Core TradesCâu 136 / 700
A concrete-encased electrode ('Ufer' ground) used as a grounding electrode must include at least how many feet of bare steel rebar or copper conductor encased in the footing?
a.10 feet
b.30 feet
c.50 feet
d.20 feet
Giải thích
A concrete-encased electrode must consist of at least 20 feet of 1/2-inch (or larger) bare rebar or 4 AWG copper encased in at least 2 inches of concrete near the bottom of a foundation. The moist concrete-to-earth contact makes it a very effective electrode. 10 feet is insufficient; 30 and 50 feet exceed the minimum.
Trích dẫn luật: 2025 CA Electrical Code, Art. 250.52Luyện miễn phí toàn bộ 700 câu hỏi — không cần đăng ký.
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