FACTORS THAT SET XHHW-2 APART FROM THHN
Thermoplastic and thermoset are two types of cable insulations commonly used for single conductors. It’s important to understand their strengths and weaknesses when designing and building a new facility, machine, or appliance.
THHN/THWN-2 is a thermoplastic product. It uses a thinner PVC insulation, which can lead to current leakage and dielectric breakdown in demanding circuits or from chemical or environmental exposure. The PVC insulation in THHN/THWN-2 emits a toxic smoke when burned and is less flexible at cold temperatures. However, it is lighter in weight and less expensive to manufacture.
Thermoplastic compounds can be heated, then shaped and cooled to maintain their desired shape. This process can typically be repeated by applying heat to remelt the insulation, which can lead to potential danger in some applications.
Examples of thermoplastic compounds include:
- Polyvinyl Chloride (PVC)
- Polyethylene (PE)
- Polypropylene (PPE)
XHHW-2 is a thermoset product. Crosslink products like XHHW-2 have XLPE (crosslinked polyethylene) insulation instead of PVC. XLPE is more resistant to chemicals, ozone, and abrasions. Because of the chemistries involved, modern XLPE is far less toxic than PVC in the event of fire. In more applications, thermosets are more flexible than thermoplastics and are more advantageous for projects where complex, close-spaced bends are required.
Thermoset compounds utilize a curing process which causes a chemical reaction, allowing the polymers to cross-link. Once cured, the thermoset compounds retain their shape and will not remelt when heat is applied.
Examples of thermoset compounds include:
- Crosslinked Polyethylene (XLP/XLPE)
- Ethylene Propylene Diene Terpolymer (EPDT)
- Chlorinated Polypropylene (CPE)
- Crosslinked Polyolefin (XLPO)
- Silicone Rubber