Types of Insulation Materials for Wire and Cable

What is Wire & Cable Insulation?

Insulation is a nonconductive material within a cable's construction. Insulation is also commonly called a dielectric when discussing radio frequency cables. The longevity and effectiveness of a wire depends on the type of insulation that is used. Dielectric and insulation materials preserve the material integrity of the wire by protecting the wire against environmental hazards and threats such as water, heat, chemicals, or physical damange. Wire insulation also resists electrical leakage, which prevents the wire’s electrical current from coming into contact with other wires and cables that are nearby.

What are the different types of Wire & Cable Insulation Materials?

There are many different kinds of wire and cable insulation materials available and performance varies depending on the use case. The three main insulation materials are Plastic, Rubber, and Fluoropolymer. The following is a list of wire and cable insulation materials with information on the typical uses, advantages, and disadvantages for each option. Insulation for both wires and cables are essentially the same. Wire insulation is insulating a single conductor; which is the definition of a wire. When referencing cables, cable insulation is referring to a cable made of multiple (wire) conductors. Cable insulation can refer to the insulation type surrounding each wire, or the insulation of the cable as a whole. The type of insulation and level of insulation required for your cable to perform at its best will depend on the specific applications use case.

Table of Contents

• Plastic Insulation
• Comparative Properties of Plastic Insulations
• Rubber Insulation
• Comparative Properties of Rubber Insulations
• Fluoropolymer Insulation
• Comparative Properties of Fluoropolymer Insulations

Plastic Insulation Types

Polyvinyl Chloride (PVC)

Polyvinyl Chlroride, or PVC, is a relatively inexpensive and easy-to-use wire & cable insulation material with the potential to be used in a diverse array applications. PVC insulation has a recommended operating temperature ranging from -55° Celsius to +105° Celsius and is resistant to flame, moisture, and abrasion. PVC wire insulation can also endure exposure to gasoline, ozone, acids, solvents, and other industrial chemicals. PVC is a common wire insulation material for medical and food-related purposes due to PVC material being odorless, tasteless, and nontoxic. Wire and cable with PVC insulation is suitable for both heavy- and thin-wall applications. However, PCV insulation displays high attenuation and capacitance loss, meaning there is some performance loss when compared to other insulation materials that could be used in an electrical system. PVC insulation also shows below-average flexibility when used in retractile cord applications, and should also not be used in environments where wire flexibilty and extended flex life would be required at low temperatures

Semi-Rigid PVC (SR-PVC)

Semi-Rigid PVC (SR-PVC) is mainly used as primary insulation and is very abrasion-resistant. SR-PVC insulation also had heat, water, acid, and alkali resistance, along with being flame-retardant. For 30-16 gauge wire, a 10-mil. wall meets the UL-style UL 1061 (80 degrees Celsius, 300 volts).

Plenum Polyvinyl Chloride (Plenum PVC)

Plenum Polyvinyl Chloride (Plenum PVC) insulation is suitable for use in plenum spaces -- building spaces behind dropped ceilings or raised floors left open to allow for air circulation. Standard PVC is considered a non-plenum insulation option because it does not exhibit the qualities necessary for safe usage in plenum areas. To be plenum-rated, the insulation must meet more-stringent fire safety regulations.

Polyethylene (PE)

Polyethylene (PE) Insulation is mostly used in coaxial and low-capacitance cables because of its exemplary electric qualities. It is often used in high performance applications because it is affordable and can be foamed to reduce the dielectric constant to 1.50. This makes polyethylene a popular insulation option for cables requiring high-speed transmission. Wire and cable with polyethlene insulation can be used in operating temperatures ranging from -65° Celsius to +80° Celsius. All PE insulation is stiff, hard, and inflexible at all densities. PE insulation is also flammable. Additives can be used to make PE insulation flame-retardant, but doing this will sacrifice the dielectric constant and increase power loss.

Polypropylene (PP)

Polyproylene insulation (PP) is very similar to polyethylene (PE) insulation, but has a wider temperature range of -30° Celsius to +105° Celsius. PP insulation is commonly used primarily for thin-wall primary insulations and can be foamed to improve its electrical properties.

