Derating 34 currrent carrying conductors into a metallic auxiliary gutter....

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CelsoSr

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How do I apply adjustment factors of 310.15(B)(2)(a). Taking in account the four conductors over 30 (80%), or all of them (40%) and apllying to the 34 ccc?
 
Welcome to the forum.:)

You would need to take all of them into account not just the 4 over 30 that you have.

So for 34 CCC's you would need to adjust the ampacity by 40%.

Chris
 
Dennis Alwon said:
Where is there an allowance for that. I am assuming you mean the divider changes the derating.
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I have used trough ends as dividers and do not believe I need an allowance for it.


376.22 Number of Conductors and Ampacity. The number
of conductors and their ampacity shall comply with
376.22(A) and (B).


(B) Adjustment Factors. The adjustment factors in
310.15(B)(2)(a) shall be applied only where the number of
current-carrying conductors, including neutral conductors
classified as current-carrying under the provisions of
310.15(B)(4), exceeds 30. Conductors for signaling circuits
or controller conductors between a motor and its starter and
used only for starting duty shall not be considered as
current-carrying conductors.
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I still don't see where the divider allows you to have more than 30 conductors without derating. I think it makes sense but I don't see the wording.
 
Dennis Alwon said:
I still don't see where the divider allows you to have more than 30 conductors without derating. I think it makes sense but I don't see the wording.
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"Only where" if you have a wireway with 40 conductors and you place a divider in the right spot you would not have any 'where' with more than 30 conductors. I see no ambiguity or gray area.
 
iwire said:
"Only where" if you have a wireway with 40 conductors and you place a divider in the right spot you would not have any 'where' with more than 30 conductors. I see no ambiguity or gray area.
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I am having a hard time seeing how this incomplete raceway divider thing gets you out of derating.

The "only where" part seems to apply to the more than 30 ccc's that are installed in a section. Only the wires that pass through that particular section.

An incomplete divider does not seem to make 2 sections of raceway out of one.
 
Thanks...

Thanks...

Thanks to all of you for your answers. Very interesting and clever...but looks odd for me to get 40% for 4 more conductors and 100% for 30!
 
CelsoSr said:
Thanks to all of you for your answers. Very interesting and clever...but looks odd for me to get 40% for 4 more conductors and 100% for 30!
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I know, but that is where the CMP drew the line in the sand.
 
jumper said:
I am having a hard time seeing how this incomplete raceway divider thing gets you out of derating.
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An incomplete divider does not seem to make 2 sections of raceway out of one.
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Incomplete?

Who said it was incomplete?

If I have a 12" x 12" wireway and install a 12" x 12" blank end fitting in the middle it is about as a complete a divider as you can have.:)
 
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