[RE-wrenches] center fed main panel and 120% rule

August Goers august at luminalt.com
Mon Oct 15 09:32:04 PDT 2012


Hi Wrenches,



Here is yet another 120% rule question as it relates to center fed main
panels. 2011 NEC 705.12 deals with inverter point of connection and
705.12(D)(7) reads:



"*Inverter Output Connection.* Unless the panelboard is rated not less than
the sum of the ampere ratings of all overcurrent devices supplying it, a
connection in a panelboard shall be positioned at the opposite (load) end
from the input feeder location or main circuit location."



We are seeing more and more center fed main panels where the main breaker
is in the middle of the busbars and there are branch circuit breakers
located both above and below the main breaker. The question is whether it
is possible to meet the intent of the code if the main breaker is rated the
same as the panel. Here is a picture to illustrate:



https://docs.google.com/open?id=0BxRKBvO2EOGudU5KSUJnYnFRYnc



In this example, is it okay to install our inverter breaker on either the
bottom or the top? If not, then our only resort is to either upgrade the
service or downsize the main breaker which isn't always possible to do.



Thanks for your thoughts in advance.



Best,



August





August Goers



Luminalt Energy Corporation

m: 415.559.1525

o: 415.641.4000

august at luminalt.com
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