Bonding Jumpers

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jca0108

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In 250.28(D) it says supply conductors(plural) then it says "area of largest conductor"(singular).So if i had paralleled supply conductors, do i add total circular mils per phase, then do the 12.5%?
 
12.5% would be the case with parallel conductors cir. mils combined for each phase., If they are larger than 1100 kcm copper or 1750 KCM alum. Thus for anything else you would use T250.66
 
jca0108 said:
In 250.28(D) it says supply conductors(plural) then it says "area of largest conductor"(singular).So if i had paralleled supply conductors, do i add total circular mils per phase, then do the 12.5%?
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Yes, you would add the circular mils together of the paralleled conductors that comprise the largest ungrounded phase conductor. Keep in mind that paralleled conductors in essence are combine at each end to create a single large conductor.

The as Dennis has pointed out you would use table 250.66 unless the combine conductors equivalent circular mils exceeds the Table then you would use 12.5%.

Chris
 
Dennis Alwon said:
12.5% would be the case with parallel conductors cir. mils combined for each phase., If they are larger than 1100 kcm copper or 1750 KCM alum. Thus for anything else you would use T250.66
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I was leaning toward that in the real world(if I were the installer),just didnt know what the code meant, language is fuzzy.
 
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