By Eileen Harvey
In industries where heavy machinery, high electrical loads and combustible substances are the norm, fire safety is essential. Industrial Ethernet cables, the backbone of modern automation networks, must often endure extreme heat, mechanical stress and potential fire hazards. But are they flame-retardant?
Many industrial Ethernet cables are engineered to be flame-retardant. But not all of them are, and the degree of flame resistance varies depending on materials, construction and certification.
What Does Flame-Retardant Mean for Ethernet Cables?
A flame-retardant cable is designed to resist burning and stop the spread of fire along the cable. In a fire event, a flame-retardant industrial Ethernet cable will slow down burning and self-extinguish over a certain distance. In advanced designs, it will emit minimal toxic gases and smoke.
Why is This Crucial?
Let’s look at several reasons. First, industrial environments (factories, oil and gas, refineries, food processing plants) harbor ignition sources, chemicals and extensive wiring. Second, a fire spreading along cable trays or bundles can cripple operations and put lives at risk. And third, strict building codes and insurance standards now require flame-retardant (or higher) ratings for most industrial cabling installations.
A non-flame-retardant cable can act like a fuse—allowing flames to spread rapidly along trays and conduits, endangering workers and destroying equipment.
Flame-retardant Ethernet cables are engineered to resist ignition, self-extinguish after exposure to flame and limit fire spread. This not only protects personnel but also prevents catastrophic downtime for mission-critical industrial networks.
Flame-Retardant vs. Fire-Resistant vs. Low-Smoke Zero Halogen
It’s easy to confuse these terms. When a cable is flame-retardant, it is designed to resist burning and prevent flames from spreading. When a cable is fire-resistant, it is designed to continue functioning during fire exposure for a set time. When a cable is low-smoke zero halogen (LSZH) it produces minimal toxic smoke when burned and thus is useful in enclosed spaces.
Industrial Ethernet cables are often flame-retardant by design, but not necessarily fire-resistant unless built for specialized applications.
Key Flame-Retardant Standards for Industrial Ethernet Cables
Several standardized testing methods are used to determine how industrial Ethernet cables perform under flame conditions. One of the most widely recognized is UL 1581 VW-1 Vertical Wire Flame Test, which simulates a cable burning in a vertical position to assess whether the flames will self-extinguish. Cables that pass the VW-1 test demonstrate the ability to limit upward flame spread, making them safer in applications where fire resistance is critical.
Another important benchmark is IEC 60332, which is divided into multiple parts. Part 1 is a single-cable test designed to evaluate flame resistance on an individual cable. Part 3 is a cable bunch test that measures flame spread when multiple cables are bundled together, reflecting real-world installation conditions.
The UL 1685 Vertical Tray Flame Test is also significant, as it evaluates flame spread in bundled cables mounted within trays. This test closely mirrors conditions in many industrial environments where cable trays are commonly used to organize and support large numbers of cables.
Finally, NFPA 70, also known as the National Electrical Code (NEC), specifies fire safety requirements for electrical installations. This standard includes guidance on plenum and riser ratings, which are essential for determining whether cables can be installed in air-handling spaces or between building floors while maintaining compliance with fire safety codes.
Flame-Retardant Standards and Fire Ratings
In the United States, cable fire ratings are primarily defined by the National Electrical Code (NEC) and Underwriters Laboratories (UL). Three principal classifications are used for communications cables: CM, CMR and CMP.
CM, or Communications-rated cables, are the most widely used flame-retardant type. They must self-extinguish with less than five meters of flame spread under the UL 1581 test.
CMR, or Riser-rated cables, are designed for use in vertical shafts and riser spaces. They are tested under UL 1666, which requires a higher ignition point and enhanced flame retardancy compared to CM.
CMP, or Plenum-rated cables, provide the highest level of flame resistance. These cables use halogen-free fluoropolymer jackets that emit very low smoke when exposed to fire. They are tested under UL 910 and are specifically designed for air-handling spaces, such as plenums.
If a cable does not carry a CM, CMR or CMP rating—or an international equivalent—it likely lacks flame-retardant properties and may not be safe or legal for industrial use.
Globally, other standards define flame performance and safety requirements. IEC 60332, Parts 1 and 3, sets widely referenced tests for flame propagation on both individual cables and bundles. EN 50200 and EN 50289-4-16 go further by testing circuit integrity, ensuring that cables can continue transmitting data during a fire. In the European Union, the Construction Products Regulation (CPR) classifies cables from Aca, meaning non-flammable, to Fca, meaning highly flammable. Within this system, flame-retardant performance is indicated by classes such as B1ca, B2ca, and Cca, which specify varying levels of safety for building installations.
The choice of jacket material also plays a major role in determining a cable’s flame performance and fire safety. PVC (polyvinyl chloride) is the most common option, offering flame-retardant properties by melting or charring instead of flaring rapidly.
