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Old 12-19-2009, 03:24 PM   #1
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Default Separate grounds and neutrals

Anybody know the basis for separating grounds and neutrals in sub-panels? What is the technical basis for that practice?

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Old 12-19-2009, 03:26 PM   #2
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Anybody know the basis for separating grounds and neutrals in sub-panels? What is the technical basis for that practice?
OK, I will play.

To keep normal circuit current from flowing through other paths created by grounding and bonding.

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Old 12-19-2009, 03:26 PM   #3
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So that metal parts don't carry current. Objectionable current. Is this what you mean?
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Old 12-19-2009, 03:27 PM   #4
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OK, I will play.

To keep normal circuit current from flowing through other paths created by grounding and bonding.
That's a pretty straightforward answer. Bob did write the code book
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Old 12-19-2009, 03:34 PM   #5
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Thanks. Of course, a normally connected main where ground wires and neutrals join would not have EMF available to cause current flow in the ground wires.
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Old 12-19-2009, 04:44 PM   #6
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Thanks. Of course, a normally connected main where ground wires and neutrals join would not have EMF available to cause current flow in the ground wires.

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Old 12-19-2009, 05:39 PM   #7
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Meaning what?
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Old 12-19-2009, 05:52 PM   #8
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Meaning what?

I think he means WTF are you talking about?
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Old 12-19-2009, 06:03 PM   #9
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I think he means WTF are you talking about?
Oh, okay.

Since the two conductors (EGC and neutral) are electrically identical at the main panel, then the difference between them at the sub would be only due to the voltage drop of the sub-feed neutral between the main panel and the sub-panel.

Which could be impressed on the EGC if it were connected to the neutral at the sub-panel.

Of course, the service drop neutral also drops voltage which would be felt at the buss bars in the main which have EGCs tied to them.

Interesting.
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Old 12-19-2009, 06:08 PM   #10
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If you bond your subpanels the objectional current will do a loopty loop from main to sub and not make it back to the GEC.
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Old 12-19-2009, 08:19 PM   #11
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If you bond your subpanels the objectional current will do a loopty loop from main to sub and not make it back to the GEC.
it doesnt need to go to the GEC. it goes to the. all power goes back to where it came from. XO of the transformer. the grounding system is for lightning.

we dont bond neutrals and grounds together because we need a low impedance path back to the panel. if we have a neutral with a load that has a much higher impedance than an EGC with no load. the EGC in feeders is to provide that path back to the main panel instead of using the neutral conductor.
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Old 12-19-2009, 08:22 PM   #12
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I meant transformer, I was thinking ground on pole wrote the wrong thing. Sorry for the confusion and thanks for the reason on low impedance. I can think of no argument for bonding downstream other than to give Brian John work.
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Old 12-19-2009, 10:54 PM   #13
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Egc? Gec?
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Old 12-19-2009, 10:56 PM   #14
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Egc? Gec?
Equipment Grounding Conductor.

Grounding Electrode Conductor.
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Old 12-20-2009, 12:51 AM   #15
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Default Seperate ground and neutral

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I meant transformer, I was thinking ground on pole wrote the wrong thing. Sorry for the confusion and thanks for the reason on low impedance. I can think of no argument for bonding downstream other than to give Brian John work.
Grounding has to be done only at the service because it is installed only for the purpose of protection from possible lightning strike, or other abberent voltages that may occur, such as a line of a higher voltage falling down on the lower voltage line...or a primary to secondary short at the service transformer. After that, bonding to ground potential must be accomplished throughout the entire system on all metal components of the system.
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Old 12-20-2009, 06:13 AM   #16
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Grounding has to be done only at the service because it is installed only for the purpose of protection from possible lightning strike, or other abberent voltages that may occur, such as a line of a higher voltage falling down on the lower voltage line...or a primary to secondary short at the service transformer. After that, bonding to ground potential must be accomplished throughout the entire system on all metal components of the system.

You seem to have forgotten we also have to do that at every SDS and in the work I do that may be many times in each building.
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Old 12-20-2009, 07:15 AM   #17
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I agree, the sub-panels are locally grounded, at least they are in residential.
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Old 12-20-2009, 07:24 AM   #18
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I agree,
With who?


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the sub-panels are locally grounded, at least they are in residential.
I do not understand what you mean, I am not saying it's wrong I just do not know what 'locally grounded' means to you.
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Old 12-20-2009, 07:35 AM   #19
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"Locally grounded" as opposed to grounding through the sub-feed conductors. In this case, each sub-panel is tied to a ground rod or other approved grounding electrode.

But, go ahead and start pissing....
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Old 12-20-2009, 07:40 AM   #20
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"Locally grounded" as opposed to grounding through the sub-feed conductors. In this case, each sub-panel is tied to a ground rod or other approved grounding electrode.

But, go ahead and start pissing....
a sub panel at a seperate building has a grounding system but a sub panel inside of a house does not have its own grounding system.

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