Which type of conductor is approved for installation in a wet location?

• A. THHN
• B. THHW
• C. THWN
• D. XHHW

Answer: (B)

The key idea is that conductors used in wet locations must have insulation rated for moisture exposure. THHW stands for Thermoplastic Heat-and-Water-Resistant insulation, so it is designed to resist water and is approved for wet locations. That explicit water resistance is what makes it suitable for wet environments, such as outdoors or in damp spaces. The other options either emphasize dry-use insulation (THHN) or are typically associated with use in wet locations but are not the one specified by this question as the primary wet-location conductor. So THHW is the best match for installation in a wet location.