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Old 08-13-2012, 09:36 PM   #1
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Need Help Understanding Neutal / Ground


What's the difference between neutral and ground? Doesn't the ground get tied to the neutral in the main panel?

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Last edited by gookinp07; 08-15-2012 at 01:59 AM. Reason: Fixed Title: "Neutal" -> "Neutral"
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Old 08-13-2012, 09:46 PM   #2
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Need Help Understanding Neutal / Ground


Very basic, and worded for this site:
Neutrals carry circuit current (amperage) for 120V loads. This is why neutrals are always insulated.
Equipment grounds only carry fault current for extremely short periods of time.

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Old 08-13-2012, 09:52 PM   #3
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Need Help Understanding Neutal / Ground


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Originally Posted by gookinp07 View Post
What's the difference between neutral and ground? Doesn't the ground get tied to the neutral in the main panel?
It does, but as speedy mentioned already, one carries current on purpose, the other does not, unless a fault occurs... to get a little deeper in this, the reason we have to install a ground wire instead of just using the neutral conductor for safety, is that all the current flowing on the neutral conductor would cause objectionable current on items that we would not want, say plumbing pipes for example, this would be bad if the plumber cut this pipe and got in the middle and completed the circuit...

This is a rough explanation, but should get in some perspective.
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Old 08-13-2012, 09:52 PM   #4
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Need Help Understanding Neutal / Ground


Im not great at explaining things, and im sure the others will give much better description

Theoretically they can be the same. However there are important differences.
Ground is simply put "a ground", where the path leads to actual earth.

Neutral, however, is a "grounded conductor" with conductor being the operative word.
Take a light for example. There are two basic wires for a simple incandescent light to work.
The black(hot) sends electricity to the filament, and the white is return current completing the circuit.

A neutral can be a ground, but a ground can never be used as neutral.
Although neutral is not a main current carrying conductor, it can carry current. Grounds should not

And Petey beat me... they dont call him Speedy for nothing.

And so did stickboy!! Typing on my phone is too slow
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Old 08-13-2012, 10:05 PM   #5
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Need Help Understanding Neutal / Ground


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Originally Posted by gookinp07 View Post
What's the difference between neutral and ground? Doesn't the ground get tied to the neutral in the main panel?
That's true. In short neutral or the grounded conductor is a current carrying wire and is part of the completed circuit with the serving transformer.

Ground when speaking about the Equipment grounding conductor in your branch circuit wiring is not a current carrying wire. It only carries current when a ground fault occurs and provides a path for the fault current to get back to the transformer so that a breaker will trip and open the circuit.

Neutral current and ground fault current must be able to get to the transformer to complete a circuit be it a typical 120 volt circuit under normal operation or a fault circuit. At the main panel they are bonded to the utility neutral which is the only low impedance/resistance path back to the transformer. Fault current must use the service neutral at the main panel so you bond them there. Study this drawing below I made and I think you will see what is going on. If there is a ground fault (hot wire touches metal box for example) it will transfer to the ground (green line). There will be no load (appliance) to limit the current. So much current will flow on the ground (egc) that the breaker will trip on covercurrent. Grounded leg is your neutral.
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Last edited by Stubbie; 08-13-2012 at 10:13 PM.
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Old 08-13-2012, 10:08 PM   #6
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Need Help Understanding Neutal / Ground


This is it in a nutshell.

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Old 08-13-2012, 10:13 PM   #7
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Need Help Understanding Neutal / Ground


So much for keeping it simplistic. Nice drawing
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Old 08-13-2012, 10:17 PM   #8
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I guess the main thing I don't understand is how the neutral and ground are seperate. If a panel has 1 bar to connect all of your grounds and neutrals to, how are the two wires supposedly seperate? If your appliance has a ground fault, how does the breaker detect the fault if your neutral is connected to your ground at the main panel?

The reason I'm asking is because I ran a 240v line (2 hots and a ground) to a pier. In another thread, I explained how I found out that electricity appeared to be leaking from the 240v winch to an aluminum ladder in the water. I unhooked the winch, killed the main breaker for the house, and ran a wire from the ground in the 240v socket on the pier to the aluminum ladder in the water. There's 1.5 volts in my ground wire. How is this possible?

