Wire Derate in Panduit

Status
Not open for further replies.
D

dasarmin

Member
Location
Texas
Is it required to derate (number of current carryng conductores) wire when installed inside an enclosure and routed in panduit? Or is the "Free Air" ampacity table applicable?
 
Panduit is a very generic term. What code article does the application fall under, and actually, if you know the code article you can find the answer....
 
tom baker said:
Panduit is a very generic term. What code article does the application fall under, and actually, if you know the code article you can find the answer....
Click to expand...

Maybe I should have said Wire Way or Duct, for example Panduit 4 x 5 plastic wire duct w/ cover. For example a VFD Drive Enclosure: a 480V Main Breaker feeds a Distribution Block which then feeds multiple VFDs. The Free Air table would apply to the wire to/from the CB and to the Block; but from the Block the wires will route into wire duct for some distance. Even on the loadside of the VFDs, the wires, too might route in wire duct before landing on terminals, then to the motors.
 
What makes you think that the innards of such a thing would need to comply with the NEC in the first place?

I am not suggesting it does or does not, just asking what legally mandated code says it applies.

Why would anything in the box be considered to be in free air at all? It is inside a box. Hardly in free air.
 
dasarmin said:
Is it required to derate (number of current carryng conductores) wire when installed inside an enclosure and routed in panduit? Or is the "Free Air" ampacity table applicable?
Click to expand...

Are they together for more than 24"?

(3) Adjustment Factors.
(a) More Than Three Current-Carrying Conductors in a
Raceway or Cable.

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). Each current-carrying conductor
of a paralleled set of conductors shall be counted as
a current-carrying conductor.
Where conductors of different systems, as provided in
300.3, are installed in a common raceway or cable, the
adjustment factors shown in Table 310.15(B)(3)(a) shall
apply only to the number of power and lighting conductors
(Articles 210, 215, 220, and 230).
Click to expand...

Panduit is not a raceway so what I made bold applies.

If the NEC does apply to this equipment.
 
Last edited:
petersonra said:
What makes you think that the innards of such a thing would need to comply with the NEC in the first place?

I am not suggesting it does or does not, just asking what legally mandated code says it applies.

Why would anything in the box be considered to be in free air at all? It is inside a box. Hardly in free air.
Click to expand...

I generally use the NEC for most all my wiring, maybe the UL508A would be a better reference to use on interior panel wiring. I consider "Free Air" to be not run in a conduit or raceway (never really sure what a raceway includes). I would consider there to be free air inside an enclosure and individual wires running between terminals or devices to be rated per "free air" ampacity. It?s when these current carrying wires get tie-wrapped together of bundled in wire duct, that I question whether de-rating is needed. I believe this de-rating to be for heat, which could apply in a wire duct or even is large group of wires are tie-wrapped together and sticky-backed to the panel of an enclosure.

None of the (Panduit) wire runs will be (in this case) longer than 24".
 
dasarmin said:
I generally use the NEC for most all my wiring, maybe the UL508A would be a better reference to use on interior panel wiring. I consider "Free Air" to be not run in a conduit or raceway (never really sure what a raceway includes). I would consider there to be free air inside an enclosure and individual wires running between terminals or devices to be rated per "free air" ampacity. It?s when these current carrying wires get tie-wrapped together of bundled in wire duct, that I question whether de-rating is needed. I believe this de-rating to be for heat, which could apply in a wire duct or even is large group of wires are tie-wrapped together and sticky-backed to the panel of an enclosure.

None of the (Panduit) wire runs will be (in this case) longer than 24".
Click to expand...

I don't believe wire duct like what you are describing is a raceway as defined in the code. Article 100 defines what a raceway is.

Are wires in a gutter in free air? They are not usually bundled together yet you cannot use the free air ampacity inside of a gutter.

UL508a has none of the restrictions on bundling of wires, nor does it have any temperature derating requirements. It also restricts itself to 40 deg C maximum ambient temperatures.
 
If it's less then 24" then derating doesn't apply. If more than 24" then iwire gave you the applicable code section. Defining without maintaining spacing within the panduit may be an issue. Also if more than 24" then 310.15(A)(2)Exception may apply.
 
Last edited:
iwire said:
...
Panduit is not a raceway so what I made bold applies.

If the NEC does apply to this equipment.
Click to expand...

