I am a Nevada County Building Inspector in CA. I had this come up twice today in consecutive inspections.
A detached garage is fed from the main service panel with a 2-pole, 40A breaker and two No. 8 copper plus neutral and ground. The panelboard in the garage has two 20A breakers for outlets and one 15A breaker for lights. The branch circuits are sized correctly. I am being told that the OCPD and feeder wires from the house to the garage must be sized to the rating of the panelboard in the garage, which is 125A. At 100 ft distance from house to garage this is approx a No. 1 copper conductor. This guy only installed a 3/4 in. conduit. Do I size to the load or the panelboard rating? And if its to the panelboard rating must it be equal to or greater to the panelboard rating or must it be less then?
Thanks in advance for your assistance.