Existing or not

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wlcrotts

Member
I recently did service up grade on old house that had outside pannel with 1 100amp breaker to protect sub pannel inside house. We changed outside pannel to 200amp and added 2 branch circuts one for water heater and one for dryer. Inside pannel is full and pretty well loaded.Do I need to use 80amp breaker on #2serAL to sub pannel or could it stay at 100amp as existing.
 

Strife

Senior Member
Common sense would say yes to the 100A
I mean, it's been 100A for how long? You haven't added any load right?
But then again, common sense is dead nowadays.
Sorry for that bitter taste foul smell.
So yes, you have to change to 80A

I recently did service up grade on old house that had outside pannel with 1 100amp breaker to protect sub pannel inside house. We changed outside pannel to 200amp and added 2 branch circuts one for water heater and one for dryer. Inside pannel is full and pretty well loaded.Do I need to use 80amp breaker on #2serAL to sub pannel or could it stay at 100amp as existing.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Because you changed the service and added breakers in the service panel you have now changed the feeder to the panel from a main power feeder to a standard feeder and therefore you can't use Table 310.15(B)(6) so you would have to change the breaker protecting the panel to an 80 amp breaker (Under the 2008 NEC)

Chris
 

dana1028

Senior Member
You didn't mention what code cycle you are on.

As Raider indicated, if you are on the 2008 NEC then you are stuck with an 80A breaker, but if you are on the 2005 or 2011 you can use a 90A breaker.
 

trojans4

Member
Location
Iowa
So why using the 2011 code could you not use a 100A breaker? Table 310.16(B)(7) for service and feeders says 100A for 2AWG AL. So, what code(s) sections would get you to 90A breaker? I am not arguing just asking.
 

kwired

Electron manager
Location
NE Nebraska
So why using the 2011 code could you not use a 100A breaker? Table 310.16(B)(7) for service and feeders says 100A for 2AWG AL. So, what code(s) sections would get you to 90A breaker? I am not arguing just asking.

310.16(B)(7) only applies if the service or feeder conductor is supplying the entire dwelling load.

SE cable was limited in 2008 NEC to 60 degree ampacity column of 310.16.
 
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