Wire & Cable Compounds

OTECH develops, designs, and custom manufactures high-quality specialty PVC compounds and thermoplastic elastomers for the electrical wire and cable industry.

138 Thermo Plastic Elastomer. The Marquis of OTECH Compounds

The 138 is a long-standing OTECH proprietary technology that has been re-imagined into the emerging wind-power cable application.

The wind turbine industry showcases the performance characteristics better than any other application of The 138.

Electricity generated by wind turbines travels down large cables from the nacelle, though the tower, and into an underground cable providing a consistent flow of renewable energy during high and low temperatures, all thanks to OTECH’s innovative team of compounders.

Through formulary excellence OTECH has been able to stretch the performance temperature range from 105 °C to -40 °C to cold impact.

Today there are several variations of The 138 tailored to meet specific extreme harsh environments and high performance customer needs.

OTECH continues to dominate the wire market in areas where wire manufacturers need one compound which can reach extreme opposite properties, and still be affordable.

OTECH has a wide product line of, and custom development capability for, flame and smoke suppressed wire & cable compounds to meet the entire flame-retardant hierarchy of wire constructions. OTECH’s compounds satisfy all the requirements across the entire hierarchy of wire constructions, from vw1 to tray cable to plenum compounds.

-40 °C Cold Impact

-55°C Brittle Point

FDA

Oil RES I, II

FT-4 IEEE Flame Rated

Sunlight Resistance

Proposition 65 Compliance

Wire and Cable Compounds: Enhancing Performance and Safety in Electrical Applications

What Are Wire and Cable Compounds?

Wire and cable compounds are mostly used as jacketing and insulation on finished wire and cable. Insulation compounds have high resistance to electrical flow to prevent electric shock when handling live wire and cable. Jacketing compounds are used to hold the constructed cable together. They often have resistance to chemicals and ultraviolet radiation.

Importance of Specialized Compounds in Electrical Applications

Specialized compounds allow wire and cable to perform in the environment that it is designed for. The compounds must meet the electrical, thermal, chemical, UV and durability requirements to last where they will be used.

Evolution of Wire and Cable Insulation Materials

In the 1880’s a natural latex was used to insulate cables. If the insulation was not kept wet, it would fail to insulate the conductors. In the 1890’s, impregnated paper was used as insulation on cables that carried voltages as high as 10kV.By the 1930s, PVC was being experimented with in Germany to insulate cables. By the end of WWII, there were several varieties of synthetic rubbers available for this purpose. In the 1950’s PVC was commercially viable and replaced rubber cables in many areas, especially domestic wiring. In the 1980’s, PVC alternatives such as low smoke zero halogen compounds were developed due to a number of public fires demonstrated the dangers of toxic gasses that were released during the combustion of the PVC.

Common Challenges in Material Selection

A balance must be maintained between thermal resistance, electrical insulation, mechanical strength, chemical and UV resistance while also considering cost. Compliance with regulatory agencies such as Underwriters Laboratories or the Canadian Standards Association must also be considered if required for the application.

Types of Wire and Cable Compounds

PVC (Polyvinyl Chloride) Compounds and Their Applications

PVC compound is commonly used in domestic wiring applications in homes. PVC is also used for insulation for low and medium voltage applications. It can be used in control and instrumentation systems, mining and ship wiring. It is also widely used in the telecommunication industry to protect the conductors from moisture, heat and other environmental factors. PVC compounds are also used for automotive wiring, consumer electronics and marine applications where resistance to salt water is crucial. PVC is generally the most economic option for (a wide variety of ) wire and cable (applications).

XLPE (Cross-Linked Polyethylene) vs. Thermoset Rubber

XLPE offers resistance to environmental stress cracking, ozone, solvents and soldering. They have high thermal stability and mechanical strength making it suitable for long distance transmission and applications in harsh environments. XLPE is generally less flexible than thermoset rubber and may have higher dielectric losses. 

