I currently have a Squared D 3 phase 400A NQM style main breaker inside a panel. The panel is now essentially full and I want to add a sub panel for expansion. The subpanel is 200A. My problem is how ro feed the sub panel. Are there add on kits or lugs to allow this? I even looked at a simple 3 pole 200A braeker to install in the main panel, but as with most applications, these breaker drop off at 150A. Ideas?