This Arrakis 2000SCT-12S Console has been modified in the shop to have a convenient grounding buss in front of the three circuit cards.  It a #12 bare copper wire soldered to and anchored by solder lugs, which are screwed to the metal console base.  Wiring, in this studio, is brought up through holes in the counter top to connect to the ground buss and audio inputs/outputs on the console cards 

Making the right decisions will result in clean hum-free audio.