The situation I have is a main 200a panel in a dwelling with a 100amp sub panel that was run for a home work shop. This was done when the home was built. The location of this sub panel makes future wiring very difficult, not only it's location but it was flushed mounted. My question is can i add a 100a two pole breaker to this existing sub or should I find a 90amp breaker. The existing sub panel will still have a load on it that is related to the work shop