300.20 Gone Wild

wwhitney

Senior Member
Location
Berkeley, CA
So "to accomplish this" is a modifier that limits the grouping requirement to the locations where grouping is necessary to "avoid heating the surrounding ferrous metal".

Cheers, Wayne
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I recently had someone tell me that they've been told that it's an NEC requirement to keep the conductors of a multi-conductor cable (like MC) twisted together within a panel because of 300.20. Please stop the insanity. BTW I hate the wording of this section. :eek:hmy:

Has anyone else heard of people enforcing this?
The way I see it is, if the NEC actually wanted conductors twisted together in a panelboard or load center they would have specifically stated "twisted" as they have in 410.54(C)

(C) Twisted or Cabled.

Pendant conductors longer than 900 mm (3 ft) shall be twisted together where not cabled in a listed assembly.


If CMP 3 didn't know how to spell "twisted" they could have gotten help from CMP 18.

Roger


 

iwire

Moderator
Staff member
Location
Massachusetts
I have been reading along and honestly if an inspector hit me with this idea on a job I have no doubt I would end up laughing out loud and ignoring them about it. Seriously, I am up for trying most anything but I am not going to wast time trying to do the impossible.

Neutral bar on the top right, EGC bar on the top left and the hot going to breaker 42. How could you keep that grouped together beyond all being in the enclosure as Charlie and Al have mentioned?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
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
They should not have added the words that I show in bold, but I don't see any way that those words do not require that the conductors be grouped together within an enclosure.
 

mivey

Senior Member
They should not have added the words that I show in bold, but I don't see any way that those words do not require that the conductors be grouped together within an enclosure.
Given iwire's post #24 that is one of the most rediculous things I have ever heard you say and I have tremendous respect for you. How can this be?
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
They should not have added the words that I show in bold, but I don't see any way that those words do not require that the conductors be grouped together within an enclosure.
And if they are in the same enclosure they are grouped. Nowhere in the common understanding of the word grouped, or in the electrical understanding, is there any implication that the conductors have to be touching each other.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
This code section needs to be revised. :slaphead:
No it doesn't. A few dunke-offs in NJ may need a forceful talking to, but the rest of the world is getting along just fine. Not just NJ actually, there is always an inspector or code instructor out there somewhere that wants to stroke his ego by coming up with the secret message in the NEC that no one else knows about.
 

Strathead

Senior Member
They should not have added the words that I show in bold, but I don't see any way that those words do not require that the conductors be grouped together within an enclosure.
Well it is an issue of what "grouped" means. Inside a panel where it is physically impossible to keep them in close proximity it is obvious to the thinking person that they don't mean kept tightly together. I would be far more concerned with a niggling interpretation in a gutter for example. Common sense tells me that as long as the outgoing and return conductors for a current path are not separated by metal, then it would take extraordinary circumstances like very high frequency to cause heating of surrounding metal. I guess if an inspector actually tried to force you to bundle them together, you could just get a cheap IR gun and prove that the surrounding metal isn't getting hot. That would "prove" that the "grouping" was sufficient.
 

mgookin

Senior Member
Location
Fort Myers, FL
The consensus here seems to be that "grouped" means physically present in the same pipe, disconnect or panel. It does not mean twisted or touching.

As someone pointed out, you can have 20 third graders in a classroom. They are grouped. They don't have to be touching, twisted together or anything other than present in the same space.

The intent of the code is to prevent undue heat. Having your hots & neutrals in the same pipe, disco or panel accomplishes that. The code is complied with the way it's always been done. There is no need for outrageous interpretations.

The code even defines the space as " ferrous metal enclosures or ferrous metal raceways".
 

jaggedben

Senior Member
No it doesn't. A few dunke-offs in NJ may need a forceful talking to, but the rest of the world is getting along just fine.
I dispute that. I'm not getting along fine with a number of inspectors who've required me to run a neutral with a switch leg to a disconnect, for absolutely no good reason. We've lost hundreds of dollars to additional labor and reinspection fees. Unfortunately NJ has no monopoly on "dunke-offs."

