Isolated circuit

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In what context is the term being used?

Roger
 
A few that I can think of.

A circuit that has been been taken out of service and locked off is an isolated circuit.

A circuit that is intentionally run away from other circuits.

A single circuit that is derived from an SDS.
 
Around here they are called dedicated Circuits. Two wire circuit with ground sometimes IG ground, ran to a single receptacle, though usually a duplex or power strip is in installed. Which would seem to negate the term.
 
brian john said:
Around here they are called dedicated Circuits. Two wire circuit with ground sometimes IG ground, ran to a single receptacle, though usually a duplex or power strip is in installed. Which would seem to negate the term.
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They are as brian stated. Sorry getting late.
 
Shockedby277v said:
To feed isolated outlets for computers.
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This would typically mean an Isolated Ground circuit. This would be a circuit with two EGC's, one will ground/bond the conductive surfaces such as the raceway and boxes, the other will be dedicated to the receptacle.

This involves the use of an Isolated ground receptacle or non-metallic raceways and boxes and a standard receptacle.

See 250.96(B), 406.2(D), and 640.7(C) (there are other references as well) for a little information on where they would be used.

Roger
 
roger said:
This would typically mean an Isolated Ground circuit. This would be a circuit with two EGC's, one will ground/bond the conductive surfaces such as the raceway and boxes, the other will be dedicated to the receptacle.

This involves the use of an Isolated ground receptacle or non-metallic raceways and boxes and a standard receptacle.

See 250.96(B), 406.2(D), and 640.7(C) (there are other references as well) for a little information on where they would be used.

Roger
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Ok. I'm following so far. As I thought. Here is my question. Do you need a seperate grounding system for isolated ground circuits?? Also, EGC #1 is used to ground your conduit, boxes etc etc and EGC #2 is used for the isolated ground receptacle. If am running 3 isolated ground circuits in a conduit, do I need to pull 4 grounds or 2 for them?? Do they all terminate to the same ground bus?
 
Isolated ground systems are common at the same connection as the neutral ground bond, from that point their are isolated, in the instance you mentioned you would need an IG for each brach circuit, a neutral for each branch circuit and you could use one EGC.
 
I agree with Brian 100%.

I will add that in todays world most Isolated ground circuits are not needed or functional in what they are expected to do even though they may be shown on the prints.

Roger
 
To make sure I get this straight, the IG will terminate at the service ground bus?? to make it officially isolated?? Sorry for so many questions, my prints are poor.
 
Shockedby277v said:
To make sure I get this straight, the IG will terminate at the service ground bus?? to make it officially isolated?? Sorry for so many questions, my prints are poor.
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Or at the neutral/bond connection of a transformer that creates an SDS.
 
Shocked, here is an illustration from Ed MacLarren that may help.

IsolGnd.gif


Roger
 
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