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Line side/Load side versus Bus side/Line side

Question asked by george.cole on May 1, 2019
Latest reply on Mar 22, 2020 by mamreule

Does anyone know the history and where (if one exists) for the official definition of "Line Side" and "Load Side"?


Countless standards such as the NFPA 70 (NEC), 70E, IEEE 1584, C37.20.2, and even electric equipment uses the terms throughout the text and most everyone who's worked in the electrical trade for length of time understands what they mean.  But for the life of me, I can't find where it originated from or if there's an official definition somewhere.


Now the reason for the question, we have GE switchgear, Magne-Blast breakers and ground trucks (4.16 and 13.5 kV) that uses the term "Bus Side" and "Line Side".  And as you would guess, the "BUS Side" is the supply side where as the "Line Side" is the output side to the load.  Yes, the word "Line" when used with GE medium voltage switchgear is 180 degrees opposite of what we've been taught throughout our careers.


And this has caused some confusion at my station.


Any ideas out there?