Polyurethane (PUR)

Polyurethane (PUR) insulation is known for its extreme toughness, flexibility, and flex life; even in low temperatures. It also has excellent ratings for chemical, water, and abrasion resistance. PUR insulation works well in retractile cord applications and is a popular option for salt-spray and low-temperature military purposes. However, polyurethane is a flammable material. PUR insulation can be made flame-retardant with additives, but doing this sacrifices some insulation strength and affects the surface finish. Although polyurethane is generally very durable, it has poor electrical properties, making PUR more commonly used for wire and cable jacketing rather than as an insulation material.

Chlorinated Polyethylene (CPE)

Chlorinated Polyethylene (CPE) insulation has very good heat, oil, and weather resistance and commonly serves as a lower-cost, more environmentally friendly alternative to chlorosulfonated polyethylene (Hypalon / CSPE) insulation. CPE insulation also has reliable performance when exposed to fire and flame; making CPE insulation a favorable alternative to PVC insulation. Chlorinated polyethylene insulation is commonly found in power and control cables, as well as industrial power plant applications.

Nylon

Nylon is usually extruded over softer insulation compounds. It serves as a tough jacket, exhibiting strong abrasion, cut-through, and chemical resistance, especially in thin-wall applications. Nylon is also extremely flexible. One disadvantage of nylon is its absorption of moisture. This degrades some of its electrical properties.

Comparative Properties of Plastic Insulations

	PVC	PE	LD PE	Cellular PE	HD PE	PP	Cellular PUR	PVC	Plenum Nylon	CPE
Oxidation Resistance	E	E	E	E	E	E	E	E	E	E
Heat Resistance	G-E	G	G	E	E	E	G	G-E	E	E
Oil Resistance	F	G-E	G	G-E	F	F	E	F	E	E
Low-Temperature Flexibility	P-G	E	E	E	P	P	G	P-G	G	E
Ozone Resistance	E	E	E	E	E	E	E	E	E	E
Weather (Sun Resistance)	G-E	E	E	E	E	E	G	G	E	E
Abrasion Resistance	F-G	G	F	E	F-G	F-G	O	F-G	E	E-O
Electrical Properties	F-G	E	E	E	E	E	P	G	P	E
Flame Resistance	E	P	P	P	P	P	P	E	P	E
Nuclear Radiation Resistance	F	G-E	G	G-E	F	F	G	F	F-G	O
Water Resistance	F-G	E	E	E	E	E	P-G	F	P-F	O
Acid Resistance	G-E	G-E	G-E	E	E	E	F	G	P-F	E
Alkali Resistance	G-E	G-E	G-E	E	E	E	F	G	E	E
Alcohol Resistance	P-E	E	E	E	E	E	P-G	G	P	E
Aliphatic Hydrocarbons Resistance	P	G-E	G	G-E	P-F	P	P-G	P	G	E
Aromatic Hydrocarbons Resistance	P-F	P	P	P	P-F	P	P-G	P-F	G	G-E
Halogenated Hydrocarbon Resistance	P-F	G	G	G	P	P	P-G	P-F	G	E
Underground Burial	F-G	G	-	G	-	-	G	P	-	P

P = POOR	F = FAIR	G = GOOD	E = EXCELLENT	O = OUTSTANDING

Rubber Insulation Types

Thermoplastic Rubber (TPR)

In many applications, Thermoplastic Rubber (TPR) insulation is used to replace true thermoset rubber. TPR has improved colorability, higher processing speeds, and a wider usable temperature range. TPR also displays excellent heat, weather, and age resistance without curing. Thermoplastic rubber insulation is not cut-through resistant, but can be utilized in applications where other properties of rubber are preferred.

Neoprene (Polychloroprene)

Neoprene (Polychloroprene) insulation is a synthetic thermoset rubber that must be vulcanized to obtain its desired qualities. Neoprene exhibits supreme abrasion, cut-through, oil, and solvent resistance. Neoprene is also known for its long service life, wide temperature range, and usability. It is remarkably flame retardant and self-extinguishing. Neoprene is especially desirable for hand-held cord sets and is often used in Military applications.