Thermoset rubbers have greater flexibility and resilience which makes them suitable for dynamic environments. They have excellent low temperature resistance and chemical resistance. They also feature good mechanical impact resistance and resistance to moisture. They may not be as mechanically strong as XLPE compounds.

 

Thermoplastic Elastomers (TPE) and Specialty Polymers

TPE compounds combine the properties of plastic and rubber offering a balance of flexibility, durability and performance in various environments. They offer a wide range of temperature performance able to withstand environments from -35C to 100C. TPEs (specifically TPU) provide excellent abrasion resistance. There are halogen free options available using TPE compounds.

Halogen-Free and Low-Smoke (LSZH) Compounds

Halogenated compounds, such as PVC, can off-gas carcinogenic materials such as dioxins and phthalates when exposed to heat and flame. The smoke from halogenated materials is also corrosive. This can cause damage to equipment in the area of a fire. This is also a risk to be considered when attempting to recycle halogenated materials. Halogen free compounds began to be developed in the 1990’s to eliminate these risks. Halogen free compounds use polymers such as silicone rubber, polyurethane, polyethylene, polypropylene and EPDM.

Material Selection and Formulation

Factors Affecting Compound Selection for Different Applications

When selecting a compound for an application several factors need to be considered. Will the finished cable be exposed to high or low temperatures in the environment where it will be installed? Will it be installed in a dynamic environment where it is part of a system of moving parts? Will the cable be exposed to sunlight? Will the cable be exposed to chemicals such as oils and lubricants? What voltage load will the cable be expected to carry? What are the regulatory requirements for the cable?

Role of Plasticizers, Flame Retardants, and Stabilizers

Plasticizer plays a major role in determining the performance characteristics of the compound. The quantity of plasticizer used determines the hardness of the compound. The type of plasticizer selected will determine the compound’s resistance to heat, cold, and chemical attack. Certain plasticizers are disallowed by certain regulatory agencies and must not be selected for compounds that need to meet these regulatory requirements.

Flame retardants prevent or slow down the spread of fire by inhibiting ignition and flame propagation. This extends the time available for safe evacuation during a fire. They are generally produced from heavy metals. Some examples are, antimony trioxide, aluminium hydroxide, magnesium hydroxide and tetrabromophthalate based plasticizers. As with plasticizers, care must be taken when selecting a flame retardant as some are disallowed by various regulatory agencies.

Stabilizers are crucial, especially in PVC compounds. They prevent polymer degradation caused by exposure to heat during processing and in end use applications. Stabilizers also protect against discoloration caused by exposure to heat. A few examples of heat stabilizers include calcium zinc and barium zinc. Lead stabilizers are no longer used due to environmental and health concerns. UV stabilizers are used to protect polymers from degradation caused by exposure to ultraviolet radiation. Compounds that aren’t protected against UV radiation can become brittle causing a loss of mechanical properties. Discoloration can also occur.

Conductivity, Dielectric Strength, and Mechanical Properties

Conductive wire and cable jacketing and insulation compound is formulated using a conductive carbon black filler. These are used in cables where anti-static properties are needed to mitigate the risk of electronic components being destroyed by overvoltage due to electrostatic charging. These compounds are also used to shield cables from electromagnetic interference (EMI). A cable in proximity to a strong electromagnetic field gets exposed to unwanted currents and experiences surges in voltage resulting in electrical “noise”.
 
Dielectric strength refers to the maximum voltage an insulating material can withstand before dielectric breakdown occurs. This value is manipulated in the compound through use of fillers with a plated structure such as calcined clay. Increasing the level of this filler increases the dielectric strength of the insulating compound.


The mechanical properties of wire and cable include: Tensile strength and elongation. These refer to the maximum force a wire or cable can withstand before breaking under tension and how far they are capable of stretching before breaking. These properties are primarily influenced by material hardness and the molecular weight of the resin that is used. Another important property is a cable’s ability to remain flexible in low temperature environments. Plasticizer selection is crucial to pass the cold bend test that is associated with this property.  

