Table 310.15(B)(7)

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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Yes, but the requirements have been re-written into the language of the section, so they have not significantly changed. Your service conductors or 'whole-dwelling feeder' conductors can be sized for 83 percent of the rating of the service or feeder.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
My support for the removal of this section very nearly got me thrown out of a van in motion in Florida once. Long story... :)


I tend to feel the same way. Not throwing you out of the van but removing it. Although I have never seen issue with it, I have seen violations of the rule almost everywhere. Bid a job to be compliant and someone else does it cheaper and without being compliant.

I am comfortable, However with the 83% rule but it will be applied in areas not meant for it to be used.
 

mike1061

Senior Member
Location
Chicago
What was wrong with it? It seemed clear to me.
And are you saying that for residential services and feeders you use 310.15 table and multiply by 83%?
Do you use the 90 degree column or 75 degree?
Thanks
Mike
 

kwired

Electron manager
Location
NE Nebraska
What was wrong with it? It seemed clear to me.
And are you saying that for residential services and feeders you use 310.15 table and multiply by 83%?
Do you use the 90 degree column or 75 degree?
Thanks
Mike
83% typically gives you same conductor size as was in the older tables.

What is different and more clarified is ampacity adjustments.

Before most were just using size mentioned in the table and it wasn't all that clear if needed or how to apply adjustments, now if you have more then three current carrying conductors or a high ambient temp you still do usual ampacity adjustments, but can have a conductor that is 83% the Table 310.15(B)(16) values - after adjustments are made.
 
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