Isolated Ground Receptacles

[ArcNSpark]

Hi all, and thanks in advance to anyone who can clearly explain this to me.

Everyone knows that we use isolated ground receptacles for computers and other sensitive equipment. For the life of me, I can't find a solid explanation as to how they work.

I mean, I know that you affix the green wire to the box and the green/yellow wire to the receptacle, and I know that the receptacle is isolated from the box, but then both the green and green/yellow wires go back to the panel where they GO DIRECTLY NEXT TO EACH OTHER ON THE GROUND BAR!

One guy explained to me that the idea was to reduce the harmonics in the service, but if that's the case, wouldn't any harmonics caused by that receptacle's load be transferred to the rest of the grounding system through the grounding bar???

 

[charlie b]

Current will always seek the source that called it into being in the first place. If there is a fault internal to the outlet box, fault current would be carried along the green wire, back to the source. If there is a fault within the equipment served by the receptacle, fault current would be carried along the green/yellow wire, back to the source.

The green and the green/yellow are not connected to each other anywhere downstream of the source panel. If there is any current that happens to be flowing in the green wire, then once it hits the ground bar in the source panel, it is not going to travel backwards on the green/yellow wire towards the outlet location. The driving force is always in the direction towards the source.