In environments where explosive atmospheres are a constant concern—such as oil refineries, gas plants, chemical manufacturing facilities, and grain silos—electrical components must be carefully selected to ensure they do not become an ignition source. One often overlooked component is the humble cable. While it may seem like a minor detail, using the wrong type of cable can compromise an entire intrinsically safe system.
Intrinsically safe cables are specifically designed to limit the energy—both electrical and thermal—transmitted through them, making them incapable of igniting a hazardous atmosphere. In this article, we will break down the key considerations for selecting the right intrinsically safe cable, explain the relevant certifications like ATEX, and recommend compliant product options available from Intrinsically Safe Store.
What Is an Intrinsically Safe Cable?
An intrinsically safe cable is a specialized electrical cable engineered to ensure that, even in the presence of flammable gases, vapors, or dust, it cannot produce a spark or heat level sufficient to ignite an explosion. These cables are typically part of a broader intrinsically safe system, which includes barriers, certified devices, and safe wiring methods.
Characteristics of Intrinsically Safe Cables
Energy Limitation: The cable’s capacitance and inductance are strictly controlled to prevent the storage or transmission of excess energy.
Distinctive Color Coding: Most intrinsically safe cables are blue, a widely recognized industry standard to indicate intrinsic safety.
High-Quality Insulation: Often features polyurethane or other rugged materials to withstand industrial environments.
Shielding: Many are shielded to prevent electromagnetic interference (EMI), which could affect sensitive instrumentation.
Low Capacitance and Inductance: Critical for ensuring compliance with safety calculations outlined in ATEX and IECEx guidelines.
Understanding ATEX and Related Certifications
What Is ATEX?
ATEX stands for “Atmosphères Explosibles” and refers to the European Union directives that regulate equipment used in explosive atmospheres. Cables used in ATEX zones must conform to two directives:
ATEX 2014/34/EU (formerly ATEX 95): Applies to electrical and non-electrical equipment used in potentially explosive areas.
ATEX 1999/92/EC (ATEX 137): Focuses on worker safety and the proper use of certified equipment.
Other Relevant Certifications
IECEx: An international certification for equipment used in explosive atmospheres.
UL 60079-11 / UL 913: U.S. certifications for intrinsically safe systems and components.
CSA: Canadian standard aligned with North American explosion protection.
To be classified as intrinsically safe, a cable must conform to these standards and be properly matched with other components of the intrinsically safe loop.
Key Factors to Consider When Choosing Intrinsically Safe Cables
1. Zone Classification
The first step in choosing the right cable is identifying the ATEX zone where it will be used. These zones are categorized based on the frequency and duration of the presence of explosive gases or dust.
Zone 0: Continuous presence of hazardous material (highest risk).
Zone 1: Likely presence during normal operations.
Zone 2: Unlikely presence and only for short durations.
The higher the risk (Zone 0 or 1), the stricter the cable requirements.
2. System Capacitance and Inductance
Every intrinsically safe system has limits for how much energy its components can store. Cables must have:
Low capacitance (C): To prevent energy storage.
Low inductance (L): To reduce the risk of voltage spikes or arcs.
The cable’s length and properties must be considered when calculating the total system safety per the entity concept.
3. Cable Construction
Opt for cables with:
Robust Outer Sheath: Preferably polyurethane for high resistance to abrasion and chemicals.
Shielding: Braided or foil shielding to eliminate EMI in communication cables.
Color Coding: Blue insulation to signify intrinsic safety.
4. Environmental Conditions
Assess the operating environment. Will the cable be exposed to:
Extreme temperatures?
Chemical vapors or liquids?
Mechanical stress?
Water or moisture ingress?
Cables used in outdoor or corrosive environments must be rated for these conditions.
5. Cable Type and Application
Control Cables: For signal and data transmission in control loops.
Power-Limited Tray Cable (PLTC): For fixed installations, often armored for protection.
