If service entrance conductors are larger than 1100 kcmil, then the GEC needs to be 12.5% of the cross sectional area. Does this requirement only apply if ANY conductor is larger than 1100 kcmil or if the combined area is larger? In other words, do parallel sets apply to this rule where the combined area of the parallel sets exceeds 1100 kcmil.
Grounding electrode conductor - 12.5%
- Thread starter cppoly
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- New Jersey
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- Journeyman Electrician
There is no 12.5% rule for GEC's. The largest ever required in T250.66 is #3/0 copper.
ArcLazerbeam
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- VT
I believe 250.24 (c)(2) will direct you to 250.102(c)(1). But in your case you want table 250.66
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- Logan, Utah
Correct, the 12.5% rule only applies to Main boding jumpers, system bonding jumpers, and supply side bonding jumpers.
For grounding electrode conductors the largest that is necessary is a 3/0.
(See 250.102(C) and the accompanying table in the 2014 NEC)
Chris
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