300.20 Gone Wild

jaggedben

Senior Member
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.
That's totally fair, and I have actually given it some thought, although I've not gotten as far as drafting text. I do agree with your last sentence. Maybe I'll get back to you when it's the weekend and not my lunch break. :D

Probably one way to keep it concise is to refer to the switch leg rules in chapter 4.
 

jaggedben

Senior Member
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.
Well, yeah. You sort of contradicted yourself there. Everyone's getting along fine, except for those unreasonable inspectors messing with us all the time. :lol:
 

kwired

Electron manager
Location
NE Nebraska
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.
Bingo - 2

If they were good at what they do they look into things and try to learn when they run into something new instead of seeing how far they can pee:roll:
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
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.

And I don't see them as grouped, if one conductor runs down on side of the panel and other conductors of the same circuit run down the other side of the panel.
There is no good reason for the last sentence of the code section and it should just be deleted.
 

iwire

Moderator
Staff member
Location
Massachusetts
And I don't see them as grouped, if one conductor runs down on side of the panel and other conductors of the same circuit run down the other side of the panel.
Yet they are grouped in the same panel as opposed to some outside the panel and some inside. How close together would they have to be for you to consider them grouped?
 

Smart $

Esteemed Member
Location
Ohio
Used to watch it with my Dad in the evening. It was good times but what an odd concept for a show with a laugh track. :dunce:
Odd concept, perhaps. But it was entertaining enough to carry the show for six seasons. :thumbsup:
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
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.
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
And I don't see them as grouped, if one conductor runs down on side of the panel and other conductors of the same circuit run down the other side of the panel.
As close as NM has to be before you call it grouped for derating purposes:D
The following is from the NFPA Glossary of Terms.
Grouped. Cables or conductors positioned adjacent to one another but not in continuous contact with each other.
Thank you Don. I've been away for a bit. This helps me understand a bit better.

Here, try this one:

NFPA Glossary of Terms
Adjacent.
Sharing a common wall, partition, or barrier.
For the purposes of the 300.20 ferrous metal raceways and/or enclosures, there is no "partition", and the "common wall" or "barrier" IS the ferrous metal of the raceway or enclosure.

That is, the conductors are adjacent by sharing the common walls of the enclosure (or raceway).
 

Smart $

Esteemed Member
Location
Ohio
...
Here, try this one:

NFPA Glossary of Terms
Adjacent.
Sharing a common wall, partition, or barrier.
For the purposes of the 300.20 ferrous metal raceways and/or enclosures, there is no "partition", and the "common wall" or "barrier" IS the ferrous metal of the raceway or enclosure.

That is, the conductors are adjacent by sharing the common walls of the enclosure (or raceway).
That's one interpretation.

Could be construed as a conductor and/or its insulation as being the common partition or barrier. And that is the problem as presented.
 

romex jockey

Senior Member
Location
Vermont
But it remains no more than objective interpretation w/o quantifying it all....

And that would require a measurement juxtaposed to the physical wear on any given conductor(s)

Hypothetically , let's say they place a gauss level upon 300.20 .

I'm sure we'd all be good with grouping against such a figure in our panels

But we'd quickly realize that the Xformer right next to said panel is actually the biggest culprit. (It's not hot because it's mad at you)

Which short of some auto xformer manufacturer magic, isn't going to meet the same parameters you're breaking a bead arranging your panel for....

Next would be the realization that M.E.N. mentality essentially proliferates gauss through out an entire structure.....


the horror!.....:)

Perhaps some Gauss Fault Interrupter will save us all?

~RJ~
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Thank you Don. I've been away for a bit. This helps me understand a bit better.

Here, try this one:
NFPA Glossary of Terms
Adjacent.
Sharing a common wall, partition, or barrier.
For the purposes of the 300.20 ferrous metal raceways and/or enclosures, there is no "partition", and the "common wall" or "barrier" IS the ferrous metal of the raceway or enclosure.

That is, the conductors are adjacent by sharing the common walls of the enclosure (or raceway).
You also have to look at the 3 right hand columns in the glossary....the document that "adjacent" applies to is NFPA 820, while the document that "grouped" applies to is NFPA 70
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
...
Hypothetically , let's say they place a gauss level upon 300.20 . ... ~RJ~
300.20 is also an issue....the equivalent rule in the Canadian Electrical Code does not apply under 200 amps. There is just not enough inductive heating at the lower current levels for this to be a real issue.
 

iwire

Moderator
Staff member
Location
Massachusetts
Don you are tossing aside basic commonsense in this thread.

Do you really think the CMP that put that rule in place was so removed from the trade they asked for the impossible?


I find the whole notion just silly.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
You also have to look at the 3 right hand columns in the glossary....the document that "adjacent" applies to is NFPA 820, while the document that "grouped" applies to is NFPA 70
OK. If the NFPA Glossary definition only applies to 820, then, we are left with "adjacent" as a "general" term that the NEC has a clear statement about. From the Scope of Article 100 Definitions:
Article 100 Definitions.

Scope. This article contains only those definitions essential to the proper application of this Code. It is not intended to include commonly defined general terms or commonly defined technical terms from related codes and standards.
Therefore, we turn to Miriam Webster:
Simple Definition of adjacent
1 : close or near : sharing a border, wall, or point

Full Definition of adjacent



  • [*=1]
    a : not distant : nearby <the city and adjacent suburbs>​
b : having a common endpoint or border <adjacent lots> <adjacent sides of a triangle>​
c : immediately preceding or following​
2 : of two angles : having the vertex and one side in common​
So, Don, this brings us back to "conductors shall be grouped together." Your citation of the NFPA Glossary term "grouped" says the conductors are "adjacent" "BUT NOT in continuous contact." The NFPA is deliberately saying, IMO, that Adjacent does not include the conductors being twisted or otherwise forced into intimate contact so as to be touching each other along their entire length . . . The "grouped" conductors need only be close or near, sharing a common border, a border that is the ferrous metal enclosure.

Two neighbors are "adjacent neighbors" if their properties share a property line. The neighbors can be inside their respective houses, yet still be adjacent to each other, without holding hands or otherwise physically touching each other's bodies. The adjacent neighbors are "adjacent" by virtue of being within a common border, the border of their combined two properties.
 
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