? on isolated ground

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Old 04-10-09, 04:00 PM
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? on isolated ground

Hello, I am not an electrician and am not doing a job. I am going to school to be a Technician and have a question about something I've read. What exactly is an isolated ground? I've heard of something like a computer or soundboard for example requiring it's own isolated ground. Does this mean that the circuit that one of these components are on would have its own bare ground wire that runs back to the main panel and connects to the grounding bus bar? Or does an isolated ground mean that this circuit would run back to the main panel and stay isolated from the rest of the panel and connect to its own grounding device (like a driven ground rod)?

Thanks Dennis
 
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Old 04-10-09, 05:55 PM
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well, the first thing you should learn is that all grounds are bonded together to a common grounding electrode system.

an isolated ground means there is an INSULATED (to avoid electrical contact with any other grounded metal) from the receptacle back to the main service. If there is a sub-panel in between, that one specific ground is not bonded to the other equipment grounding conductors (EGC's) in that panel but continues on back to the main panel.

Now, here is an odd part of isolated grounding systems;

if there are multiple circuits from a sub-panel that are iso ground, they all will be bonded to each other on an isolated ground bar in that panel. Then, from there back to the main panel, there will be the iso ground (1 wire) as well as the normal EGC (another wire). It effectively removes it from being completely isolated but apparently they have found that it is not worth dragging more than 2 egc's back to the main panel.
 
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Old 04-10-09, 07:30 PM
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Basically it is like a second neutral system, except the wires are colred with green insulation, and at the receptical connecting to the ground slot is islolated from the yoke and device box.
 
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Old 04-10-09, 10:21 PM
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Originally Posted by classicsat View Post
Basically it is like a second neutral system, except the wires are colred with green insulation, and at the receptical connecting to the ground slot is islolated from the yoke and device box.
No way!!!! a neutral is a current carrying conductor. An egc shouldn't carry current unless there is a fault.

the explanation of the connection is correct.
 
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