Conduit fill

[easymoney]

When calculating conduit fill, Do you count the neutral as a current carrying conductor?

 

[augie47]

seems a mismatch of terms. when figuring conduit fill, you count every conductor. when de-rating conductor ampacity based on the number of conductors in the conduit, you ascertain if the neutral is a ccc by the rules in 310.15, Note 4.

 

[easymoney]

In the heading of the annex it says number of current carrying conductors in rmc. does the number they give include the grouned conductor?

 

[augie47]

can you refer me to a page number ? (70-***)
I see no where in the annex where it states number of current carrying conductors.

 

[480sparky]

Raceway fill is a simple mathematical problem: How many little circles can you put inside a big circle?

"Current carrying conductors" is another beast entirely. The word "current" does not appear in Annex C at all.

 

[Dennis Alwon]

In the heading of the annex it says number of current carrying conductors in rmc. does the number they give include the grouned conductor?

Yes you include both the neutral and ground wire in your conduit fill.

As others have said the only time a neutral may not count is for derating purposes not conduit fill.

 

[kwired]

Raceway fill is a simple mathematical problem: How many little circles can you put inside a big circle?

"Current carrying conductors" is another beast entirely. The word "current" does not appear in Annex C at all.

Anncurrentex C

now it does

 

[easymoney]

That is my fault, Not annex c I ment to say table B.310.11

In tabble B.310.11 do you count the grounded conductor ( or common inD/C) as number of current carrying conductors

 

[Dennis Alwon]

That is my fault, Not annex c I ment to say table B.310.11

In tabble B.310.11 do you count the grounded conductor ( or common inD/C) as number of current carrying conductors

I don't see that Table in Annex B, however I may have what you want

310.15(B)(4) Neutral Conductor.
(a) A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(B)(2)(a).
(b) In a 3-wire circuit consisting of two phase conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system, a common conductor carries approximately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying the provisions of 310.15(B)(2)(a).
(c) On a 4-wire, 3-phase wye circuit where the major portion of the load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor.

 

[easymoney]

That is exactly what I was looking for, Thanks

The table I was talking about is B.310.11 Adjustment factors for more than 3 current-caryying conductors in a raceway

 

[david luchini]

I don't see that Table in Annex B, however I may have what you want

Dennis, look at the last page of Annex B. It's basically the same as table 310.15(B)(2)(a), but it adds "load diversity" into the mix. So your reference to 310.15(B)(4) is spot-on.

 

[Dennis Alwon]

Thanks David. I totally missed that Table somehow but I don't believe we, as electricians, can use Annex B unless under engineering supervision.

B.310.15(B)(1) Formula Application Information.
This annex provides application information for ampacities calculated under engineering supervision.