Performance and Compliance Standards

Understanding Flame Retardancy and Fire Safety Regulations

Wire and cable fire safety regulations are crucial for minimizing fire risks. They primarily deal with the insulation and jacketing materials that are used on wire and cable. These materials must be flame retardant and produce a minimal amount of smoke in a fire. Specific tests are carried out by UL to determine that cables meet regulations. A few of the more common tests are the vertical wire flame test (VW-1) and the vertical tray flame test (FT-4), UL 1666 Riser and Ul’s 910 Steiner Tunnel plenum flame test.

Temperature Resistance and Thermal Stability

UL will carry out accelerated oven aging tests to ensure that a compound complies with heat resistance requirements. OTECH offers compounds that range from 60-105C in temperature rating. Thermal stability and plasticizer selection play important roles in passing this accelerated aging test. UL also carries out cold bend testing which involves conditioning a cable at a specified low temperature (-40C is one example) for a specified time. The cable is then wrapped around a mandrel to ensure that the jacketing and insulation will not crack if installed in a cold location. Cold impact testing can also be performed to ensure that a cable will not crack when a specified amount of weight is dropped on it after being conditioned in a low temperature freezer.

UV, Chemical, and Weather Resistance in Harsh Environments

In addition to the cold bend and cold impact testing mentioned above, UL also tests for UV resistance. Cable specimens are conditioned in a xenon arc UV chamber for 300 or 720 hours depending on the rating of the cable. After conditioning, tensile strength and elongation are tested. The conditioned samples must have 80% of the values of unconditioned control samples. A similar test is performed by conditioning samples in IRM 902 oil at elevated temperatures. Again, tensile strength and elongation data is compared to that of unconditioned samples.

Testing Protocols to Ensure Quality and Compliance

NSF and CSA conduct annual audits where production records are examined and samples are submitted by OTECH for compliance testing in their laboratories. 


UL conducts quarterly audits where OTECH submits samples for elemental analysis which is compared to a standard that UL has on file to ensure that the formulation contains all of the proper additives at the correct addition levels.

 

Manufacturing and Processing Considerations

Extrusion and Molding Techniques for Wire and Cable

Wire and cable extrusion is the process of extruding coating over a conductor or conductors. The process involves conveying pelletized compound through a heated screw and barrel. At the end of the barrel the melted material is extruded through a die onto the conductor. Different dies are used depending on the desired dimensions of the wire or cable. The cable then runs through a bath of water which cools the material. After this, the cable is printed with the necessary markings. Finally it is wound onto a reel. 

Electrical components are injection molded. This process involves feeding pelletized compound into a hopper where they are fed into the barrel of the injection molding machine. The molten compound is then pushed to the front of the screw and is ready for injection. The mold is closed and the molten material is forced through a nozzle into a mold cavity. Pressure is used during injection to make sure the mold cavity is completely filled. After cooling in the mold, the finished part is then ejected. 

Challenges in Processing and How to Overcome Them

The biggest key to processing successfully is choosing the proper process parameters. The design of the screw used in the extruder must be appropriate for the polymer you intend to process. The correct screen pack configuration must be selected. Too much screening can cause shear to build up in the screw which will cause the material to burn. Too little screening can allow contaminants to pass through and cause surface defects on the jacket. It is also critical to select the proper temperature parameters. Too high a temperature will result in burnt material and voids in the finished jacket from gasses getting trapped in the extruder. These voids will negatively impact the mechanical properties of the finished cable. Too low a temperature will result in a finished surface which is not smooth.

OTECH is able to provide customers with processing recommendations for every compound we produce. We are also available for onsite technical service visits to assist with processing the material.

