TRANSFORMER SECONDARY CONDUCTORS

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ohmhead

ohmhead

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ORLANDO FLA
infinity said:
He could be using the 12.5% rule for the SSBJ in each raceway but it's not required. If you had only one raceway, say a wireway, then you would have only one SSBJ which would need to be sized according to the 12.5%.
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OK that's whats confusing if its a SSBJ in raceway and 250 .66 says 250 alu in the 2014 code book table 250 .(c)(1) says see notes which is 12.5% and I know its not used in this case but table 250.122 shows if I had a 2000 amp breaker a 400 mcm in raceway with phase & neutral which is close to 12.5% used in 250(c)(1) . I just don't see the logic here when you say he could have but a 3/0 is ok .
So is it the combined total mcm of all raceways or he could have installed a 3/0 in one or each of the raceways ?
 
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infinity

infinity

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Location
New Jersey
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Journeyman Electrician
ohmhead said:
OK that's whats confusing if its a SSBJ in raceway and 250 .66 says 250 alu in the 2014 code book table 250 .(c)(1) says see notes which is 12.5% and I know its not used in this case but table 250.122 shows if I had a 2000 amp breaker a 400 mcm in raceway with phase & neutral which is close to 12.5% used in 250(c)(1) . I just don't see the logic here when you say he could have but a 3/0 is ok .
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Just remember the #3/0 is not a singular SSBJ, there are actually six of them connected at both ends in parallel.
 
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