Hi Charlie,
In this particular case, I am putting three separate, small PV systems all on one commercial rooftop. Each system will interconnect into the main panel of the respective office it supplies with power. Each office has a panel filled with branch breakers and is protected by a 150A OCPD located at the top of the panel.
However, these 150amp panels are supplied by a switchgear that is in an adjacent building within the office park. The switchgear seems to be comprised of (3) adjacent sections. Each section has (6) 150 amp switches that feed the aforementioned electrical panels, for a total of 18 electrical panels being supplied by the switchgear. The whole switchgear has a 2000A load break switch. [the switchgear is a Square D Power Style Commercial Multi Metering, 208Y connection]
I'm trying to apply the 120% Rule for backfeeding the busbar throughout the whole system stream.
I'm guessing at the Switchgear sectional level, it would look something like this:
1200 amps (max. section rating) * 120% = 1440 amps
1400 amps - (150 amps * 6 [# of breakers on the section]) = 540 amps
Therefore I can backfeed up to 540 amps on this switchgear section
Is my thinking correct? Please let me know if I can clarify anything. Sometimes it's hard to convey what's in my head into words.
Andy