Waste Reduction and Sustainable Manufacturing Practices

Copper and aluminium are highly recyclable. Thermoplastic waste is able to be ground up and re-introduced into the product stream at a low percentage. Recycling rates can be greatly improved by ensuring that scrap types are properly sorted.

Innovations in Coating and Jacketing Technologies

A continuing trend in the wire and cable industry is the shift to low smoke, zero halogen materials. Growing regulatory compliance standards are pushing industries to adopt LSZH compounds that ensure safety and environmental sustainability.

Best Practices for Ensuring Product Consistency

Specimens must be cut periodically from the cable for the lab to test. These tests include measurement with calipers to ensure that the dimensions of the cable are within tolerances. Tensile strength and elongation need to be measured to ensure the cable will meet UL standards. VW-1 testing is relatively uncomplicated and may be performed to ensure cables meet UL flame specifications. Once process conditions have been established, they must be followed to ensure consistency.

Future Trends in Wire and Cable Compounds

Advances in Low-Smoke, Halogen-Free Compounds

Researchers are working to enhance the flexibility, mechanical strength and temperature resistance of LSZH compounds to make them suitable for a wider range of applications. Innovations in polymer chemistry and additive technologies are driving the development of new LSZH compounds with superior performance characteristics.

The Shift Toward Recyclable and Bio-Based Materials

There are an increasing amount of bio based resins and plasticizers available for use in the production of wire and cable compounds. Some examples are: Polyethylene produced from sugar cane ethanol, plasticizers derived from natural oils such as soybean oil. Other available feedstocks include: sunflower oil, canola oil, corn and algae.

Smart and Conductive Polymers for Next-Gen Cables

OTECH produces a variety of conductive PVC compounds suitable for use in the wire and cable industry. The surface resistivity of these compounds can range from 10^1 – 10^7 making them ideal for semi-conductive or ESD applications.

Industry 4.0 and Automation in Wire and Cable Production

Industry 4.0 has not been widely embraced by the wire and cable industry outside of Germany. It is more challenging to integrate Industry 4.0 in a linear manufacturing process where customization is a vital aspect of the business. Manufacturers are reluctant to make the large up front investment when they feel satisfied with their profitability they achieve using Industry 2.5. It can be difficult to accept the expense of using robotics when one human can service five machines where a robot can only service one. These short-sighted philosophies may not be a viable approach as the market develops.

How OTECH is Leading the Way in Material Innovation

With the restrictions on exportation of Antimony to the United States by China, alternative flame retardant solutions must be found. OTECH has partnered with our suppliers to develop flame retardant, antimony free compounds for use in the wire and cable industry.

 

Frequently Asked Questions

Cable Compound Formulation and Selection

The formulation of cable compounds requires careful consideration of multiple technical factors that directly impact performance and safety. The process begins with understanding the fundamental requirements of the specific application, whether for construction or telecommunications use.

Key construction cable considerations:

  • Wire gauge specifications: American Wire Gauge (AWG) standard, ranging from 4/0 (largest) to 40 (smallest), determines current-carrying capacity
  • Insulation material selection: Materials like XLPE (cross-linked polyethylene) rated up to 90°C or PVC rated to 75°C
  • Conductor material type: Usually copper (100% IACS conductivity) or aluminum (61% IACS conductivity)
  • Voltage rating requirements: Low voltage (300-600V), medium voltage (5-35kV), or high voltage (>35kV)
  • Shield requirements: Options including tape shield (100% coverage) or braid shield (85-95% coverage)

For telecommunications applications, critical specifications include:

  • Number of wire pairs: Ranging from single pair to 1,800 pairs per cable
  • UL style requirements: Style numbers (e.g., UL 1015 for machine tool wire, UL 1007 for appliance wiring)
  • Category type classification: Cat5e (100MHz), Cat6 (250MHz), Cat6a (500MHz), Cat7 (600MHz), Cat8 (2000MHz)
  • Flame retardancy standards: NFPA 262 for plenum, UL 1666 for riser applications

