CNC electrical noise issues - What do you think about this video ?

This would imply to me that the encoder cable shielding for example should be grounded to a "rod in the ground" earth, while the rest of the machine is grounded to the power company ground. And yet CNC machines never are actually grounded that way are they ?

http://www.youtube.com/watch?v=DOoyrsi6ctk

Btw, is he really reading over 3 volts noise ?? That's amazing if so...