WARNING - I don't have my Code with me, so I can't look this up myself. Apologies in advance for possible idiot factor.
The garage isn't operating under independent service... it's being fed from an OCP inside the house.
With one throw of the hand, you can D/C everything by turning the 60A in the house off, correct? (and secure by LOTO since no line-of-sight if needed)
So why would this still fall under the "6-throw" limit, if _not_ fed by a service separate fro the house?