When developing high-performance compounds, several critical parameters must be evaluated:

Environmental Resistance:

  • Chemical exposure tolerance: Tested per ASTM D543 for specific chemical resistance
  • UV resistance capabilities: Measured in hours of UV exposure per ASTM G154
  • Operating temperature range: Typically -40°C to +75°C for PVC, up to 90°C for XLPE

Safety Requirements:

  • Flame retardance specifications: UL 94 V-0/V-1/V-2, limited oxygen index (LOI) typically >21%
  • Smoke emission standards: ASTM E662 for smoke density, maximum 450 at 4 minutes

Physical Properties:

  • Tensile strength: ASTM D638, typically 2000-3000 psi for jacket compounds
  • Elongation characteristics: ASTM D638, usually 200-400% for jacket materials
  • Abrasion resistance: Taber test per ASTM D4060, measured in cycles to failure

Selecting the appropriate cable compound requires a comprehensive evaluation of both application requirements and environmental conditions.

Insulation Considerations:

  • Voltage rating: Breakdown voltage >20kV/mm for medium voltage applications
  • Temperature rating: Heat deformation <50% at rated temperature per UL 2556
  • Volume resistivity: Typically >1014 ohm-cm for electrical grade compounds
  • Dielectric strength: Minimum 500 V/mil per ASTM D149

Jacket Requirements:

  • Environmental resistance: Weather resistance per ASTM G154 >1000 hours
  • Chemical resistance: Oil resistance per UL Oil 1/Oil 2 immersion tests
  • Impact strength: Typically >8 ft-lbs/inch at room temperature
  • Cold bend performance: No cracking at -20°C per UL 1581

Understanding regulatory compliance is essential for wire and cable applications. The primary regulatory bodies overseeing these materials are Underwriters Laboratories (UL) and CSA (Canadian Standards Association).

Critical safety classifications include:

  • UL 94 HB certification: Horizontal burn test, burning rate <3 inches/minute for thickness >0.120 inches
  • V-0 rating: Self-extinguishes within 10 seconds, no burning drips, afterglow <30 seconds
  • V-2 rating: Self-extinguishes within 30 seconds, burning drips allowed
  • VW-1 specification: Vertical flame test, 5 x 15-second flame applications with no burning drips
  • E84 standard compliance: Measures flame spread index (<25) and smoke developed index (<50)

The relationship between regulatory standards and material selection is direct and significant.

Impact considerations:

  • Raw material selection: Flame retardants (antimony trioxide loading 3-5%, brominated compounds 12-15%)
  • Heat stabilizer requirements: Typically 2-4 phr calcium/zinc-based for PVC
  • Processing aids: Internal/external lubricants at 0.5-2.0 phr
  • Filler loading: Calcium carbonate typically 20-40 phr for cost/performance balance
  • Impact modifier content: 5-10 phr for improved low-temperature performance

Performance evaluation must encompass both electrical and physical characteristics:

Electrical Performance Metrics:

  • Dielectric constant: Typically 2.3-3.5 at 100 Hz
  • Dissipation factor: <0.01 at 100 Hz for quality insulation
  • Volume resistivity: >1014 ohm-cm at room temperature
  • Insulation resistance: Minimum 100 megohms per 1000 ft

Durability Assessment:

  • Chemical resistance: Per ASTM D543 for specific reagents
  • Abrasion resistance: <0.1g loss per 1000 cycles on Taber abraser
  • Heat aging: 7 days at rated temperature per UL 2556
  • Water absorption: <0.5% after 24-hour immersion at 23°C <0.5% after 24-hour immersion at 23°C

Professional expertise becomes particularly valuable in several specific technical scenarios:

Material Performance Requirements:

  • Complex electrical specifications: When volume resistivity exceeds 1016 ohm-cm
  • Dual certification needs: UL/CSA harmonized specifications
  • Extreme temperature applications: Performance beyond -50°C to +105°C
  • Special mechanical properties: Impact strength >10 ft-lbs/inch

