Increase in size

hhsting

Senior Member
I have branch circuit fed from 150A breaker to chiller rooftop. The circuit conductors go on roof so their is rooftop correction and temperature correction factor. The size of phase and neutral conductors are increased from 1/0AWG to 2/0 AWG.

My feelings say equipment grounding conductor which is wire should be increased however reading the handbook blue comments NEC 2014 Section 250.122(B) says in some cases, use of conductors with higher insulation temperature rating allows for compliance with
ampacity adjustment and correction requirements without having to increase the circular mil area of the conductor.


So I am confused should the EGC be increased in scenario first paragraph per NEC 2014 section 250.122(B) or it can be compliance without increase EGC size per NEC 2024 section 250.122(B)?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
 

hhsting

Senior Member
Ok so in my case I am increasing conductor size because of temperature correction factor and rooftop correction factor has nothing to do with insulation then I would need to increase the EGC based on 250.122(B)?
 

bwat

EE
Location
Western PA
Occupation
EE
It's been debated here many times, but I'm in agreement with Larry.

The code states (my bold)
"Where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation,.."

To me, this means that you start with the code's minimum that you would have had to use based on that specific installation (so after temperature correction.. after # of CCCs in a raceway), and then you only have to increase EGC if you go beyond that size. In other words, if your ungrounded conductors are as small as the code would allow for that installation, then there's no need to increase your EGC.

I don't know that this is what the code writers meant when they wrote it that way, because it doesn't make perfect sense, but this is what it says. Something kind of like the "Charlie's Rule" thing that get mentioned here sometimes.
 

augie47

Moderator
Staff member
Location
Tennessee
I agree, not increased in this case.
If my memory serves me (Ha!), one earlier Code cycle stated 'for any reason" and the wording was changed to the present to address issues such as this one.
 
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