What is the most common insulation type used for conductors in HVAC applications?

The most common insulation type used for conductors in HVAC applications is thermoplastic insulation, such as THHN. This type of insulation is preferred due to its durability, flexibility, and resistance to heat, moisture, and corrosion. Thermoplastic materials can withstand higher temperatures while maintaining excellent electrical performance, making them suitable for a variety of HVAC applications where ruggedness and reliability are essential.

Additionally, THHN is designed for use in wet or dry locations, which is a significant advantage in HVAC environments where moisture can be a factor. This versatility makes THHN a go-to choice for wiring in heating, ventilation, and air conditioning systems. Its strong mechanical properties also help in reducing the risk of damage during installation and operation.

While rubber insulation provides flexibility and good electrical properties, it is not as commonly used as thermoplastic for general HVAC applications due to considerations like heat resistance and cost. Fiberglass insulation, on the other hand, is primarily used for thermal insulation rather than electrical conductor insulation. Polyethylene insulation is used in specific applications but lacks the broad utility and performance characteristics of thermoplastic options like THHN in HVAC contexts.