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In this guide, we\u2019ll explain what THHN wire is<\/strong>, its key features, where it\u2019s used, and how it compares to other common types of electrical wire. Whether you’re an electrician, contractor, or DIYer, this article will help you choose the right wire for the job.<\/p>\n \\n\\n\\n What Is THHN Wire<\/p><\/div>\\n\\n<\/p>\n \\n<\/p>\n THHN<\/strong> is an acronym defined by the National Electrical Code (NEC), and it stands for:<\/p>\n \\n\\n<\/p>\n T<\/strong> \u2013 Thermoplastic insulation<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n H<\/strong> \u2013 Heat-resistant (up to 75\u00b0C)<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n H<\/strong> \u2013 (Again) Higher heat resistance (up to 90\u00b0C in dry locations)<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n N<\/strong> \u2013 Nylon jacket for mechanical protection<\/p>\n \\n<\/li>\n \\n<\/ul>\n \\n<\/p>\n So, THHN wire<\/strong> is a thermoplastic-insulated, heat-resistant wire with a durable nylon coating.<\/p>\n \\n\\n\\n<\/p>\n \\n<\/p>\n A standard THHN cable<\/strong> consists of:<\/p>\n \\n\\n<\/p>\n Conductor:<\/strong> Solid or stranded copper (or sometimes aluminum)<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n Insulation:<\/strong> PVC (polyvinyl chloride)<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n Jacket:<\/strong> Nylon sheath to improve abrasion and chemical resistance<\/p>\n \\n<\/li>\n \\n<\/ul>\n \\n<\/p>\n This construction makes THHN wire durable, lightweight, and easy to pull through conduit<\/strong>.<\/p>\n \\n\\n\\n<\/p>\n \\n<\/p>\n \ud83d\udd0c Voltage Rating:<\/strong> Up to 600V<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n \ud83c\udf21\ufe0f Temperature Rating:<\/strong><\/p>\n \\n\\n<\/p>\n 90\u00b0C (194\u00b0F) in dry locations<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n 75\u00b0C (167\u00b0F) in wet locations (when dual-rated as THWN)<\/p>\n \\n<\/li>\n \\n<\/ul>\n \\n<\/li>\n \\n \\t<\/p>\n \ud83d\udca7 Moisture Resistance:<\/strong> Good (especially when dual-rated THHN\/THWN)<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n \ud83d\udd25 Heat Resistance:<\/strong> Excellent for dry conditions<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n \ud83d\udcaa Mechanical Strength:<\/strong> Strong nylon jacket resists oil, gas, and abrasion<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n \ud83e\uddf1 Installation Method:<\/strong> Suitable for conduit and raceway only (not for direct burial without protection)<\/p>\n \\n<\/li>\n \\n<\/ul>\n \\n\\n<\/p>\n \\n<\/p>\n THHN wire is one of the most commonly used building wires in the U.S. It is widely used in:<\/p>\n \\n\\n<\/p>\n Commercial and residential building wiring<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n Power distribution panels and control circuits<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n Conduit installations<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n HVAC equipment<\/p>\n \\n<\/li>\n \\n \\t<\/p>\n Lighting and outlet wiring<\/p>\n \\n<\/li>\n \\n<\/ul>\n \\n<\/p>\n \\n<\/p>\n Note:<\/strong> THHN is not rated for direct burial unless installed in a conduit. For underground wiring, consider UF-B<\/strong> or USE-2<\/strong> wire types.<\/p>\n \\n<\/p><\/blockquote>\n \\n\\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/tr>\n \\n<\/thead>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/tr>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/tr>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/tr>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/p>\n \\n<\/tr>\n \\n<\/tbody>\n \\n<\/table>\n \\n<\/p>\n \\n<\/p><\/div>\n \\n<\/p><\/div>\n \\n<\/p><\/div>\n \\n<\/p>\n THHN is ideal for indoor conduit work, while THWN-2<\/strong> and XHHW<\/strong> provide better moisture protection for outdoor or wet locations.<\/p>\n \\n\\n\\n<\/p>\n \\n<\/p>\n What is THHN wire used for?<\/strong> \\n<\/p>\n Is THHN wire rated for outdoor use?<\/strong> \\n<\/p>\n Can I bury THHN wire directly in the ground?<\/strong> \\n<\/p>\n Is THHN copper or aluminum?<\/strong> \\n\\n\\n<\/p>\n \\n<\/p>\n At TOT Wire & Cable<\/strong>, we supply THHN wire<\/strong> in various sizes and colors, including:<\/p>\n \\n\\n<\/p>\n
\\n\\n<\/p>\n\ud83d\udd0d What Does ‘THHN’ Stand For?<\/h3>\n
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\\n\\n<\/p>\n\ud83e\uddea THHN Wire Construction<\/h3>\n
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\\n\\n<\/p>\n\u2699\ufe0f Key Features of THHN Wire<\/h3>\n
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\\n\\n<\/p>\n\ud83c\udfd7\ufe0f Common Uses of THHN Wire<\/h3>\n
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\\n\\n<\/p>\n\ud83c\udd9a THHN vs Other Wire Types<\/h3>\n
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\\n<\/p>\n \\n<\/p>\nWire Type<\/th>\n Temperature Rating<\/th>\n Wet Location Use<\/th>\n Direct Burial<\/th>\n Jacket<\/th>\n \\n<\/p>\n THHN<\/strong><\/td>\n 90\u00b0C dry, 75\u00b0C wet<\/td>\n Yes (if dual-rated as THWN)<\/td>\n No<\/td>\n Nylon-coated<\/td>\n \\n<\/p>\n THWN-2<\/strong><\/td>\n 90\u00b0C dry & wet<\/td>\n Yes<\/td>\n No<\/td>\n Nylon-coated<\/td>\n \\n<\/p>\n XHHW<\/strong><\/td>\n 90\u00b0C dry & wet<\/td>\n Yes<\/td>\n No<\/td>\n XLPE-coated<\/td>\n \\n<\/p>\n UF-B<\/strong><\/td>\n 60-90\u00b0C<\/td>\n Yes<\/td>\n Yes<\/td>\n Solid PVC<\/td>\n
\\n\\n<\/p>\n\ud83d\udca1 Frequently Asked Questions<\/h3>\n
\u2192 THHN is used in conduit for electrical wiring in buildings, especially for power distribution and branch circuits.<\/p>\n
\u2192 Yes, but only when installed in conduit. It\u2019s not UV-resistant or waterproof on its own.<\/p>\n
\u2192 No. THHN wire must be installed inside conduit if buried underground.<\/p>\n
\u2192 Most THHN wire is copper, but aluminum options are available for larger gauge power wiring.<\/p>\n
\\n\\n<\/p>\n\ud83d\udce6 Available THHN Wire Sizes<\/h3>\n