Why Cable Selection Matters
A cable assembly is only as reliable as the cable at its core. Selecting the wrong conductor gauge, insulation material, or shielding approach can lead to premature failure, intermittent connections, or outright safety hazards.
In industrial environments — where vibration, temperature extremes, and chemical exposure are everyday realities — getting the specification right at the design stage prevents costly field failures and product recalls.
Conductor Gauge and Current Capacity
The conductor cross-section (measured in AWG or mm²) determines how much current the cable can safely carry. Under-sizing causes resistive heating; over-sizing wastes material and makes assemblies harder to route.
For most low-voltage signal cables, 22–26 AWG is sufficient. Power cables typically range from 18 AWG for light loads up to 10 AWG or larger for high-current applications. Always derate for ambient temperature — a cable rated at 10 A in free air may only safely carry 6–7 A inside an enclosed panel.
Insulation Materials Compared
PVC is the most common and cost-effective insulation, suitable for temperatures up to 80°C. For higher temperatures, silicone rubber (up to 200°C) or PTFE (up to 260°C) is preferred.
In environments with oils or fuels, thermoplastic polyurethane (TPU) offers excellent chemical resistance. For outdoor or UV-exposed runs, cross-linked polyethylene (XLPE) resists degradation far better than standard PVC.
Low-smoke zero-halogen (LSZH) insulation is increasingly specified for enclosed spaces — including data centres and rail vehicles — to minimise toxic fume risk in the event of fire.
Shielding for EMC Performance
Electromagnetic compatibility (EMC) is critical in applications where sensitive signals run alongside power cables. Braided copper shields offer the best combination of flexibility and coverage (typically 85–95%). Foil shields provide 100% coverage but are less flexible and more prone to fatigue in dynamic applications.
For the highest performance, a combination of foil and braid (known as a double shield) is used. This is common in medical device cables and precision instrumentation.
Environmental and Mechanical Considerations
Beyond electrical performance, consider the cable's operating environment:
• Flex life — if the cable moves repeatedly (e.g. robotic arms, cable tracks), specify a high-flex design with stranded conductors and flexible jacket materials.
• IP rating — in washdown or outdoor environments, the complete cable assembly (including connectors) must meet the required ingress protection rating.
• Chemical exposure — identify any solvents, coolants, or cleaning agents the cable will contact and choose jacket materials accordingly.
• Temperature range — specify both continuous operating temperature and any short-term excursions the cable must survive.