100A CENTER FED main panel has 100A SUB PANEL BREAKER

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Designer101

Senior Member
Location
California
Occupation
Solar and ESS Designer
under what conditions is this allowed, i checked the total load calcs, its over 100A. Homeowner has permit for both main and sub panel. looking deeper the wire feeding sub panel are both different in sizes(yes L1>L2) I need to connect just 20A pv breaker i might do that in sub , but just wanted to take your advice before proceeding is it safe to proceed. What if AHJ Notices this unusual activity later.
 

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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
What is the main panel busbar rating? If it's 125A you can connect to the sub as is. If it's 100A then you're suppose to move the subpanel breaker to one end of the panel.

Whether the AHJ will notice the existing issues is a separate concern.
 
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Designer101

Senior Member
Location
California
Occupation
Solar and ESS Designer
jaggedben said:
What is the main panel busbar rating? If it's 125A you can connect to the sub as is. If it's 100A then you're suppose to move the subpanel breaker to one end of the panel.

Whether the AHJ will notice the existing issues is a separate concern.
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PROBABLY 125A per my guess, dont have labels in it as they have so many loads both in main and sub panel.
we have to move the sub panel breaker at the end because its center fed type?
Is there any code reference to it i can look into?
thank you
 
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Designer101

Senior Member
Location
California
Occupation
Solar and ESS Designer
Sierrasparky said:
How it it different?

Also If a new electrician touches it they could be responsible to fix all.
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the story is how did this panel get inspected and approved for another sub panel installation, the wire sizes feeding sub panel are different in size, the load calcs crossed definitely 125A.
i am just doing GMA so inspector will not even bother to look at the main panel.
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Designer101 said:
PROBABLY 125A per my guess, dont have labels in it as they have so many loads both in main and sub panel.
we have to move the sub panel breaker at the end because its center fed type?
Is there any code reference to it i can look into?
thank you
Click to expand...

See 705.12(B)(3)(e) in the 2017 NEC.

Centerfed isn't really different or special anymore in dwellings. If the sum of your sources are over 100 percent of the busbar (they must still be under 120 percent) then the breaker has to be at the opposite end. In the case of center-fed panels they let you use either end but not both.
 
kwired

kwired

Electron manager
Location
NE Nebraska
grich said:
In the Homeline pic, it's a shame a GFCI receptacle wasn't used on that one slot...then they could cram another 20A tandem in there. ;)
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Really shouldn't have needed a main breaker in that "Homeline" panel, isn't the 100 amp breaker in the other panel the feeder to the "Homeline" panel.

BTW I pretty sure that is not a Homeline panel, maybe a GE or Siemens?
 
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