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Guide

Industrial Ethernet cabling and EMC: practical rules

Practical rules for industrial Ethernet cabling: cable category, connectors, shielding, grounding, segregation from power cables, and length limits.

  • 5 min read
  • Updated

Cable and connectors

  • Use industrial-grade shielded cable (Cat5e or better) with flexing and oil-resistant jackets where needed.
  • Use rugged connectors such as M12 for machine-level devices, and RJ45 industrial variants inside cabinets.
  • Copper Ethernet links are limited to 100 metres per segment. Use fibre or a switch beyond that.

Reducing electrical noise

  • Keep Ethernet cables separated from power, motor and VFD cables, and cross them at right angles when necessary.
  • Bond the cable shield to the cabinet earth where the cable enters, with a full 360-degree clamp.
  • Use shielded motor cable for drives and ground its shield at both ends.
  • Use fibre optic cable for long runs, between buildings or where noise is severe.

Network design basics

  1. Use managed industrial switches rated for the temperature and vibration.
  2. Separate the control network from the office network with a firewall or DMZ.
  3. Label every cable and keep a network diagram.
  4. Test links after installation with a cable tester.

Frequently asked questions

How long can an Ethernet cable be in a plant?

A copper twisted-pair link is limited to 100 metres per segment. For longer distances use a switch or fibre.

Should I ground the shield at both ends?

Shielded data cables are commonly grounded where they enter the cabinet, with a proper 360-degree contact. Follow the manufacturer's guidance for your installation.

Why separate data and power cables?

Power and motor cables carry high-frequency noise that can couple into data cables and cause errors.

This guide is general engineering guidance. Always confirm part-specific details, ratings and compatibility against the manufacturer’s datasheet. We confirm price, stock and specifications for the exact part in a written quotation. See the glossary for the terms used here.