used?
· Short-distance jumper wires (less than 1 meter) inside the control cabinet.
· Dry and clean office or laboratory environment.
· Pure DC power supply or non-critical digital signals (such as indicator light circuits).
· Situations with extremely limited budget and very low risk of interference (risk of unstable signals needs to be accepted).

IV. Key Precautions for Shielding Wire Installation
Choosing a shielding wire does not guarantee a perfect result. Incorrect installation can nullify the shielding effect:
❌ Un-grounded shielding layer: This is the most common mistake. The shielding layer must be reliably grounded to achieve the "Faraday cage" effect.
❌ Grounding at both ends (forming a ground loop): Low-frequency signal lines (such as RS-485) should be grounded at a single point; otherwise, the potential difference between grounds will cause current noise.
❌ "Pigtail" connection of the shielding layer: Wrapping the shielding layer into a single strand and then grounding it will significantly increase the high-frequency impedance, severely weakening the shielding effect. Use 360° crimping-type shielding terminals (such as DB9 metal casings, dedicated grounding clips).
❌ Floating shielding layer: An ungrounded shielding layer is not only ineffective but may also become an antenna to collect noise.

V. Quick Reference Table for Practical Model Selection

VI. Summary
Selection rules for industrial environments:
☆   High interference, weak signal, long distance → Must choose shielded;
☆   Clean environment, tight budget, short distance → Prefer non-shielded.