Dịch vụ & Phân phốiCâu 97 / 521
The minimum depth of working space in front of a 208Y/120 V panelboard (0-150 V to ground, Condition 1: exposed live parts on one side, no live or grounded parts on the other) is:
a.2.5 ft
b.6 ft
c.3 ft
d.4 ft
Giải thích
Per Table 110.26(A)(1), for equipment 0-150 V to ground under Condition 1, the minimum working clearance is 3 ft (900 mm). Greater depths (4 ft, 6 ft) apply to higher voltages or worse conditions, and 2.5 ft is never a permitted minimum for this equipment.
Trích dẫn luật: 2023 NEC §110.26Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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