Neutral and ground

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Re: Neutral and ground

I agree with Charlie. (If I had a dollar for every post I have started that way).

Its one thing to explain electrical safety to a DIY'er and another thing to tell him what size wire to use for his weekend project to upgrade his service entrance.

I think you guys did a good job of educating the original poster to dangers of a practice that is a common word of mouth solution. Hopefully lots of lurkers will read the thread.
 
Re: Neutral and ground

Hello: Ia m the original poster, and have one more question (sorry!!!).

I understand the danger when a neutral is lost and 120 volts could go over the ground wire to the earth. My question is, why doesn't electricity (some number of volts) ROUTINELY go over the ground wire, since the ground and neutrals are essentially hooked together in the CB panel on the bus bar? Is the answer simply that the electricity running on the neutral takes the "easier" path of going directly to ground rather than over the bare wire? Thanks again to all who have replied to and educated me.
 
Re: Neutral and ground

Is the answer simply that the electricity running on the neutral takes the "easier" path of going directly to ground rather than over the bare wire
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You have fallen victim to a very common myth. The current is not trying to go to ground or earth, it can only return to its source at the transformer. The only path back to the source from the load is the neutral in a correctly installed circuit. There is some neutral conductor current in the earth between the service disconnect and the utility transformer. This is because the neutral it bonded to the earth at both of those locations and current will flow on all available paths.
Don
 
Re: Neutral and ground

Originally posted by jmattero:
My question is, why doesn't electricity (some number of volts) ROUTINELY go over the ground wire, since the ground and neutrals are essentially hooked together in the CB panel on the bus bar?
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It's because the 'bare' wire is only connected to the case of the device, and the neutral is only connected to the internal electrical parts.
 
Re: Neutral and ground

"why doesn't electricity (some number of volts) ROUTINELY go over the ground wire, since the ground and neutrals are essentially hooked together in the CB panel"?
This is because there is no potential present. The electrons only flow when there is a potential, commonly called "voltage", present. It's sort of like a blind alley. Why bother.
~Peter
 
Re: Neutral and ground

Originally posted by peter:
"why doesn't electricity (some number of volts) ROUTINELY go over the ground wire, since the ground and neutrals are essentially hooked together in the CB panel"?
This is because there is no potential present. The electrons only flow when there is a potential, commonly called "voltage", present. It's sort of like a blind alley. Why bother.
~Peter
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To be more precise, current flows when (a) there is a voltage difference, or potential, between two points, and (b) a conductive pathway exists between the points.

An overcurrent exists when the conductive pathway does not have enough impedance to limit the current level to a safe, but useful, level.
 
Re: Neutral and ground

Originally posted by jmattero:
Ok, thanks to all who replied. I still have one question... is a 2 prong receptacle allowed in the code? Why would this be allowed if there is such a danger with a short in an appliance shocking the person who next touches it (since it would not trip the breaker)? It would seem to me that that danger would make a 2 prong receptacle illegal, but, since they sell them at Home Depot, I would guess that they are, in fact, allowed by code. Am I still confused???
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The constitution of these United States forbids the adoption by any legislative body of "ex post facto" laws. That means that the legislature of your state cannot make an act illegal after it has occurred. When your two wire receptacles were installed they were the state of the art at the time. It is best practice to upgrade them but it may not be required at law.
--
Tom Horne
 
Re: Neutral and ground

Just because Home Depot sells stuff does not make it legal, a good quality product or for that matter safe.
 
Re: Neutral and ground

Originally posted by Leitmotif:
Just because Home Depot sells stuff does not make it legal, a good quality product or for that matter safe.
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I'll agree with you about low quality but people are responsible for their own actions and what they buy. I would not say anything that I could buy at the electrical department at Home Depot, or any hardware store or supply house in this country is "unsafe" or illegal, with the exception of those receptacle adapter that you can screw into an Edison socket.
 
Re: Neutral and ground

Originally posted by peter d:
I would not say anything that I could buy . . . is "unsafe" or illegal, with the exception of those receptacle adapter that you can screw into an Edison socket.
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What would be the problem with these devices?
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Re: Neutral and ground

Originally posted by LarryFine:
What would be the problem with these devices?
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No grounding connection. 406.3(A)


The conductors connecting the lamp socket to the branch circuit wiring are likely to be 16 or 18 AWG. You would never think of using 16 or 18 AWG to connect a duplex to the branch circuit wiring. This could be a problem if someone plugs 15 amps of load into that screw in adapter. :p

And then there is this.

410.47 Screw-Shell Type.
Lampholders of the screw-shell type shall be installed for use as lampholders only. Where supplied by a circuit having a grounded conductor, the grounded conductor shall be connected to the screw shell.
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Re: Neutral and ground

Originally posted by LarryFine:
Originally posted by jmattero:
My question is, why doesn't electricity (some number of volts) ROUTINELY go over the ground wire, since the ground and neutrals are essentially hooked together in the CB panel on the bus bar?
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It's because the 'bare' wire is only connected to the case of the device, and the neutral is only connected to the internal electrical parts.
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To Larry's answer I will add that electric current requires a complete path from source to load and back again to source. The ground and neutrals are connected at the main panel, but not at the load. So current will go from the source, along the "hot wire," to the (let us say) power tool, passing through the case without touching the case, through the tool's electric motor, back out the case, this time along the neutral, and along the neutral back to the source. There is no connection (internal to the tool) between the ground wire and either the hot or the neutral. So there is no complete path for current to flow in the ground wire.