I believe the ground is tied to the neutral in the main panel. The ground wire for the cable I ran connects to the neutral / ground bar in the main panel. It is the far end of the ground for this circuit that sparks when rubbed against the ladder in the water. Can anyone tell me why this is happening?

Thanks,
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Old 08-13-2012, 10:18 PM   #9
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Need Help Understanding Neutal / Ground


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So much for keeping it simplistic. Nice drawing

graphics rock!
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Old 08-13-2012, 10:21 PM   #10
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Need Help Understanding Neutal / Ground


Quote:
Originally Posted by gookinp07 View Post
I guess the main thing I don't understand is how the neutral and ground are seperate. If a panel has 1 bar to connect all of your grounds and neutrals to, how are the two wires supposedly seperate? If your appliance has a ground fault, how does the breaker detect the fault if your neutral is connected to your ground at the main panel?

The reason I'm asking is because I ran a 240v line (2 hots and a ground) to a pier. In another thread, I explained how I found out that electricity appeared to be leaking from the 240v winch to an aluminum ladder in the water. I unhooked the winch, killed the main breaker for the house, and ran a wire from the ground in the 240v socket on the pier to the aluminum ladder in the water. There's 1.5 volts in my ground wire. How is this possible?

I believe the ground is tied to the neutral in the main panel. The ground wire for the cable I ran connects to the neutral / ground bar in the main panel. It is the far end of the ground for this circuit that sparks when rubbed against the ladder in the water. Can anyone tell me why this is happening?

Thanks,
Patrick
Without knowing how an electrical system works, you really shouldn't be doing your own wiring... especially when bodies of water are involved, it is WAY more dangerous than you could ever imagine... a lot of people died this summer due to faulty wiring, and unfortunately, it wasnt the person that did the wiring, but kids... it just pains me to read about these stories....

Last edited by stickboy1375; 08-13-2012 at 10:23 PM.
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Old 08-13-2012, 10:22 PM   #11
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Need Help Understanding Neutal / Ground


Quote:
There's 1.5 volts in my ground wire.
How did you meter this 1.5V...between what two points?
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Old 08-13-2012, 10:24 PM   #12
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Need Help Understanding Neutal / Ground


I measured the 1.5 volts between the ladder and the ground of the 240v socket. It stayed constant when power was on, the circuit breaker was off, and even when the main breaker was off.
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Old 08-13-2012, 10:26 PM   #13
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Need Help Understanding Neutal / Ground


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I measured the 1.5 volts between the ladder and the ground of the 240v socket. It stayed constant when power was on, the circuit breaker was off, and even when the main breaker was off.
Sounds like it could be from someone else's power supply, should be checked into at least.... depending on time of day you took that reading, it could be elevated during high demand periods...
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Old 08-13-2012, 10:27 PM   #14
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Need Help Understanding Neutal / Ground


Shutting the main off doesn't disconnect the ground...only the hots. You may have the 1.5V on the ground of the receptacle/branch circuit wiring, not on the ladder.
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Old 08-13-2012, 10:32 PM   #15
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Need Help Understanding Neutal / Ground


Quote:
Originally Posted by stickboy1375 View Post
Without knowing how an electrical system works, you really shouldn't be doing your own wiring... especially when bodies of water are involved, it is WAY more dangerous than you could ever imagine... a lot of people died this summer due to faulty wiring, and unfortunately, it wasnt the person that did the wiring, but kids... it just pains me to read about these stories....
Agreed .. 5 people died on Lake of the Ozarks in Missouri this year due to faulty electrical wiring. One case wasn't the fault of the dock owner but faulty wiring on a boat that was docked to his and using his power.

It's not uncommon to have an external source causing the problem. His problem may not be from his wiring. He says he has all power off and still has the spark when connecting a ground wire to his receptacle and touching the metal ladder. I wish he would stop experimenting.....

EDIT .. Sorry for the redundancy I see it has already been brought up

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Last edited by Stubbie; 08-13-2012 at 10:36 PM.
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