Wiring Methods & MaterialsCâu 83 / 120
Conductors installed in an underground raceway in a wet location must have which characteristic?
a.A nylon jacket, which by itself qualifies the conductor for wet locations
b.Any thermoplastic insulation, since the raceway keeps water out
c.Insulation rated 90 degrees C, regardless of wet-location listing
d.Insulation listed for use in wet locations, such as THWN or THWN-2
Giải thích
Raceways in underground and other wet locations are considered wet inside, so the conductors must carry a wet-location listing such as THWN, THWN-2 or XHHW. The W in the type designation is what matters; plain THHN without the dual THWN-2 marking is a dry- and damp-location conductor, and a temperature rating or nylon jacket alone does not confer a wet-location listing.
Trích dẫn luật: 2023 NEC §310.10(C)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- An angle pull box has one 2-inch raceway and one 1-inch raceway entering the same wall, with conductors turning 90 degrees. What is the minimum distance from that wall to the opposite wall?
- How must liquidtight flexible metal conduit be secured on a normal run?
- How many 12 AWG conductors may be installed in a 4-11/16 inch by 2-1/8 inch square box with a volume of 42.0 cubic inches, assuming no clamps, devices or fittings?
- Direct-buried conductors emerging from grade must be protected by an approved enclosure or raceway from below grade to what height?
- What is the maximum fill percentage when exactly two conductors are installed in a raceway?
- What is the minimum trade size of EMT required for twenty-four 12 AWG THHN conductors?
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