derating service entrance conductors??

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jotw

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New user. I tried to post this earlier. Don't know what I did wrong. Anyway. I just designed my first 3 phase service. I derated the SECs for the neutral (4th CCC). My employer is telling me that I didn't have to derate conductors in a service riser. I've looked all through 2008NEC and cannot find anything to substantiate his claim. Can/will anyone point me in the right direction? That is, if I was wrong to begin with. ???
 
CCC derating starts at 4 conductors [T310.15(B)(2)(a)]. . Many times you don't have to count the neutral as a CCC, see 310.15(B)(4).
 
In general, it's better/safer/easier to just consider the neutral a CCC.

I can't think of how the conductors being service conductors would tie into the decision to count the neutral as a CCC or not.
 
George Stolz said:
In general, it's better/safer/easier to just consider the neutral a CCC.
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I would never consider the neutral of a service as a CCC.

The only way the NEC would require us to is if the major portion of the load was non-linear and it would have to be an odd building for that to be the case for the service conductors. :smile:
 
iwire said:
I would never consider the neutral of a service as a CCC.

The only way the NEC would require us to is if the major portion of the load was non-linear and it would have to be an odd building for that to be the case for the service conductors. :smile:
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Agreed. There are almost no services that would have a greater than 50% harmonic load on the neutral.
 
iwire said:
. . . If your talking a data center the HVAC load should be keeping up with the electronic load.
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Yes I am and I think I am forced to agree with you.
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Thanks dnem. Again, the answer was right in front of me, and I skipped right over it. It all starts to get blurry after about 7 (p.m.).
 
Because it's more conservative to consider it a CCC in the field. There is no more restrictive view, therefore an inspector or anyone else can't come along and call it a CCC without me still being in compliance.

As far as test taking goes, I'd likely have a different answer.
 
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