I know, not the same issue as what's already been discussed in this thread, but still the same basic problem: inspectors are not physicists, shouldn't be expected to be, and need the code written clearly enough to provide reasonable enforcement without so being.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
Common sense tells me that as long as the outgoing and return conductors for a current
path are not separated by metal, then it would take extraordinary circumstances like very
high frequency to cause heating of surrounding metal.

I guess if an inspector actually tried to force you to bundle them together, you could just
get a cheap IR gun and prove that the surrounding metal isn't getting hot. That would
"prove" that the "grouping" was sufficient.
thank you. and as long as they don't take divergent paths, they are grouped.

if we are going to start this batchit crazy theory that the wires need to be
twisted inside a ferrous metal enclosure, then we'd better get started repulling
all of north america, as i suspect there are feeders laying parallel inside ferrous
conduits, that are about to burst into flame. the heat from all those straight
and narrow conductors is the real cause of global warming.
 

charlie b

Moderator
Staff member
Location
Seattle, WA
They should not have added the words that I show in bold, but I don't see any way that those words do not require that the conductors be grouped together within an enclosure.
Given iwire's post #24 that is one of the most rediculous things I have ever heard you say and I have tremendous respect for you. How can this be?
I also have respect for Don, and I agree with what Don said: the conductors do have to be grouped within an enclosure. At issue is the meaning of "grouped." As others have also said, I don't interpret "grouped" as meaning "touching or twisted together." I say they are "grouped" if they enter the enclosure from the same conduit, and either they are terminated within the enclosure or they exit the enclosure within the same conduit.

 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
I dispute that. I'm not getting along fine with a number of inspectors who've required me to run a neutral with a switch leg to a disconnect, for absolutely no good reason. We've lost hundreds of dollars to additional labor and reinspection fees. Unfortunately NJ has no monopoly on "dunke-offs." ..........
You quoted the first half of what I said, that had to do with this thread topic. I addressed your situation in the second half.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
I dispute that. I'm not getting along fine with a number of inspectors who've required me to run a neutral with a switch leg to a disconnect, for absolutely no good reason. We've lost hundreds of dollars to additional labor and reinspection fees. Unfortunately NJ has no monopoly on "dunke-offs."

I know, not the same issue as what's already been discussed in this thread, but still the same basic problem: inspectors are not physicists, shouldn't be expected to be, and need the code written clearly enough to provide reasonable enforcement without so being.
the problem is, it's not about interpreting the code.

it's about someone seeing how far they can pee, intellectually.
and about the exercise of power.
 

charlie b

Moderator
Staff member
Location
Seattle, WA
A few dunke-offs in NJ may need a forceful talking to. . . .
I started to laugh when I saw that word. I presumed that it was an intentional play on sounds. For those who don't get the joke, the correct spelling of the German word is "dummkopf," and it roughly translates to a stupid person, a blockhead. It is pronouced pretty much like "dumke-off," if you pronounce the "u" like the "u" in "duel." That, at least, is what little I remember of the three years that I studied German, a time period that ended in third grade. Don't ask me how long ago that was. :lol:

 

iwire

Moderator
Staff member
Location
Massachusetts
I dispute that. I'm not getting along fine with a number of inspectors who've required me to run a neutral with a switch leg to a disconnect, for absolutely no good reason. We've lost hundreds of dollars to additional labor and reinspection fees. Unfortunately NJ has no monopoly on "dunke-offs."

I know, not the same issue as what's already been discussed in this thread, but still the same basic problem: inspectors are not physicists, shouldn't be expected to be, and need the code written clearly enough to provide reasonable enforcement without so being.
Than try to write it. I am not busting chops but write it how you think it is clear and then let us pick it apart.

I think you will find it is not easy to write, clear, concise, to the point, 'one rule fits all installations' code sections.
 
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