I'm running a 70 amp sub panel to a shop addition. My primary panel will include a 70 amp breaker to supply the sub, so I really only need a main lug panel. However, Lowe's had a 200 amp. GE panel, with mains and many additional 20 amp breakers marked down from $150.00 to $60.00. An overkill but a great deal, none the less.

My question is, since I am using a 70 amp breaker at the primary, can I leave the 200 amp main breakers in the sub panel. It's really like a main lug panel, but with additional, oversized mains. I can't see that this could possibly be dangerous.

It is not the worst thing you could do. As you noted, the 200 amp breaker is limited by the 70 amp.

A pro probably would not do it, we would take the time to find the right Main Lug Only panel, of course we have direct access to more available materials, but in a pinch I see no issue with it.

Look into taking the breaker out and adding mechanical lugs to the bus bar.

Adding mechanical lugs is a great idea, but I'm not sure where to start to look for those.

A typical lug looks like the picture, found at :

http://portal.fciconnect.com/portal/page/portal/FcicntPublic/Product_Type?appname=catLanding