There may be a little more to this.
Example: The EZTRAK will put 12 VDC to the drives on the drive enable line to turn them OFF. I know this because I pull the green connector out of the AUXBOB to kill this 12VDC to turn the drives ON and see which one is generating the axis drive fault.
So I believe the V2XT, Boss 8 and 9, and such do have those large contactors isolating the motors from the drives and a drive enable signal going to the drive boards.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)