Electrical Cable Insulation Materials

 

Common Electrical Cable Insulation Materials and Wire Types

Material / Type	Full Form	Temperature Rating	Typical Application
PVC	Polyvinyl Chloride	70°C	House Wiring
XLPE	Cross-linked Polyethylene	90°C	Power Cables
PE	Polyethylene	75°C	Communication Cables
EPR	Ethylene Propylene Rubber	90°C	Flexible Cables
LSZH	Low Smoke Zero Halogen	90°C	Fire Resistant Cables
THHN	Thermoplastic High Heat-resistant Nylon-coated	90°C (Dry), 75°C (Wet)	Building Wire, Conduit Wiring
THWN	Thermoplastic Heat and Water-resistant Nylon-coated	75°C (Wet), 90°C (Dry)	Industrial and Commercial Wiring
THWN-2	Thermoplastic Heat and Water-resistant Nylon-coated Type 2	90°C (Wet and Dry)	Feeders and Branch Circuits
XHHW	Cross-linked Polyethylene High Heat-resistant Water-resistant	90°C (Dry), 75°C (Wet)	Power Distribution
XHHW-2	Cross-linked Polyethylene High Heat-resistant Water-resistant Type 2	90°C (Wet and Dry)	Commercial and Industrial Power Cables

Description of THHN, THWN, and XHHW-2

THHN

• PVC insulation with Nylon jacket.
• High heat resistance.
• Used extensively in building wiring and control panels.
• 90°C dry, 75°C wet.

THWN

• Designed for wet and dry locations.
• PVC insulation with Nylon sheath.
• Common in industrial and commercial installations.
• 75°C wet, 90°C dry.

THWN-2

• Improved version of THWN.
• Rated 90°C in both wet and dry environments.
• Widely used in modern electrical systems.

XHHW

• XLPE insulation.
• Excellent moisture and chemical resistance.
• 90°C dry, 75°C wet.

XHHW-2

• Premium XLPE insulation.
• High dielectric strength and current carrying capacity.
• 90°C wet and dry.
• Used in power distribution systems, industrial plants, and utility applications.

Electrical Cable Insulation Materials & Wire Types (Complete List)

Material / Type	Full Form	Temperature Rating	Typical Application
PVC	Polyvinyl Chloride	70°C	House Wiring, General Wiring
FR-PVC	Flame Retardant PVC	70°C	Building Wiring, Safety Cables
HR-PVC	Heat Resistant PVC	85°C	Industrial Wiring
XLPE	Cross-linked Polyethylene	90°C	Power Cables, Underground Cables
PE	Polyethylene	75°C	Communication & Telecom Cables
HDPE	High Density Polyethylene	75°C	Fiber Optic & Telecom Sheathing
EPR	Ethylene Propylene Rubber	90°C	Flexible & Mining Cables
LSZH	Low Smoke Zero Halogen	90°C	Fire Safety Cables, Public Buildings
HFFR	Halogen Free Flame Retardant	90°C	Railway, Metro, Ship Wiring
FRLS	Flame Retardant Low Smoke	70–90°C	Indoor Wiring, Commercial Buildings
THHN	Thermoplastic High Heat-resistant Nylon-coated	90°C (Dry), 75°C (Wet)	Building Wire, Conduit Wiring
THWN	Thermoplastic Heat and Water-resistant Nylon-coated	75°C (Wet), 90°C (Dry)	Industrial Wiring
THWN-2	Thermoplastic Heat and Water-resistant Nylon-coated Type 2	90°C (Wet & Dry)	Feeders, Branch Circuits
XHHW	Cross-linked Polyethylene High Heat-resistant Water-resistant	90°C (Dry), 75°C (Wet)	Power Distribution
XHHW-2	Cross-linked Polyethylene High Heat-resistant Water-resistant Type 2	90°C (Wet & Dry)	Industrial & Commercial Power Cables
NYY	PVC Insulated & Sheathed Cable	70°C	Power Distribution (Europe standard)
NYM	PVC Installation Cable (multi-core)	70°C	Fixed Wiring in Buildings
A/V Cable (Silicone)	Silicone Rubber Insulated Cable	180°C	High Temperature Industrial Equipment

Important Notes

• LSZH / HFFR / FRLS are mainly used where fire safety and low toxic smoke is required.
• THHN / THWN / XHHW-2 are mostly used in US NEC standard wiring systems.
• XLPE / PVC / EPR are global industrial standards in cable manufacturing.

Common Insulation Defects

Defect	Causes	Solution
Rough Surface	Low temperature	Increase barrel temperature
Burn Marks	Excessive temperature	Reduce temperature
Eccentric Insulation	Improper centering	Adjust die and tip
Air Bubbles	Moisture in compound	Dry material before use
Diameter Variation	Unstable line speed	Synchronize line speed
Poor Finish	Dirty die or cooling issues	Clean die and optimize cooling

Insulation Process 

Printing and Marking

Cable information printed includes:

• Manufacturer Name
• Cable Size
• Voltage Grade
• Standard
• Year of Manufacture
• Meter Marking

Example:

Company Name 3 x 120 mm.sq AL/XLPE/PVC/SWA/PVC 15-kv ELECTRIC CABLE 
IEC 60502-2 Year 2026 Meter Marking
Relevant Standards
IEC 60227 (PVC Insulated Cables)
IEC 60502 (Power Cables)
ASTM International
ISO 9001