De-rating wire in Wireduct

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Hello,

I have a question that I can't find the answer to, when running wires in Panduit wireduct (which clearly breathes/ is ventilated) do you have to de-rate the wires if the qty of wires in the panduit is over 3?

Thanks,
 

ActionDave

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Look at Art. 310-

TABLE 310.15(B)( 3)(a) Adjustment Factors for More Than
Three Current-Carrying Conductors in a Raceway or Cable
Now look at the Art 100 definition of Raceway-

Raceway. An enclosed channel of metal or nonmetallic
materials designed expressly for holding wires, cables, or
busbars, with additional functions as permitted in this Code.
Raceways include, but are not limited to, rigid metal con-
duit, rigid nonmetallic conduit, intermediate metal conduit,
liquidtight flexible conduit, flexible metallic tubing, flexible
metal conduit, electrical nonmetallic tubing, electrical me-
tallic tubing, underfloor raceways, cellular concrete floor
raceways, cellular metal floor raceways, surface raceways,
wireways, and busways.
 

infinity

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IMO this is not a raceway but derating my need to be applied if you think that the cables are bundled for more than 24". In many cases 310.15(A)(2)Ex. would eliminate the need to derate a 3' section of wire duct.

Panduit-DFductLG-72-image1.jpg
 

kwired

Electron manager
Location
NE Nebraska
But the wiring duct in the picture is most often used inside industrial control panels, not as a raceway in buildings

Good point. Also one may ask just how many conductors in that duct may possibly need ampacity adjustments if you want to be strict with the 24 inch bundling rule? Many conductors in there may be control conductors that typically don't get counted as current carrying conductors for ampacity correction purposes.
 
Thanks for all the replies guys, I'm still a little unsure of this, but there may not be a direct answer. My question was only speaking of the case with industrial control panels as mentioned. But I was not only asking about a PLC like cabinet, but also a motor control cabinet, which would have 480V power wiring.

Thanks again to all that contributed!
 

Smart $

Esteemed Member
Location
Ohio
Thanks for all the replies guys, I'm still a little unsure of this, but there may not be a direct answer. My question was only speaking of the case with industrial control panels as mentioned. But I was not only asking about a PLC like cabinet, but also a motor control cabinet, which would have 480V power wiring.

Thanks again to all that contributed!
The NEC does not specify the ampacity of conductors inside a cabinet, enclosure, box, etc. How can you derate it if it doesn't have an ampacity to begin with???
 

don_resqcapt19

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The NEC does not specify the ampacity of conductors inside a cabinet, enclosure, box, etc. How can you derate it if it doesn't have an ampacity to begin with???
The NEC applies to the field installed conductors that connect to the equipment within the panel. It is common to see industrial control panels with multiple IEC starters and or VFDs where the conductors to the motors in the field are run in wireway within the panel and then leave the panel via multiple conduits.
 

kwired

Electron manager
Location
NE Nebraska
The NEC does not specify the ampacity of conductors inside a cabinet, enclosure, box, etc. How can you derate it if it doesn't have an ampacity to begin with???
So if I had a breaker and motor contactor in same cabinet for a motor that has FLA of 60 amps I could run 14 AWG conductors between the two devices and not be a NEC violation:cool:

Or is it just that I don't have to deal with ampacity adjustments within the cabinet?
 

petersonra

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Northern illinois
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engineer
So if I had a breaker and motor contactor in same cabinet for a motor that has FLA of 60 amps I could run 14 AWG conductors between the two devices and not be a NEC violation:cool:

Or is it just that I don't have to deal with ampacity adjustments within the cabinet?

there are no ampacity adjustments required for number of conductors in the enclosure.
 

Smart $

Esteemed Member
Location
Ohio
...derating my need to be applied if you think that the cables are bundled for more than 24"...

Unless they are bundled longer than 24".
Applies to cables, including single-conductor cables... but not single conductors.

Additionally, that's a requirements under 310.15(B) Tables, which are enumerated thereunder. What table listed applies to conductors in enclosures, cabinets, boxes, etc.?
 

Smart $

Esteemed Member
Location
Ohio
The NEC applies to the field installed conductors that connect to the equipment within the panel. It is common to see industrial control panels with multiple IEC starters and or VFDs where the conductors to the motors in the field are run in wireway within the panel and then leave the panel via multiple conduits.
That is correct... but the NEC does not mandate any 'derating' for conductors inside an enclosure, cabinet, box, etc. Derating is completely based on the conditions of installation exterior to such.
 

don_resqcapt19

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retired electrician
That is correct... but the NEC does not mandate any 'derating' for conductors inside an enclosure, cabinet, box, etc. Derating is completely based on the conditions of installation exterior to such.
I don't read the section that way. What in the following section says you don't derate for"bundled" conductors within an enclosure or cabinet?
(3) Adjustment Factors.
(a) More Than Three Current-Carrying Conductors.
Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(3)(a). ...
 

iwire

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Staff member
Location
Massachusetts
Applies to cables, including single-conductor cables... but not single conductors.

Additionally, that's a requirements under 310.15(B) Tables, which are enumerated thereunder. What table listed applies to conductors in enclosures, cabinets, boxes, etc.?

I see nothing excluding single conductors in enclosures.

And considering the physics don't change it makes sense.
 

Smart $

Esteemed Member
Location
Ohio
I don't read the section that way. What in the following section says you don't derate for"bundled" conductors within an enclosure or cabinet?
That's 310.15(B)(3)(a)...

310.15(B) is titled Tables and the general statement immediately thereafter states which tables are to be used. The allowable ampacity Table's heading states the condition of installation. Which Table provides the allowable ampacity of single conductors where installed in an enclosure, cabinet, box, etc.?

The conductors aren't in raceway or cable or in earth [Table 310.15(B)(16)]. Should I use "Free Air" [Table 310.15(B)(17)]?

If we are to extend the conditions of installation from outside the enclosure, cabinet, etc. into the same (to determine which table to use), where does Code say to do that?
 

iwire

Moderator
Staff member
Location
Massachusetts
T. Which Table provides the allowable ampacity of single conductors where installed in an enclosure, cabinet, box, etc.?

The conductors aren't in raceway or cable or in earth [Table 310.15(B)(16)]. Should I use "Free Air" [Table 310.15(B)(17)]?

So you are saying there are no NEC ampacities for inside enclosures?
 
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