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05-24-2011, 10:36 PM   #1
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## Grounding question ???

I hope this question makes sense. I have learned much about electricity lately, alot from forums like this. I understand that the neutral bar is bonded to the ground bar in a main panel. I have also read that the power company neutral is grounded at the pole peiodically. Given this, my question is where does the current that returns to the panel via the neutral wires "go"? Does it return to the power company or just go to ground? Which has lower resistance, the earth or the path to the power company?

Thanks.

05-24-2011, 10:44 PM   #2
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Back to the source transformer. It's a closed loop system of sorts.

The neutral's connection to ground has no effect on function. That connection serves other purposes.

Last edited by jlmran; 05-24-2011 at 10:50 PM.

05-25-2011, 02:55 AM   #3
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Quote:
 Originally Posted by Bicoronal where does the current that returns to the panel via the neutral wires "go"? Does it return to the power company or just go to ground? Which has lower resistance, the earth or the path to the power company?
It goes back to the transformer via the service neutral wire. It's a closed loop: from the transformer to the house on either hot wire, through the loads in the house, and back to the transformer on the neutral wire. That explanation is highly simplified to the point of almost being wrong, but it's an easy way to understand the general concept.

During normal operation, there is no current flow to ground. The only time current flows through the ground is when there is a serious problem. The path back to the transformer always has much lower resistance (a fraction of an ohm) than the grounding electrode (tens or hundreds of ohms). The ground connection is not useful as a current return path.

05-25-2011, 06:57 PM   #4
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Quote:
 Originally Posted by mpoulton That explanation is highly simplified to the point of almost being wrong, but it's an easy way to understand the general concept.

What about it is approaching the realm of wrong?

05-25-2011, 07:20 PM   #5
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Quote:
 Originally Posted by jlmran What about it is approaching the realm of wrong?
Current actually goes both ways on each wire; since it's AC there's no real direction of flow. Also the current through each hot wire offsets the current on the other hot wire so only the difference between them flows in the neutral. It's otherwise accurate, and a very convenient simplification to help people understand the general idea.

05-25-2011, 09:46 PM   #6
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Quote:
 Originally Posted by mpoulton Current actually goes both ways on each wire; since it's AC there's no real direction of flow. Also the current through each hot wire offsets the current on the other hot wire so only the difference between them flows in the neutral. It's otherwise accurate, and a very convenient simplification to help people understand the general idea.
With AC there IS a direction of flow...but the direction changes (alternates) rapidly. The flow still exists. The 'offsetting' flow you mention only exists in 240v or MWBC circuits. And in these scenarios the flow remains to and from the transformer. I think the original answer is spot on.

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