Multiconductor Cables: For connecting multiple devices in intrinsically safe zones.
Top Intrinsically Safe Cable Products to Consider
Based on current availability at Intrinsically Safe Store, the following cable products are recommended for use in ATEX-rated installations:
ÖLFLEX® EB
Blue polyurethane jacket
Designed specifically for use in hazardous environments
Flame-retardant and oil-resistant
Ideal for control and signal cables in ATEX zones
ÖLFLEX® EB CY
Shielded version of the ÖLFLEX EB
Braided copper shield provides protection from EMI
Low capacitance for increased safety in signal circuits
Suitable for instrumentation and data transmission
OZ-BL Blue Control Cable
Flexible control cable for intrinsically safe applications
Halogen-free and flame-retardant
Suitable for measuring and control circuits in explosive atmospheres
Each of these options is constructed to meet international standards for intrinsic safety, making them suitable for integration into ATEX- or IECEx-certified systems.
Comparison Table: Intrinsically Safe Cables
| Product Name | Sheathing | Shielding | Ideal Application | Certification |
|---|---|---|---|---|
| MDC-4FPX-ZZ Cable – 4-Pin Female Plug | Polyurethane | Yes | Control systems in hazardous areas | ATEX Certified |
| MDC-2FP-ZZ 2-Pin M12 Cable (20 AWG) | Polyurethane | Yes | Signal transmission in explosive atmospheres | ATEX Certified |
| GameChanger Hazardous Location Cable | Polyethylene | No | Data communication in industrial environments | ATEX Certified |
FAQs
What makes a cable “intrinsically safe”?
A cable is intrinsically safe when it is designed to limit the energy passing through it, preventing ignition of flammable gases or dust. This is achieved through specific construction properties like low capacitance, shielding, and flame-retardant sheathing.
Can I use a regular cable in an ATEX Zone 1 or 0?
No. Cables used in ATEX zones must meet strict standards to prevent ignition risks. Using a regular, non-certified cable in these environments is both dangerous and non-compliant.
Are intrinsically safe cables always blue?
While not mandatory, blue is the standard industry color to indicate intrinsic safety, especially for quick identification during installation and inspection.
Do intrinsically safe cables have to be part of a complete certified system?
Yes. Cables must be used in conjunction with other certified intrinsically safe components such as barriers, isolators, and devices. Certification is only valid when the system is assessed as a whole.
How do I calculate the safe length for an intrinsically safe cable?
Safe lengths are determined by assessing the total loop capacitance and inductance. These values must fall below the maximum allowed by the system’s entity parameters (defined by the device and barrier).
Best Choice by Industry Use Case
| Industry | Recommended Cable | Justification |
|---|---|---|
| Oil & Gas | MDC-4FPX-ZZ Cable – 4-Pin Female Plug | High resistance to hydrocarbons and mechanical stress |
| Chemical Manufacturing | MDC-2FP-ZZ 2-Pin M12 Cable (20 AWG) | Excellent chemical resistance and flexibility |
| Mining | GameChanger Hazardous Location Cable | Durable construction suitable for underground environments |
| Food & Pharmaceutical Processing | MDC-4FPX-ZZ Cable – 4-Pin Female Plug | Complies with hygiene standards and easy to clean |
| Utilities & Power Plants | MDC-2FP-ZZ 2-Pin M12 Cable (20 AWG) | Reliable performance in high-temperature areas |
Conclusion
Choosing the right intrinsically safe cable for your ATEX equipment is not just a matter of preference—it’s a regulatory and safety requirement. From understanding your zone classification and installation environment to evaluating certifications and cable specifications, every detail plays a crucial role in maintaining operational safety.
Cables like the ÖLFLEX® EB, EB CY, and OZ-BL provide rugged, compliant solutions for a variety of industrial settings. When integrated correctly with ATEX-certified systems, these cables help ensure uninterrupted communication, control, and compliance in even the most hazardous conditions.