I thought that was what that section says too, but CMP6 does not agree.
6-44 Log #3390 NEC-P06 Final Action: Reject
(310.15(B)(3)(a))
________________________________________________________________
Submitter: Donald A. Ganiere, Ottawa, IL
Recommendation: Add new text to read as follows:
(3) Adjustment Factors.
(a) More Than Three Current-Carrying Conductors in a Raceway or Cable.
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). Each current carrying conductor of a paralleled set of conductors shall be counted as a
current-carrying conductor.
Substantiation: Delete ?in a Raceway or Cable?. Those words are in conflict with the wording in the section itself. The section wording makes it clear that a
current adjustment factor is required for three or more current carrying conductors that are installed without maintaining spacing and are not in a
raceway or cable.
Panel Meeting Action: Reject
Panel Statement: Section 310.15(B)(3)(a) is specific to conductors in raceway or cable. This section provides references to other sections, but contains rules
for only conductors in raceways or cables.
Number Eligible to Vote: 10
Ballot Results: Affirmative: 10
Click to expand...
In the post, the words in red are the words my proposal intended to delete.
I have no idea what panel 6 was thinking when they wrote the comment.
 
don_resqcapt19 said:
I thought that was what that section says too, but CMP6 does not agree.

In the post, the words in red are the words my proposal intended to delete.
I have no idea what panel 6 was thinking when they wrote the comment.
Click to expand...

I read your post 3 times and I'm still confused. It's the CMP saying something contradictory to the actual words in that section?
 
http://www.panduit.com/ccurl/88/673/wiring-duct-selection-guide-wdsg01.pdf

Panduit fill tables. At the bottom of the page is some approval and compliance stuff. I do not believe that
Panduit actually IS a raceway per NEC even though it performs that function. This stuff is for control panels.
This would be covered under UL508A. You aren't going to stick it on a wall and pull wire through it. If you have
concerns then use wider and or deeper panduit. Anyhow, awhile ago I asked the same thing to our engineers
because we built a panel with a lot of drives in it. The consensus was to go by the fill tables and not worry about
the NEC in this application other than for wire sizing.
 
infinity said:
I read your post 3 times and I'm still confused. It's the CMP saying something contradictory to the actual words in that section?
Click to expand...

It sounds like they are saying derating does not apply to single conductors not in a raceway. Such as thhn in panduit.

But in my opinion the words in that section say otherwise.
 
iwire said:
It sounds like they are saying derating does not apply to single conductors not in a raceway. Such as thhn in panduit.

But in my opinion the words in that section say otherwise.
Click to expand...

I completely agree the words are right there in that section. Sounds like the CMP didn't peruse Don's proposal.
 
infinity said:
I read your post 3 times and I'm still confused. It's the CMP saying something contradictory to the actual words in that section?
Click to expand...
In my opinion they are very clearly saying that. It was my opinion that the title of the section and the text of the section are in conflict with each other. My proposal would have removed that conflict. The panel statement say that the title of the section is correct and that the text is wrong.
Maybe someone else can take a crack at this for the 2017 code.
 
Aleman said:
http://www.panduit.com/ccurl/88/673/wiring-duct-selection-guide-wdsg01.pdf

Panduit fill tables. At the bottom of the page is some approval and compliance stuff. I do not believe that
Panduit actually IS a raceway per NEC even though it performs that function. This stuff is for control panels.
This would be covered under UL508A. You aren't going to stick it on a wall and pull wire through it. If you have
concerns then use wider and or deeper panduit. Anyhow, awhile ago I asked the same thing to our engineers
because we built a panel with a lot of drives in it. The consensus was to go by the fill tables and not worry about
the NEC in this application other than for wire sizing.
Click to expand...
Often field wires are installed in the panduit in the panel. These conductors are subject to the NEC, even if the internal wiring of the panel is not.
 
don_resqcapt19 said:
Often field wires are installed in the panduit in the panel. These conductors are subject to the NEC, even if the internal wiring of the panel is not.
Click to expand...


Well I will assume in that case that the manufacturers specs for the raceway would count for fill. Panduit isn't covered by the NEC but it is UL listed
and by the NFPA and others.
But you are right, field wiring is shared by both. I would say that once it enters the panel, then panel rules will apply. Once the field wiring is in the panel
then it also leaves the original raceway. It's a whole new deal subject to whatever parts the panel is built with.
 
Aleman said:
Well I will assume in that case that the manufacturers specs for the raceway would count for fill. Panduit isn't covered by the NEC but it is UL listed
and by the NFPA and others.
But you are right, field wiring is shared by both. I would say that once it enters the panel, then panel rules will apply. Once the field wiring is in the panel
then it also leaves the original raceway. It's a whole new deal subject to whatever parts the panel is built with.
Click to expand...

I don't agree. The NEC applies to the field wiring in the panel. That wiring is not subject to the rules that applied to the construction of the panel. The field wiring is subject to the rules in the NEC.
 
Status
Not open for further replies.
Top