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Friday, January 31, 2020
Question:
What size grounding electrode conductor is needed for a 200-ampere service if the service phase conductors are 250 kcmil aluminum? There is only one grounding electrode which is the Ufer ground.
Adam Ford
A
Answer:
Hi Adam, thanks for the question.
If the installation only has one concrete-encased grounding electrode (Ufer as you called it) then all that is required is a copper grounding electrode conductor not larger than 4AWG. A 250 kcmil aluminum ungrounded service conductor would generally require not less than 2 AWG copper using Table 250.66, but since there is only the single concrete-encased electrode, the provisions of 250.66(B) can be applied.