Dịch vụ & Phân phốiCâu 111 / 521
A service raceway enters a building from an underground distribution system. To prevent moisture and gases from entering, the raceway must be:
a.Left open for drainage
b.Filled with concrete
c.Painted on the interior
d.Sealed with an approved material (though a drainage provision may still be provided)
Giải thích
Per 230.8, a raceway entering from an underground distribution system must be sealed with an identified compound to block moisture and gases; spare or unused raceways must also be sealed. Leaving it open or filling with concrete does not meet the sealing requirement, and painting does not seal against gas migration.
Trích dẫn luật: 2023 NEC §230.8Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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