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Friday, June 28, 2019
Question:
250 Amp Service Feed with 350 ALU ground size
Charles Gaddy
A
Answer:
Hey Charles thanks for your question. Service grounded conductors are sized using Table 250.102(C)(1) as stated in 250.24(C)(1). For 350 kcmil aluminum ungrounded conductors use the second column with the range of over 250 through 500 (kcmil). The grounded conductor must be at least a 2 AWG if copper, from the third column, or a 1/0 if aluminium, from the fourth column. Compare that size (depending on which material is being used) with the load calculation in 220.61 and use the larger size conductor.