That, in fact, is the reason for the ground wire in the first place. If something breaks internal to the tool, and if the hot wire comes into contact with the case, there would be two new complete paths for current to flow back to the source. One new path would be through your body. Not good. The other new path is along the ground wire back to the source. That second new path has very little resistance, and the current flowing will be high. That will cause the breaker to trip. The ground wire protects you from electrocution because it provides a means to trip the breaker.
 
Re: Neutral and ground

Let me start out, I am not an electrician also. Today, an electrician installed GFI's and said that he is jumping the ground to a neutral in my house. It didn't sound right to me. Hence the internet search to find your informative information. Thank You! I don't think it was up to code (as he said it was). How much time do I have to undo his doing?? I am worried now, and out of several hundred. Am I obligated to pay for his mess? It seems like he should have to back it out without charging. Any help would be appreciated. The house is in Bellevue Washington if that matters.
 
Re: Neutral and ground

Originally posted by Ronb:
Let me start out, I am not an electrician also. Today, an electrician installed GFI's and said that he is jumping the ground to a neutral in my house. It didn't sound right to me. Hence the internet search to find your informative information. Thank You! I don't think it was up to code (as he said it was). How much time do I have to undo his doing?? I am worried now, and out of several hundred. Am I obligated to pay for his mess? It seems like he should have to back it out without charging. Any help would be appreciated. The house is in Bellevue Washington if that matters.
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Re: Neutral and ground

Originally posted by Ronb:
Let me start out, I am not an electrician also. Today, an electrician installed GFI's and said that he is jumping the ground to a neutral in my house. It didn't sound right to me. Hence the internet search to find your informative information. Thank You! I don't think it was up to code (as he said it was). How much time do I have to undo his doing?? I am worried now, and out of several hundred. Am I obligated to pay for his mess? It seems like he should have to back it out without charging. Any help would be appreciated. The house is in Bellevue Washington if that matters.
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RonB:
If you read this entire thread, you will see that it is both wrong and unsafe to "jump the neutral". THe way to see if that is what was done would be to take the cover off of the GFI receptacle, remove the GFI, and look to see if there is a short piece of wire which connects the green screw of the GFI to the silver screw on the side of the GFI. If that is the case, then the electrician "jumped the neutral". All that this does is to fool the tester (the tester will show that it is wired correctly). However, as all of the people have explained, this is an unsafe situation. You can still have a GFI where you have it, and it will function properly, by simply removing that short piece of wire, and adding the sticker that says that there is no ground. This is perfectly legal, and up to code, since it is safe. Some inspectors may dispute that is is hooked up correctly, but, in this thread there is a reference to the specific paragraph of the NEC Code which clearly states that it is within the code. Good luck.
 
Re: Neutral and ground

In the case where you are protecting a 2-wire 120v residential wiring (hot & common) in a bathroom (or it could be a kitchen) with a gfci, and I can verify that the water pipes in the area are continuous back to the property entrance and service panel ground strap, would it be better to run the gfci ground to the local water pipe, or leave it off?

Another closely related question, in the case where gfci is protecting 2 wire downline wall receptacles (with three prong plugs), is it prefered if the gfci is grounded where possible even though the downline plugs are not?

And last, if the gfci is not grounded, but down line there is a ground available (due to accessability to run wires for a ground), is it preferable to ground downline where possible, or does that cause some further complication for the gfci to function properly.

My thought would be to always connect the ground if possible in all these cases.
 
Re: Neutral and ground

Originally posted by kdb4:. . . would it be better to run the gfci ground to the local water pipe, or leave it off?
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You don't ground things by connecting to local water pipes.
300.3(B): All conductors of the same circuit . . . and all equipment grounding conductors . . . shall be contained in the same raceway. . . .
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Today, you might be able to verify the pipe is continuous all the way back to the meter. But you can't stop the plumber from doing a repair in two years, replacing copper with PVC at some point between the meter and your "ground connection."
 
Re: Neutral and ground

Although I don't advocate doing so, 300.3(B)(2) allows you to run an equipment grounding conductor independent of the circuit conductors if done in accordance with the provisions of 250.130(C). 250.130(C) allows doing this for nongrounding receptacle replacements or branch circuit extensions. BUT if you're going to run back to the water piping, it must be to that portion that is within the first 5' of it entering the building. That's the only portion considered to be part of the grounding electrode system. You could also connect it to any accessible point on the grounding electrode conductor, the equipment grounding bar in the panel, or to the grounded conductor at the service equipment.

Also, be careful when replacing nongrounding type receptacles with GFI receptacles and feeding down stream. 406.3(D)(3)(a)&(b) prohibit making an equipment grounding conductor connection from an ungrounded GFCI receptacle down stream to grounding type receptacles.
 
Re: Neutral and ground

Originally posted by mvannevel:
Also, be careful when replacing nongrounding type receptacles with GFI receptacles and feeding down stream. 406.3(D)(3)(a)&(b) prohibit making an equipment grounding conductor connection from an ungrounded GFCI receptacle down stream to grounding type receptacles.
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If you don't mind, I'd like to add that this also applies to the cables between the downstream receptacles; the EGC terminals should not be interconnected.
 
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