Don
I realize the code does not technically prohibit this installation but many inspectors will give you a hard time when they see splices or wires passing through the panel. Commercial panel boards typically have very large gutters so a few extra wires would not be a problem but some of the load centers used for residential projects are pretty small. I don't think it would be worth an argument with an inspector or trying to figure out the gutter area of the panel. Since we don't know the size of his panels or the number of conductors passing through I felt it was better to recommend using j-boxes for this installation but he would most likely be code compliant without them.
Curt
