neutral for each conductor?

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jerry dutton

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I was asked a question from a former collegue......It appears he was getting an inspection from the architects and engineers on a job he is doing. He had a wire trough above a panel with all the branch circuits hanging there and the engineer said " we have a problem". He proceded to tell my old friend that each "hot" had to have its own neutral, or if the neutral is shared it must be "upsized". He also said this was in 2008 code. I always thought up to a,b,c phase could share a neutral. Please advise
 
charlie b

charlie b

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Lockport, IL
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Retired Electrical Engineer
The engineer is wrong. You can share a neutral with phases A, B, and C. If you do, you will need to employ a 3-pole breaker, or use a handle tie to connect the handles of the three single pole breakers. That is a change in 2008. If there is a concern over harmonic currents, then it would be wise to upsize the neutral. But I don't know if a specific code article would require that action.
 
charlie b

charlie b

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Lockport, IL
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Retired Electrical Engineer
In that case, the engineer should not have made the (incorrect) claim that the 2008 NEC required separate (or upsized) neutrals. Instead, he should have cited the specification requirement that had not been met.
 
e57

e57

Senior Member
Location
San Francisco, CA
jerry dutton said:
Where can I find this in the 2008 code book?
Click to expand...
Definitions: page 70-25 for "Branch Circuit, Multiwire".... 210.2 - on page 70-45.... Some other attention should also be brought to light with 310.15(B)2 if they want to 'correct' what they 'think' is 'wrong' with it.... Page 70-145.....
 
ohmhead

ohmhead

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Location
ORLANDO FLA
Well question is there a complete listing of all the 2008 changes for electricians .

To help us find all the changes in the 2008 ?
 
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