Differences Between THHN THWN Wire

Differences Between THHN & THWN Wire

Electricity isn’t delivered through one form of wire. There are several versions of conductors on the market. They vary as to their use and the amount of electricity they handle. Three are THHN, THWN, and XHHW wire.

What are THHN and THWN Wires?

When it comes to THHN vs THWN the main difference is their resistance. Thus, they’re utilized in different areas within the construction industry.

The THWN wire meaning is short for Thermoplastic High Water-resistant Nylon-coated. In THHN, water is replaced with heat. Basically, they differ due to the maximum heat and water they take before damage or failure.

Of the two, THWN wire has the highest tolerance. When it comes to THHN vs THWN-2 wire, the latter withstands a maximum temperate of 90 degrees Celcius (194 Fahrenheit) in both dry and wet environments. Conversely, THHN has a top tolerance of 75 degrees Celcius or 175 Fahrenheit.

What is XHHW Wire?

In a comparison between XHHW vs THHN, the latter is the stronger one. It’s an acronym for a wire that is resistant to high heat and water. The XHHW-2 version of the product withstands temperatures of 90 degrees Celcius while the standard one resists water and heat up to 75 degrees Celcius. In most industries, XHHW-2 has superseded the original version of the wire.


The main difference between XHHW-2 wire and the THHN/THWN family comes down to insulation. The latter two are shielded by polyvinyl chloride. Commonly known as PVC, it is the third-most widely produced plastic polymer around the globe. Though it has enormous strength and fire resistance, it could produce toxic smoke if burned.

There’s another issue with PVC. Since it’s thinner, there’s a greater chance for current leakage. Not only does this increase power fluctuations but it also could trip breakers every few days. Continual leakage also results in eventual breakdowns.

On the other hand, XHHW-2 is insulated with cross-linked polyethylene (XLPE). This is used in industries and construction that deal with extreme temperature shifts. This includes high-tension electrical cables and the wires inside them.

Also Read: Types of Electrical Wiring in Commercial Buildings

Uses of THHN, THWN, and XHHW Wire

Despite some of its downfalls, THHN wire continues to be extremely popular in the construction sector. It’s utilized in industral, commercial, and residential buildings. Since it handles up to 600 volts, THHN wire covers the usage of most appliances.

THWN is also popular in construction. It’s the greatest use is in areas where there’s a potential for water usage or damage. As it’s resistant at higher temperatures than THHN, THWN wire is best used in locations like underground conduits.

XHHW wire has the same purposes as THWN. In other words, it works best in either dry or wet environments. Due to its insulation, there’s less risk for current leakage. Thus, it’s used for power distribution systems, feeders, and branch circuits.

Needless to say, THWN, THHN, and XHHW wires are commonly used in cables that deliver electricity to our homes and businesses. Their development over the years has reduced the potential of constant breakdowns in excessive heat and water environments. Overall, XHWW is the most useful.

What you utilize within your business depends on your preference and what your customer needs. Consider the return on investment for these wires when you start a construction project. The result could be a long life free of electrical issues or potential breakdowns in the future.

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