THHN THWN THW Acronym Meanings
THHN, THWN and THW are all types of single conductor electrical wire used in homes and buildings to deliver power. Years ago, each acronym was a completely different wire with different approvals. Each type was specific to an application and cost as such. One with a nylon coating, for instance, was more expensive than one without. However, nowadays, there is a universal THHN-2 wire that covers all approvals from all variations of THHN, THWN and THW.
THHN Wire and THWN Wire
Thermoplastic, high heat, Nylon coated. THHN wire without a dual approval of THWN is not water resistant. The added "W" stands for water resistant so that it could be installed outdoors and in conduit when THHN wire could not. However, again, remember that they're all combined into a universal wire now. If you buy THHN wire on our website it will have all of the attributes of each acronym discussed on this page.
Thermoplastic, Heat and water resistant wire. This acronym is missing the "N" for nylon coated. The nylon coating looks like the little piece of plastic over a shoe lace and protects the wire in a similar fashion. Without the nylon coating, the wire will be slightly cheaper and provide less environmental protection to THW wire. It's actually difficult to find THW wire without the additional approvals of THHN and THWN because they were all combined into one.
You can probably imagine how difficult it was to design, manufacture, stock, and price each of the separate types of electrical wire. That's why they were combined into a universal THHN-2 wire at a very attractive price.
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