No main breaker

[SAP]

I have what I believe is a 100 amp 2 space with no main breaker, how would I calculate my backfeed breaker if I have no main to calculate only my bussing thanks

 

[SAP]

Maybe this is a little easier wording for what my question is. if I have a 125 amp bussing with a 100 amp main I can back feed 120% off my bussing is 50 amps. Take the 100 amp main out of the equation how much can I back feed just using the bussing thank you

 

[ggunn]

I have what I believe is a 100 amp 2 space with no main breaker, how would I calculate my backfeed breaker if I have no main to calculate only my bussing thanks

If there is no main breaker then if you interconnect in the panel it is a line (supply) side connection and the bus calculations in 705.12(D)(2)(3) do not apply. Your AHJ may have specific rules to follow in this case so it behooves you to consult with them.

 

[pv_n00b]

These are great interconnections as any breaker in the panel is a supply side interconnection, assuming your AHJ and utility allows them. If you have a 125A bus and the service conductors are rated for 125A then you can back feed 100A of PV.