2014 nec code to 250.122

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iwire said:
But it won't apply to a fire pump where voltage drop compensation is NEC required
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That's what I was getting at in post #14. Does this really need to be this convoluted?

So if derating requires a larger phase conductor I can still use the smaller EGC but if I happen to have extra conductors laying around that are larger than the circuit requires I need to make sure that the EGC is proportionally increased. :slaphead:
 
Smart $ said:
Correct. A code forced upsizing of ungrounded conductors does not require the EGC to be upsized... but not limited to just under 2014... essentially all editions back to 1999 (or 2002 ?)
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I disagree for the several editions prior to the 2014 where the words simply stated "Where ungrounded conductors are
increased in size". Using #10's on a 20 amp circuit would be an increase in size requiring a #10 EGC as well.


2008 NEC:

250.122(B) Increased in Size. Where ungrounded conductors are
increased in size, equipment grounding conductors, where
installed, shall be increased in size proportionately accord-
ing to the circular mil area of the ungrounded conductors.
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Smart $ said:
Now I'm rethinking that position...
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Don't screw things up, we were making progress. :p


It may apply. The wording refers to minimum ampacity... not minimum code required size.
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Call me doubtful they put that much thought into it.

That makes the whole issue a conundrum without resolution.
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Stay tuned for the next episode in 2017, the CMP needs to leave cliff hangers so we will buy the next book. :D
 
infinity said:
I disagree for the several editions prior to the 2014 where the words simply stated "Where ungrounded conductors are
increased in size". Using #10's on a 20 amp circuit would be an increase in size requiring a #10 EGC as well.


2008 NEC:
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If you take the wording literally, yes.

However if you look up the 2014 proposals and comments you see that the change was to reflect the intent since it was change back in '99 or '02.

I still feel the biggest error in the change back then was to eliminate the "where a wire-type EGC is required". Since then, we have been 'penalized' for running redundant EGC's.

Any word on when comments on inputs will be starting for the 2017 cycle. We all need to gang up on the comments and get this issue straightened out!!!
 
Here's the original 1974 Technical Committee Reports version...

250-955. Size of Equipment Grounding Conductors. The size of copper,aluminum, or copper-clad aluminum equipment grounding conductors
shall not be less than given in Table 250-95.

Where conductors are run in parallel in multiple raceways, as permitted
in Section 310-4, the equipment groundihg conductor, where
used, shall be run in parallel. Each parallel equipment grounding conductor
shall be sized on the basis of the ampere rating of the overcurrent
device protecting the circuit conductors in the raceway in accordance
with Table 250-95.

When conductors are adjusted in size to compensate for voltage drop,
grounding conductors, where required, shall be adjusted proportionately
in size.
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By 1999 edition, moved to 250.122 and changed the "where required" to "where installed".

(b) Adjustment for Voltage Drop. Where conductors are
adjusted in size to compensate for voltage drop, equipment
grounding conductors, where installed, shall be adjusted pro-
portionately according to circular mil area.
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In 2002 changed to "any reason"...

(B) Increased in Size. Where ungrounded conductors are
increased in size, equipment grounding conductors, where
installed, shall be increased in size proportionately accord-
ing to circular mil area of the ungrounded conductors.
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iwire said:
Don't screw things up, we were making progress. :p




Call me doubtful they put that much thought into it.



Stay tuned for the next episode in 2017, the CMP needs to leave cliff hangers so we will buy the next book. :D
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:rotflmao:
 
infinity said:
I disagree for the several editions prior to the 2014 where the words simply stated "Where ungrounded conductors are
increased in size". Using #10's on a 20 amp circuit would be an increase in size requiring a #10 EGC as well.
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And I disagree right back at you. :happyyes:


The problem I have had all along is that the notion of "where . . . conductors are increased in size" never had any meaning. That is, I can't tell whether something was increased, unless I know what it was before it got increased. I have long felt that the "increased in size" needed a few extra words to answer the inherent question, "increased from what?" The 2014 version finally answered that question, and I believe it is the same answer they would have given long ago.

Let's talk about a specific example. Suppose I wish to put five single-phase (2-wire) circuits in the same conduit, and I also wish to use a 20 amp breaker on each circuit. In this scenario, I can't use #12's, period! Going to 10's is not upsizing, it is selecting a size that has sufficient ampacity under the conditions of installation. So I submit that we never had to upsize the EGC to # 10 in this scenario. I acknowledge that I would likely have lost the argument with many an AHJ. But now that argument won't happen, because the 2014 now makes it clear that we don't need a # 10 EGC for this scenario.
 
I have no doubt about that Bob. And indeed I have never designed a circuit with a 20 amp breaker, with an ungrounded wire larger than #12, and with a #12 EGC. In the future, I may or may not use a #12 EGC in the example I presented. I am aware that there is a price for proving you are right, and there is an advantage in giving the AHJ what they want even if I am right.
 
could it be that if your ungrounded conductors are increased in size for voltage drop then the ground should be increased because if the length is that long the resistance is increased in the egc. And if you increased the size due to derating for conduit fill the insulation properties of the ground would not be sufficient and could fail under fault causing damage to the other conductors in the conduit. Im just asking I read the section over and over in the handbook and really don't see a real answer for the requirement. Just an idea didn't mean to start a bash or stir the pot. You guys know better on the subject Im sure.

Thanx
 
Table 250.122 should be reworked so that the size of the EGC is based on the size of the ungrounded conductor and not on the rating of the OCPD. All of this goes away if you do that. Especially the crazy part where a #6 on a 20 amp breaker requires a #6 EGC and that same #6 on a 60 amp breaker only requires a #10 EGC.
 
don_resqcapt19 said:
Table 250.122 should be reworked so that the size of the EGC is based on the size of the ungrounded conductor and not on the rating of the OCPD. All of this goes away if you do that. Especially the crazy part where a #6 on a 20 amp breaker requires a #6 EGC and that same #6 on a 60 amp breaker only requires a #10 EGC.
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That has been my biggest problem with it since they tried to address the issue - and I have always brought up that same example when this topic is brought up.
 
I have a question

I have a question

I've seen contractors run all number 10 hr.from the panel to a trough 10 feet outside the electrical room than change to 12 wire from there .

this has always bothered me ,should it
 
L8TRG8TR said:
I've seen contractors run all number 10 hr.from the panel to a trough 10 feet outside the electrical room than change to 12 wire from there .

this has always bothered me ,should it
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sounds like they possibly needed to adjust ampacity for the first part of the run because of number of current carrying conductors.
 
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