Beyond conductivity, another important consideration when choosing an electrical cable is its insulation. Nowadays, common electrical cables are typically insulated with one of two popular materials: polyvinyl chloride (PVC) or cross-linked polyethylene (XLPE).
Making the right choice between the two materials comes down to understanding their differences, and accounting for your project’s required insulation, temperature tolerance, flexibility, durability, budget range, and other relevant factors.
What is PVC?
Polyvinyl chloride (PVC) is a synthetic plastic polymer. Being a thermoplastic, it softens when heated and hardens when cooled. Flexible, versatile, and cost-effective, PVC insulation is an excellent and economical choice for various environments ranging from residential to industrial, available at a more affordable price point than XLPE cables.
What is XLPE?
Like PVC, cross-linked polyethylene (XLPE) is also a synthetic plastic polymer. XLPE is created through the chemical process of cross-linking polyethylene. From thermoplastic, it becomes thermoset, and will no longer soften or melt in extreme heat—making it thermally stable, mechanically strong, and hardy in high-temperature environments.
PVC and XLPE: A Side-by-Side Comparison
Voltage Rating
PVC insulation is suitable for low-voltage and limited medium-voltage applications, typical of household wiring, small-scale industrial applications, and some machinery.
XLPE-insulated cables, on the other hand, can be safely used in medium- to high-voltage applications, such as grid power distribution and large-scale industrial operations.
Temperature Range
Generally, PVC-insulated cables can continuously operate in temperatures up to 70°C, with some specialized PVC cables withstanding up to 90°C, such as Phelps Dodge’s Permalite® THHN/THWN-2 Building Wire. At higher or fluctuating temperatures, most PVC cables run the risk of insulation failure, deformation, and degradation—so indoor use in stable temperatures is recommended.
As protection and prevention, Phelps Dodge’s PVC-insulated THHN/THWN-2 wires all ace intensive heat aging tests exposing them to temperatures up to 136°C for seven days. However, the best way to deter danger and maximize a cable’s lifespan is to strictly follow its stated temperature rating at all times.
Meanwhile, XLPE-insulated cables can tolerate temperatures up to 90°C under normal operations. Thanks to the cross-linking process, XLPE can endure even in elevated temperatures while keeping its shape, insulation properties, and mechanical integrity intact. This makes it suitable for outdoor applications and industrial facilities, where it may be safely exposed to direct sunlight and high heat.
Fire Resistance and Safety
PVC strengthens the safety of an installation with its flame retardance. This means that if it catches fire, once the fire source is removed, the cable will self-extinguish. However, it must be noted for precaution that when PVC burns, it can emit toxic and corrosive gases, such as hydrogen chloride and dioxins.
XLPE, on the other hand, can be manufactured to have low-smoke, halogen-free (LSHF) properties, like Phelps Dodge’s Solar Cable. LSHF cables will not release toxic or corrosive gases when burning, reducing harm to humans, equipment, and the environment in case of a fire.
LABEL: Phelps Dodge Low Smoke Halogen Free (LSHF) Fire-Rated Wire
Chemical Resistance
PVC insulation is resistant to a wide range of acids and alkalis. As XLPE insulation exhibits a higher degree of resistance to most oils, solvents, and chemicals, it is better equipped to handle challenging industrial environments where hazardous substances abound.
Mechanical Strength
PVC-insulated cables are advantageous for their flexibility, which makes them easy to use in applications requiring bending or routing through tight spaces. However, too much mechanical stress can damage the insulation.
Due to its cross-linked structure, which gives it better tensile strength and resistance to wear and tear, XLPE is usually preferred for applications prioritizing strength over flexibility, such as outdoor applications or those involving heavy machinery.
Choosing Safely and Wisely
The choice between PVC and XLPE for cable insulation ultimately depends on your installation’s requirements. Factors include the type of environment, the mechanical and chemical stresses that may affect the cable, routing needs, your budget, and other important considerations.
Phelps Dodge offers a diverse range of both PVC- and XLPE-insulated cables, expertly engineered to stand the test of time and provide lifelong protection. Inquire now to select the best cable for your installation!
