300.20(A) Ferrous Enclosures

infinity

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New Jersey
Having a discussion the other day about running conductors together in metal enclosures such as switchboards or in this case large fuse cabinets. For ease of installation and aesthetics the installer of these conductors (not me) grouped them by phase and neutral as they entered the box on top and then terminated them to their appropriate terminals. Some discussion ensued about whether or not this violated 300.20(A) which requires some sort of grouping, however the term grouped together is undefined so is this a violation or isn't it?

300.20 Induced Currents in Ferrous Metal Enclosures or Ferrous Metal Raceways.
(A) Conductors Grouped Together. Where conductors carrying alternating current are installed in ferrous metal enclosures or ferrous metal raceways, they shall be arranged so as to avoid heating the surrounding ferrous metal by induction. To accomplish this, all phase conductors and, where used, the grounded conductor and all equipment grounding conductors shall be grouped together.

 
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Dennis Alwon

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Chapel Hill, NC
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Electrical Contractor
That's a good question. Part of me feels they are grouped together just by being in the enclosure but why have that article if this is not a violation. What percentage of the run in the enclosure needs to be grouped because at some point they cannot be grouped together? (Rhetorical Question):?
 

infinity

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Location
New Jersey
I have no idea what the definition of grouped together is in this application. I agree with Dennis that they're grouped by virtue of their proximity to each other but some others involved in the discussion had different opinions. My argument was that bus bar in switchgear (or even in this fuse cabinet) is typically spaced several inches apart which in effect means that they're grouped.

For what it's worth grouping the phase and neutrals together in this fashion (in the photos) has been the SOP for decades so I'm wondering why it suddenly may be a problem.
 

Little Bill

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Location
Tennessee NEC:2017
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Electrician
Having a discussion the other day about running condcutors together in metal enclosures such as switchboards or in this case large fuse cabinets. For ease of installation and aesthetics the installer of these conductors (not me) grouped them by phase and neutral as they entered the box on top and then terminated them to their appropriate terminals. Some discussion ensued about whether or not this violated 300.20(A) which requires some sort of grouping, however the term grouped together is undefined so is this a violation or isn't it?
Don't know what "condcutors" are, they may get hotter.:D

IMHO this rule is intended for raceways and metal enclosures that the conductors run through because as said, the conductors have to be separated where they terminate anyway. Your pics didn't show whether the conduit was metal or PVC. If metal, I would say that if the conductors are grouped as they are in the cabinet, then that is a violation.
 

Ragin Cajun

Senior Member
Location
Upstate S.C.
Perhhaps to put it another way; phases a, b, c, and the neutral MUST run "together" in the same conduit and penetrate the enclosure in the same way. Otherwise, you will have serious induction heating!

RC
 

jusme123

Senior Member
Location
NY
IMO it is not a violation. When most electricians terminate a panel, the first thing terminated are the neutrals and the grounds, and they both are grouped. The question remains, how far can the conductors be grouped before considering it a violation. My opinion is as soon as they enter the enclosure they can be grouped.
 

jim dungar

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Staff member
Location
Wisconsin
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Engineer
I would worry more about the short circuit forces than the inductive heating.
These conductors may not be laced and braced enough.
 

texie

Senior Member
I would worry more about the short circuit forces than the inductive heating.
These conductors may not be laced and braced enough.
I was sort of thinking the same thing when I saw this. But other than that, it sure looks real nice. I can't believe it has taken us all these years for large size conductors in colors to become common place. I guess Southwire gets the credit.
 
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