Theory & SafetyCâu 116 / 120
A 480-volt panelboard is mounted on a wall with a grounded concrete wall directly behind the working space. What is the minimum depth of working space?
a.2 and 1/2 feet
b.3 feet
c.4 feet
d.3 and 1/2 feet
Giải thích
For nominal voltages of 151 to 600 volts to ground, Condition 2 exists when exposed live parts face a grounded surface such as a concrete or masonry wall, and the required depth is 3 and 1/2 feet. Condition 1, with no live or grounded parts opposite, requires 3 feet, and Condition 3, with exposed live parts on both sides, requires 4 feet.
Trích dẫn luật: 2023 NEC §110.26(A)(1)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
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