Choosing Between Metal and Nylon Cable Glands for Your Wire Gland Needs

Effective cable management is critical in a wide range of industrial, commercial, and residential applications. Cable glands, sometimes referred to as wire glands, play a pivotal role in securing, sealing, and protecting the ends of electrical cables entering equipment or enclosures.

When selecting cable glands, one of the most important decisions is choosing between metal and plastic materials. Each offers distinct advantages and limitations, and understanding these will help you make an informed choice tailored to your project’s requirements.

What Are Cable Glands?

Cable glands are mechanical fittings that serve several vital functions:

Sealing and Protection: They maintain the integrity of enclosures against dust, moisture, and liquids, ensuring compliance with ingress protection (IP) ratings.

Grounding and Bonding: Certain designs (especially metal glands) provide an electrical path between cable armor and the enclosure, supporting system grounding requirements.

Strain Relief: By securing the cable’s outer sheath, they prevent undue stress on inner conductors, reducing the risk of cable damage or failure over time.

Cable Management: Cable glands help organize cable entries, minimise clutter, and improve overall aesthetics and safety in wiring systems.

Cable glands are available in a variety of thread standards (e.g., PG, NPT, Metric), sizes, and materials. The two most common materials are metal and plastic, each suited to different environments and performance demands.

Metal Cable Glands

Metal cable glands are typically made from brass (nickel-plated or unplated), stainless steel, or aluminum.

Their characteristics include:

Durability and Strength

Metal glands exhibit superior mechanical robustness. They resist crushing, impact, and tensile forces better than most plastics. This makes them ideal for heavy-duty and industrial environments where cables may be subject to frequent movement or mechanical stress.

High Temperature Resistance

Metals endure higher temperature ranges—often from –40°C up to +120°C or beyond—without significant degradation. This is essential for applications involving heat-generating equipment or exposure to sunlight in outdoor installations.

Superior Chemical Resistance

Stainless steel and nickel-plated brass resist corrosion from oils, solvents, and many industrial chemicals. Even in aggressive environments (e.g., offshore or chemical processing plants), metal glands maintain sealing performance and structural integrity.

EMC Shielding and Grounding

The electrical conductivity of metal glands enables them to provide electromagnetic compatibility (EMC) shielding and maintain continuous grounding paths for armored cables. This is crucial in sensitive electronic applications where interference must be minimized.

Certification and Compliance

Many metal cable glands meet stringent standards such as CE, RoHS,REACH,and UL, making them suitable for hazardous-area installations.

Limitations of Metal Glands

Cost

Metal glands are generally more expensive than plastic alternatives, both in material and manufacturing.

Weight

The added weight can be a consideration in weight-sensitive applications, such as mobile or aerospace installations.

Potential for Galvanic Corrosion

When used with dissimilar metals, there is a risk of galvanic corrosion unless proper measures (e.g., coatings or dielectric barriers) are taken.

Plastic Cable Glands

Plastic cable glands, often manufactured from polyamide (PA6/PA66) or polypropylene, offer a different balance of properties:

Lightweight and Cost-Effective

Plastic glands are significantly lighter than metal, reducing overall system weight. They are also less expensive, offering cost savings in large-scale installations or budget-conscious projects.

Electrical Insulation

Non-conductive by nature, plastic glands inherently insulate cables, eliminating concerns about accidental grounding or short circuits. In applications where electrical isolation is critical, plastic glands simplify design considerations.

Ease of Installation

Plastic glands often feature integrated sealing elements (e.g., elastomer inserts), requiring fewer components and reducing assembly time.

Corrosion-Free

Polyamide and similar plastics do not corrode, making them ideal for outdoor or marine environments where metal oxidation could be problematic. Their resistance to UV degradation (with proper additives) further enhances longevity in sunlight-exposed settings.

Wide Chemical Compatibility

While not as universally resistant as stainless steel, many engineering plastics withstand water, mild acids, bases, and a variety of cleaning agents. Some specialized formulations even resist fuels and oils.

Limitations of Nylon Glands

Lower Mechanical Strength

Although durable for general use, plastic glands can deform under high torque or impact, potentially compromising strain relief and sealing.

Temperature Constraints

Typical operating temperatures range from –20°C to +80°C for polyamide. Exposure beyond these limits can lead to softening, embrittlement, or seal failure.

Limited EMC Capabilities

As non-conductive components, plastic glands cannot provide electromagnetic shielding or grounding for armoured cables. Additional components are needed if EMC compliance is required.

Metal vs. Nylon Cable Glands: A Quick Comparison

Choosing the Right Option for High-Quality Cable Management

Selecting between metal and Nylon cable glands depends on several factors:

Environmental Conditions

Harsh, Industrial, or Outdoor: Metal glands are typically preferred in heavy-duty, high-temperature, or explosive atmospheres.

Less Demanding or Corrosive Environments: Plastic glands excel where chemical exposure is moderate, and weight or cost reduction is prioritized.

Mechanical Stress and Installation

Vibration and Movement: Metal glands better resist vibration, repeated flexing, and mechanical impact.

Quick Assembly: Plastic glands simplify installation with pre-fitted gaskets and lower torque requirements.

Electrical Requirements

EMC and Grounding: Metal glands provide shielding and grounding continuity—essential for sensitive instrumentation, power distribution, and armored cables.

Insulation Needs: Plastic glands offer inherent electrical isolation, beneficial in applications where grounding is not desired or must be avoided.

Regulatory and Safety Standards

Hazardous-Area Certification: Metal glands more readily meet ATEX, IECEx, and UL approvals for explosive environments.

Ingress Protection: Both materials can achieve high IP ratings (IP66, IP67, IP68), but metal variants often maintain rating integrity under temperature extremes.

Budget and Lifecycle Costs

Initial Cost vs. Longevity: While plastic glands save upfront cost, metal glands may offer lower total cost of ownership in demanding applications due to longer service life and reduced maintenance.

Aesthetic and Weight Considerations

In applications where appearance and minimal weight are critical (e.g., consumer electronics, solar panels), plastic glands provide a sleek, lightweight solution.

Conclusion

Metal cable glands offer unmatched mechanical strength, high temperature resistance, and electromagnetic compatibility, making them indispensable materials in industrial and hazardous environments.Nylon cable glands, on the other hand, offer a cost-effective, lightweight, and corrosion-free solution, ideal for less demanding environments and applications where electrical insulation is critical.

Whether you choose the rugged durability of metal or the versatility and economy of plastic, choosing the right cable gland ensures reliable cable management that protects equipment and personnel for years to come.