Choosing between THHN & XHHW wire

Written by Admin | Oct 10, 2017 5:00:00 AM

Weighing the differences between THHN/THWN-2 & XHHW/XHHW-2 building wire

When it comes to building wire, two of the most common and popular choices for electricians, engineers & homeowners are THHN and XHHW (or the newer and improved THWN/THWN-2 and XHHW-2). These cables come in both copper and aluminum, can have solid or stranded conductors, and are mainly used for power distribution up to 600 volts in the construction of residential, commercial, and industrial buildings.

While these two wire types are very similar and often interchangeable in their application, the differences are important to know in order to make the smartest decision when making a building wire purchase.

Wire Jacket & Insulation

The main difference between XHHW/XHHW-2 and THHN/THWN-2 is in the wire’s jacket. The different letters in names denote particular properties of each cable, and each provides the cable with varying levels of insulation:

THHN

T for Thermoplastic
HH for High Heat-Resistant, and
N for Nylon Coated

Temperature rating: 90ºC in dry locations

XHHW

X for Cross-Linked Polyethylene (XLPE)
HH for High Heat-Resistant, and
W for Water Resistant

Temperature rating: 90ºC in dry, 75ºC in wet locations

THWN or THWN-2

T for Thermoplastic
H for Heat and
W for Water Resistant, and
N for Nylon Coated.

THWN temperature rating: 90ºC in dry, 75ºC in wet locations

THWN-2 temperature rating: 90ºC in both dry and wet locations

XHHW-2

XHHW-2 has the same properties as XHHW, but the "-2" denotes improved insulation.

XHHW-2 temperature rating: 90ºC in both dry and wet locations

The jackets on the THHN family are thinner than those of XHHW wires. This means that, while more THHN can be fit into a raceway or fed through a conduit, its jacket doesn’t offer as much protection as the XHHW jacket —XHHW’s jacket coating is more resistant to chemicals, ozone and abrasions while THHN’s thin coating can lead to current leakage and can break down from chemical or environmental exposure, emitting a toxic smoke when burned.

Flexibility

Even though its jacket is thicker and more protective, XHHW is also more flexible than THHN wire. The XLPE insulation of the XHHW allows the cable to bend and flex better than the THHN’s PVC insulation —so XHHW is much easier to work with during the installation process.

Price

When comparing the price of the two wires, the equivalent gauge of XHHW costs somewhere between 5-20% more than its THHN counterpart.

Final Verdict

At the end of the day, the decision between using XHHW or THHN in their next project comes down to weighing performance versus budget. On one hand, THHN is the more popular cable with our customers and many would say it’s perfectly sufficient for what they need. On the other hand, XHHW has the features to provide increased efficiency and extended longevity.

Both cables are incredibly popular, each with unique characteristics that are advantageous in certain environments. The choice between the two really just boils down to the project at hand and the budget with which you have to work.

At Wire & Cable Your Way, we sell many sizes of THHN/THWN-2 & XHHW/XHHW-2 building wire with a wide range of colored jackets and sold either cut-by-the-foot or in spools. Follow the links below to check out our selection.

Shop THHN/THWN-2

Shop XHHW-2

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