Styrene-Butadiene Rubber (SBR)

Styrene-Butadiene Rubber (SBR) Insulation is a thermoset compound with qualities similar to neoprene. SBR insulation has a temperature range of -55° Celsius to +90° Celsius and is primarily used in Mil-C-55668 cables.

Silicone

Silicone insulation is extremely heat-resistant, flame-retardant, and can be used in operating temperatures up to +180° Celsius. Silicone is moderately abrasion-resistant and extremely flexible. Other benefits of silicone insulation include a long storage life and good bonding properties; two features which are commonly required for many electrical applications.

Fiberglass

Fiberglass is the most widely used glass insulation and can be used continuously in operating temperatures up to +482° Celsius. Although fiberglass is resistant to moisture and chemicals, it only has average abrasion-resistance. Common applications of fiberglass include heat treating, glass and ceramic kilns, foundries, and extensive applications in aluminum processing.

Ethylene Propylene Rubber (EPR)

Ethylene Propylene Rubber (EPR) insulation is known for its excellent thermal characteristics and electrical properties, allowing a smaller cross-sectional area for the same load-carrying capacity of other cables. It is commonly used in high-voltage cables. EPR insulation is heat, oxidation, weathering, water, acid, alcohol, and alkali-resistant, and is commonly used in high-voltage cables. The flexibility of EPR insulation also makes it appropriate for temporary installations and applications in the mining industry. Although EPR is very flexible, it is also a relatively soft material, and may require more care during installation to avoid damage. Ethylene Proplyene Rubber insulation has an operating temperature range from -50° Celsius to +160° Celsius like other common insulation materials, but EPR is also not as tear-resistant as other insulation options.

Rubber

Rubber insulation generally refers to both natural rubber and SBR compounds, each available in a variety of formulas for use in a wide range of applications. Because formulas vary, so do the operating temperature ranges and some other basic characteristics. While rubber insulation has poor oil and ozone resistance, it exhibits good low-temperature flexibility and electrical properties, as well as water, alcohol, and abrasion resistance.

Chlorosulfonated Polyethylene (CSPE)

Chlorosulfonated Polyethylene (CSPE) insulation works well in low-voltage applications. CSPE insulation is known for its ability to perform in a wide temperature range, as well as its resistance to chemicals and UV rays. CSPE insulation can be commonly found in appliance wire, lead wire, coil leads, transformer leads, and motor lead wire. Chlorosulfonated Polyethylene is also referred to as Hypalon, a registered trademark of Dupont.

Ethylene Propylene Diene Monomer (EPDM)

Propylene Diene Monomer (EPDM) insulation is a synthetic rubber insulation that displays outstanding heat, ozone, weather, and abrasion resistance. EPDM insulation also exhibits excellent electrical properties. Further benefits of EPDM insulation include excellent flexibility at both high and low temperatures, ranging from -55° Celsius to +150° Celsius, as well as having a good dielectric strength. Propylene Diene Monomer is commonly used as a replacement material for silicone rubber in some applications.

Comparative Properties of Rubber Insulations

	Rubber	Neoprene	CSPE	EPDM	Silicone
Oxidation Resistance	F	G	E	E	E
Heat Resistance	F	G	E	E	O
Oil Resistance	P	G	G	P	F-G
Low-Temperature Flexibility	G	F-G	F	G-E	O
Ozone Resistance	P	G	E	E	O
Weather (Sun Resistance)	F	G	E	E	O
Abrasion Resistance	E	G-E	G	G	P
Electrical Properties	G	P	G	E	G
Flame Resistance	P	G	G	P	F-G
Nuclear Radiation Resistance	F	F-G	E	G	E
Water Resistance	G	E	E	G-E	E
Acid Resistance	F-G	G	E	G-E	F-G
Alkali Resistance	F-G	G	E	G-E	F-G
Alcohol Resistance	G	F	G	P	G
Aliphatic Hydrocarbons Resistance	P	G	F	P	P-F
Aromatic Hydrocarbons Resistance	P	P-F	F	F	P
Halogenated Hydrocarbons Resistance	P	P	P-F	P	P-G

P = POOR	F = FAIR	G = GOOD	E = EXCELLENT	O = OUTSTANDING

Fluoropolymer Insulation Types

Perfluoroalkoxy (PFA)

Perfluoroalkoxy (PFA) insulation has different operating temperature ratings depending on the cables' construction, ranging from -65° Celsius to +250° Celsius. PFA insulation also has a very low dissipation factor, making it an electrically efficient option. Although PFA can be processed in long lengths, it is also an expensive material and does not exhibit thermoset qualities, limiting the use of PFA insulation to select application.

