I was turned down on an inspection on a 400a overhead service. I ran 500mcm copper @ 75deg its good for 380a and I thought I could apply the next size up rule to the line side of the meter socket. As well as the fact that the load is no where near 400a I figured the wire could be derated a little. Is my thinking incorrect? The panel is is mounted on a ag building. Thank you for reading, any feedback would be appreciated.