Dịch vụ & Phân phốiCâu 53 / 521
What is the minimum depth of working space in front of a 120/240 V panelboard (Condition 1, exposed live parts on one side)?
a.2 ft (0.6 m)
b.4 ft (1.2 m)
c.3.5 ft (1.07 m)
d.3 ft (0.9 m)
Giải thích
Per Table 110.26(A)(1), Condition 1 for systems 0-150 V to ground requires 3 ft (900 mm) of clear working depth. 2 ft is too shallow, and 3.5 ft/4 ft apply to higher-voltage or Condition 2/3 situations.
Trích dẫn luật: 2023 NEC §110.26Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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