Polytetrafluoroethylene (PTFE)

Polytetrafluoroethylene (PTFE) insulation is a thermoplastic material that has an operating temperature range of -73° Celsius to +204° Celsius. PTFE insulation is extremely flexible, as well as resistant to water, oil, chemicals, and heat. The mechanical properties of PTFE are low compared to other fluoropolymer materials.

Fluorinated Ethylene Propylene (FEP)

Fluorinated Ethylene Propylene (FEP) insulation is mostly used because of its processing characteristics and wide range of application uses. FEP insulation is also highly flame-resistant. Improved data transmission can also be achieved when FEP is foamed. Pricing and processing are also being improved. Fluorinated Ethylene Propylene insulation is commonly used in plenum cable and military applications.

Ethylene Tetrafluoroethylene (ETFE) and Ethylenechlorotrifluoroethylene (ECTFE) Halar

Ethylene Tetrafluoroethylene (ETFE) and Ethylenechlorotrifluoroethylene (ECTFE) are stronger insulation materials and more flexible than PFA or FEP insulation. ETFE and ECTFE insulation can also become thermoset through irradiation. Foaming ECTFE and ETFE improves data transmission and reduces weight. However, ETFE and ECTFE lack many of the electrical advantages that FEP insulation provides.

Polyvinylidene Fluoride (PVDF)

Polyvinylidene Fluoride (PVDF) is a flexible, lightweight, and thermally stable insulation material. PVDF insulation is also resistant to chemicals, heat, weather, abrasion, and fire. PVDF is a relatively low-cost insulation option, so it is used in a wide range of industries and applications. Polyvinylidene Fluoride is often found in cables that need to meet the UL standard 910 Plenum Cable Flame Test, which labels cables as suitable for use in a building’s space for air circulation. PVDF is also commonly called Kynar, a registered trademark of Arkema Inc.

Thermoplastic Elastomers (TPE)

Thermoplastic elastomers (TPE) consist of a mix of polymers, typically plastic and rubber, to combine the benefits of each material into one insulating product. TPE can be molded, extruded, and reused like plastic materials while still maintaining the flexibility and stretch of rubber. Thermoplastic elastomers are commonly used in applications where conventional elastomers cannot provide the necessary range of physical properties. TPE insulation is now being more and more commonly used in household appliances and automotive applications. Disadvantages of TPE insulation include poor chemical and heat resistance, low thermal stability, and an overall higher cost when compared to other types of insulation.

Comparative Properties of Fluoropolymer Insulations

	FEP	ETFE	PTFE	PVDF	ECTFE	TPE
Oxidation Resistance	O	E	O	O	O	E
Heat Resistance	O	E	O	O	O	E
Oil Resistance	O	E	E-O	E	O	G
Low-Temperature Flexibility	O	E	O	F	O	E
Ozone Resistance	E	E	O	E	E	E
Weather (Sun Resistance)	O	E	O	E-O	O	E
Abrasion Resistance	E	E	O	E	E	F-G
Electrical Properties	E	E	E	G-E	E	E
Flame Resistance	O	G	E	E	E-O	F-G
Nuclear Radiation Resistance	P-G	E	P	E	E	G
Water Resistance	E	E	E	E	E	G-E
Acid Resistance	E	E	E	G-E	E	G
Alkali Resistance	E	E	E	E	E	G-E
Alcohol Resistance	E	E	E	E	E	G
Aliphatic Hydrocarbons Resistance	E	E	E	E	E	P
Aromatic Hydrocarbons Resistance	E	E	E	G-E	E	P
Halogenated Hydrocarbonic Resistance	E	E	E	G	E	-
Underground Burial	E	E	E	E	E	P

P = POOR	F = FAIR	G = GOOD	E = EXCELLENT	O = OUTSTANDING