Environmental Challenges:

  • Chemical exposure: Multiple reagent resistance per ASTM D543
  • UV stability requirements: >2000 hours exposure per ASTM G154
  • Thermal aging: >10,000 hours at rated temperature
  • Environmental stress cracking: >500 hours per ASTM D1693

Specialized Testing Requirements:

  • Smoke density testing: ASTM E662 (<450 at 4 minutes)
  • Toxicity testing: BSS 7239 or SMP 800-C
  • Limited oxygen index: ASTM D2863 (>28%)
  • Heat release testing: ASTM E1354 (<100 kW/m2)

Expert consultation provides specific guidance on:

Formulation Optimization:

  • Base resin selection: Molecular weight optimization (K-value 57-70 for PVC)
  • Stabilizer packages: Synergistic combinations for long-term stability
  • Plasticizer systems: Non-migrating types (polymeric vs. monomeric)
  • Flame retardant loading: Optimized for performance/cost (typical ranges):
    • Antimony trioxide: 3-5 phr
    • Aluminum trihydrate: 30-60 phr
    • Brominated compounds: 12-15 phr

Processing Parameters:

  • Extrusion temperature profiles: Typically 160-200°C for PVC
  • Screw design optimization: L/D ratio 24:1 to 32:1
  • Die design considerations: Draw down ratio 1.1-1.3
  • Line speed optimization: 100-300 ft/min depending on construction

Regulatory Compliance:

  • UL yellow card requirements:
    • RTI (Relative Temperature Index) ratings
    • Flame ratings
    • Electrical properties
  • RoHS compliance: <1000 ppm restricted substances
  • REACH registration requirements
  • California Proposition 65 compliance

Quality Control Metrics:

  • In-process testing requirements:
    • Melt flow rate: ±10% of target
    • Specific gravity: ±0.02 of target
    • Shore hardness: ±3 points of target
    • Color matching: ΔE <1.0

Final Product Validation:

  • Spark testing: 2.5-3x rated voltage
  • Conductor resistance: Within ±2% of nominal
  • Insulation resistance: >100 megohms per 1000 ft
  • Cold bend performance: No cracks at minimum temperature
  • Heat deformation: <50% at maximum temperature
  • Tensile properties:
    • Strength: ±10% of specified value
    • Elongation: ±15% of specified value

Long-term Reliability Assessments:

  • Accelerated aging protocols:
    • Thermal aging: 7-180 days at elevated temperature
    • UV exposure: 1000-2000 hours
    • Chemical immersion: 7-30 days
  • Performance retention requirements:
    • Tensile strength: >75% retention
    • Elongation: >50% retention
    • Impact strength: >70% retention

Cost-Performance Optimization:

  • Raw material selection strategies:
    • Premium vs. standard grades
    • Recycled content incorporation
    • Alternative flame retardant systems
  • Processing efficiency improvements:
    • Line speed optimization
    • Scrap rate reduction
    • Energy consumption reduction
  • Quality control optimization:
    • Statistical process control implementation
    • Automated inspection systems
    • Preventive maintenance scheduling

This comprehensive technical guidance ensures optimal material selection, processing parameters, and end-product performance while maintaining regulatory compliance and cost effectiveness.

CSA

CSA Rated

NSF

ANSI 51

NSF

ANSI 61

NAMSA

Class VI Compounds

UL Listing

Plenum Cable Compounds

UL

QMTT2 Recognized Materials

UL

Plastics Component V-0, V-2 Rated

UL

Plastics Component V-0, V-2 Rated. Canada

UL

TPE - 720 Mr. Sunlight Resistant Jacket

4744 E. Oaknoll Road
Rolling Prairie, IN 46371

Phone: 219-778-8001
Fax: 219-778-8007

Speak with an Expert