There was a question about wiring a disconnect, and the answer indicated direction of current through the breaker. What would happen if the disconnect was wired in reverse with the load coming off the top instead of the bottom of the breaker?

I will guess that the line wire is not long enough to reach the Top Side Line of a breaker disconnect.

A breaker or disconnect switch will work just fine feeding it either way.

However, Line is traditionally at the top.

If the Line is connected to the bottom, one the breaker must be rated for back feed, and special labeling must be clearly visible indicating that the Line side is at the bottom.

This is rarely done, expect in certain situations due to arrange meant of equipment and cabling.

This will not be allowed if the reason is only due to short cable.

It's a clear violation if you ignore the equipment's labeling--where it indicates the line side. (Pretty much what TK said in his fourth line)