200 amp panel for new basement: ground and neutrals on same bus
I hired an electrician to wire my new basement (previously unfinished). He installed a 200 amp cutler hammer box right next to the main house box (which is also a 200 amp cutler hammer). He fed the basement box using two 100 amp breakers that he located in the main box. The main box is full and the basement box is about half full.
The main panel has the grounds and neutrals intermixed on both bus bars and it is my understanding code allows this. The basement panel also has grounds and neutrals mixed on both busses. My understanding is that on subpanels grounds and neutrals must be separated.
Is my basement panel considered a subpanel? When I turn off the two 100 amp breakers in the main panel feeding the basement panel the basement panel has absolutely no power in it.
If it is a subpanel do I need to have it rewired? Thanks.