Industrial Cable Assemblies factory

What Safety Standards Apply to Industrial Cable Assemblies in Hazardo...

Industrial settings like oil refineries, chemical plants, grain silos, and paint spray booths contain areas where flammable gases, vapors, dusts, or fibers can be present. Using standard electrical equipment here can trigger explosions. Special safety standards govern everything, including cable assemblies, to prevent ignition sources. Understanding these is critical for safety, compliance, and avoiding costly downtime or accidents.

Why Special Standards Matter in Hazardous Areas

In hazardous areas, an electrical spark, arc, or even excessive surface temperature from a cable or its termination could ignite the surrounding atmosphere. Hazardous area cable assemblies must be designed, manufactured, and installed to eliminate this risk.

Key Standards & Systems

While regulations vary globally, two primary systems dominate:

1. ​The IECEx System (International): Based on the ​IEC 60079 series of standards. This is widely adopted internationally (including Europe under ATEX, Australia, and increasingly other regions).
   • ​Core Standard: IEC 60079-0: General requirements for explosion-protected equipment.
   • ​Key Methods Relevant to Cable Assemblies:
     • ​IEC 60079-7: Increased Safety “e” – Ensures no sparks, arcs, or excessive temperatures under normal operation through enhanced construction and installation practices. Common for terminal boxes and connections.
     • ​IEC 60079-11: Intrinsic Safety “i” – Limits electrical energy (both voltage and current) within the circuit so sparks or thermal effects cannot cause ignition. Requires special cabling considerations (e.g., capacitance, inductance limits). Often used for instrumentation.
     • ​IEC 60079-18: Encapsulation “m” – Seals potential ignition sources within resin. Can apply to cable terminations.
     • ​IEC 60079-14: Electrical installations design, selection, and erection (covers installation practices for cables/conduit).
   • ​Markings: Products certified under IECEx will have “Ex” markings specifying the protection method, gas group, temperature class, and equipment protection level (e.g., Ex ia IIC T4 Ga).
2. ​The NEC/CEC System (North America): Governed by the ​National Electrical Code (NEC) in the USA (NFPA 70, Articles 500-504) and the ​Canadian Electrical Code (CEC). These use a Class/Division/Group system, though an IEC-based Zone system (Articles 505/506 in NEC) is also permitted and growing.
   • ​Division System (Art 500):
     • ​Class I: Flammable Gases/Vapors
     • ​Class II: Combustible Dusts
     • ​Class III: Ignitable Fibers/Flyings
     • ​Division 1: Hazard present during normal operation.
     • ​Division 2: Hazard present only during abnormal conditions (like a leak).
   • ​Zone System (Art 505/506): Similar to IEC Zones (Zone 0/1/2 for gases; Zone 20/21/22 for dusts).
   • ​Key Requirements for Cables/Assemblies:
     • ​Suitability: Cables/conduit must be approved for the specific Class/Division/Group or Zone.
     • ​Sealing: Conduit systems require explosionproof or sealed fittings where they enter enclosures or at specific intervals (Division 1) or where passing between areas to prevent gas migration.
     • ​Cable Types: The NEC/CEC specifies acceptable cable types (e.g., MI Cable, ITC-HL, TC-ER-HL) and installation methods for hazardous locations.

Practical Solutions: Ensuring Compliant Cable Assemblies

1. ​Define the Hazard: Before selecting anything, determine the classification (Zone/Class/Division), gas/dust group, temperature class, and required protection level (EPL) for the specific area the assembly will be used in. Consult the facility’s hazardous area classification drawings and safety documents.
2. ​Prioritize Certified Components:
   • ​Cables: Select cables specifically tested and certified for the target hazardous area. Look for appropriate listings/certifications (UL for NEC, CSA for CEC, IECEx, ATEX). Key cable characteristics include:
     • ​Robust Insulation/Jacket: Resists chemicals, moisture, abrasion, and temperature extremes.
     • ​Shielding: Critical for EMC performance and intrinsic safety applications (controlling capacitance/inductance).
     • ​Compatibility: Jacket material must be compatible with any gland seals or conduit seals used.
   • ​Connectors/Glands: Must have matching certification for the same hazardous area and be compatible with the cable type and the enclosure they enter. Explosionproof (flamepath), increased safety (Ex e), or cable glands certified for specific cable types are common.
   • ​Conduit & Fittings: If using conduit, ensure the conduit material (e.g., rigid metal), couplings, and explosionproof/sealing fittings are approved for the location.
3. ​Demand Assembly Certification: For the highest assurance and simplified compliance, source ​fully certified cable assemblies from reputable manufacturers. This means the entire assembly – cable, connectors, glands, terminations – has been tested and certified together as a system for the specified hazardous location. This removes ambiguity and liability from the installer.
4. ​Focus on Installation Quality: Even certified equipment fails if installed incorrectly. Follow:
   • ​Manufacturer Instructions: Adhere meticulously to the installation guidelines for every component and the certified assembly.
   • ​Proper Sealing: Ensure seals (conduit, cable glands) are correctly installed using the right tools and materials (e.g., compound, sealing washers) to maintain the integrity of the protection method (e.g., flamepath, ingress protection).
   • ​Grounding/Bonding: Essential for safety and EMC performance, especially for shielded cables. Follow applicable codes and assembly specifications.
   • ​Strain Relief: Prevent cable pullout from damaging terminations or breaking sealing integrity.
5. ​Documentation is Key: Maintain records of:
   • Certificates for all components and final assemblies.
   • Installation instructions followed.
   • Hazardous area classification for the location.

In Summary: Your Safety Checklist

• ​Know your zone: What specific hazardous area classification applies?
• ​Demand certification: Use components (cables, connectors, glands) and ideally full assemblies certified for that specific hazardous location by a recognized body (IECEx, UL, CSA, ATEX).
• ​Install meticulously: Seals, grounding, strain relief, and following instructions are non-negotiable.
• ​Document everything: Keep certifications and installation records.

Conclusion

Safety in hazardous areas is paramount. Choosing cable assemblies designed, certified, and installed according to rigorous international (IECEx) or North American (NEC/CEC) standards is not optional – it’s essential. By understanding these standards, prioritizing certified solutions (especially fully certified assemblies), and ensuring quality installation, you significantly mitigate the risk of ignition and create a safer working environment. Always consult with hazardous area experts and certification bodies when in doubt.