LSZH (low smoke zero halogen), also known as LSOH, provides superior flame retardancy and produces minimal smoke and toxic gases, making it essential for high-safety environments such as tunnels, transportation systems and data centers.
PUR (polyurethane) is frequently used in flexible or robotic cables and can be formulated to include flame-retardant properties.
Finally, fluoropolymers such as FEP and PTFE are used in CMP-rated cables. These materials have the highest ignition and decomposition temperatures, are halogen-free and produce very low smoke, making them ideal for plenum applications where fire safety is most critical.
Do All Industrial Ethernet Cables Offer Flame Retardancy?
Most industrial Ethernet cables are flame-retardant—but not all are equal. Items to look for on a spec sheet are: CM, CMR or CMP (or international equivalents: IEC, EN, CPR); explicit mention of “flame retardant,” “LSZH,” or “fire behavior” in technical data; test methods (IEC 60332-1, IEC 60332-3, UL 1581, EN 50200); and halogen-free/low smoke declarations, important for escape safety.
If a cable lacks the above indications, avoid using it in any industrial, public or safety-affected environment.
Benefits of Flame-Retardant Industrial Ethernet Cables
Flame-retardant industrial Ethernet cables provide several critical advantages in both safety and performance. One of the most important benefits is their ability to prevent the spread of fire. By slowing or stopping the movement of flames along cable trays and runs, these cables reduce the risk of fire traveling quickly through industrial facilities.
Another key advantage is improved safety during evacuation. Flame-retardant designs produce less smoke and fewer toxic gases compared to standard cables, creating safer conditions for both escape and rescue operations. This not only protects lives but also gives emergency responders more time to act effectively.
Flame-retardant cables also help organizations maintain compliance with local building codes, insurance requirements and international safety standards. Using the correct fire-rated cables ensures that installations are legal, insurable and aligned with industry best practices.
Beyond safety, these cables protect data transmission and network uptime by maintaining connectivity for a longer period during fire conditions. This added resilience can be crucial in mission-critical operations where downtime translates directly into lost productivity, financial costs or safety risks.
Finally, flame-retardant Ethernet cables are particularly important in critical industries and environments such as oil and gas facilities, chemical processing plants, data centers, industrial automation systems and transport infrastructure. In these high-risk sectors, the combination of fire safety and reliable data transmission is essential to protect both people and assets.
How Are Flame-Retardant Properties Tested?
The flame-retardant properties of industrial Ethernet cables are evaluated through a series of rigorous standardized tests. In North America, several UL standards are commonly applied. UL 1581 is used for CM-rated cables and involves a vertical flame test that assesses performance for general, horizontal and limited riser applications. UL 1666 applies to CMR-rated riser cables and evaluates how well they resist flame spread in vertical shafts. The most demanding test is UL 910, which is used for CMP-rated plenum cables. This standard measures both flame resistance and smoke production, representing the highest fire-safety requirement in the region.
Internationally, IEC 60332 Parts 1 and 3 are widely referenced to determine flame propagation on single cables and flame spread across bundled cables, respectively. Another important benchmark is EN 50200, which tests circuit integrity by measuring whether a cable can remain operational for up to 120 minutes during fire exposure.
Some specialized products go even further in ensuring safety under fire conditions. For example, cables such as the ETHERLINE® FIRE series are designed to maintain insulation integrity for 120 minutes during a fire, making them especially suitable for safety-critical zones where continuous operation is essential.
Are All Flame-Retardant Cables Halogen-Free or Low-Smoke?
Not necessarily. PVC cables (CM/CMR) are flame-retardant but emit toxic gases and smoke when burned. LSZH cables combine flame retardancy with low smoke/halogen output (ideal for enclosed spaces and evacuation safety).
Pro Tip: For tunnels, trains, offshore and public buildings, always seek “LSZH” or “LSOH” along with flame resistance.
Frequently Asked Questions (FAQs)
Q1: Are all Ethernet cables flame-retardant?
A: No. Only those specifically marked with fire safety ratings (CM, CMR, CMP, IEC, EN, LSZH, etc.) provide flame-retardant or higher fire-safe properties.
Q2: Do I need flame-retardant cable outdoors?
A: Yes, if cables run near combustible materials, into buildings or through public/industrial spaces. Flame-retardancy is essential wherever fire risk can impact life or property.
Q3: What happens if I install non-flame-retardant cables?
A: You’re risking fire spread and toxic smoke, likely violating building/local codes, and possibly invalidating insurance.
Yes—industrial Ethernet cables can be and often are flame-retardant. The safest choice is always a cable with clear fire rating certification: CM/CMR/CMP (NEC/UL), IEC 60332-1/3, EN 50200 and/or CPR classes. For added safety, especially in mass-occupied, transport or escape-route settings, choose LSZH cables.
For industrial environments—whether it’s a steel mill, refinery, data center or smart factory—using a certified flame-retardant Ethernet cable dramatically reduces fire risk, ensures legal compliance and protects both production and people.
