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Old 08-26-2012, 02:22 AM   #31
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2 Similar GFCI, but one tests open ground


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Originally Posted by crescere View Post
Gac I posted my last before I saw your post. Thank you for that explanation. However, wouldn’t that happen even if I did not do the jumper? I have had white wires come off of outlets and the attached appliance did not become hot. The outlet simply did not work anymore.
Has it crossed your mind that there would be no reason to have the bare ground in modern wiring if all we had to do is connect neutral and ground ?

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The outlet simply did not work anymore.
And if you have a connection to ground via the neutral and you come along and touch the metal case of an appliance and turn it on ? If your body all of a sudden becomes the path needed to complete the circuit? Lets see if this will ring a bell in your thought process ...
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Old 08-26-2012, 10:25 AM   #32
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2 Similar GFCI, but one tests open ground


So everything will be fine so long as the white wire continues on its path to the main service panel. The current comes in from the black wire and out through the white wire. However, if that white wire is severed somehow along its path to the service panel the current will divert to the wire I have attached to the green ground screw, through the GFCI outlet, and to the appliance, and to any person touching the appliance. Is that right?

I have read that current going through the white wire is at 0 voltage. Is that wrong? Thank you for your patience.
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Old 08-26-2012, 10:30 AM   #33
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2 Similar GFCI, but one tests open ground


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Maybe I am not explaining what I did correctly. The GFCI was testing as ungrounded. I attached a white wire from the silver side, ie Line neutral (NOT hot), to the green ground screw.

How can I make the box hot if the black wire attached to the brass line hot side is not involved? I have touched the box and I assure you it is not hot. I understand the current returns through the white neutral wire, but I have read that it is at 0 voltage. What am I not getting?
Your not understanding your making a connection to a current carrying wire, and you are using the neutral (grounded leg of the circuit) to fool the tester. If you get in series with the neutral it can and has caused electrocutions. Lets see if you can understand this .... I leave all loads on for a branch circuit I go down to my loadcenter and turn the branch circuit breaker off. I then turn the main breaker off. Then I disconnect the neutral for the branch circuit at the neutral bus bar. I turn everything back on. All the equipment, lights and other items on the branch circuit will not work because the neutral is disconnected. I hold the bare end of the neutral wire between my fingers in one hand and touch the neutral bus with the other hand and complete the circuit.

What do you think will happen ?
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Old 08-26-2012, 10:33 AM   #34
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2 Similar GFCI, but one tests open ground


He is confusing voltage and current.
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Old 08-26-2012, 10:41 AM   #35
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2 Similar GFCI, but one tests open ground


Yes and no. You can have a voltage on the neutral in a shared neutral system. You have to remember that voltage is a measurement of potential difference with respect to another point. If a circuit is on then you will see a potential between the neutral and the ground. Consider a circuit diagram, also consider the human body as a resistor. Wherever two points of your body are touching place that into the circuit. In some cases you've now completed the path for current to get back to its source, and possibly stopped your heart in the process.

In your situation if you happen to touch a case of an appliance your possibly creating a parallel path back to the source.
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Old 08-26-2012, 02:29 PM   #36
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2 Similar GFCI, but one tests open ground


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What makes you think this?
Stick and OP (original poster)

Brain fart (senior moment, etc). I was thinking a ground neutral cross on the load side if the GFCI. The OP is bootlegging the ground/neutral on the line side of the GFCI. Agreed this will not trip the GFCI but it is still a dangerous practice.

OP, you still do not have a ground on the downstream protected receptacles and if you bootleg them, you will trip the GFCI.
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Old 08-26-2012, 02:37 PM   #37
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2 Similar GFCI, but one tests open ground


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Originally Posted by crescere View Post
So everything will be fine so long as the white wire continues on its path to the main service panel. The current comes in from the black wire and out through the white wire. However, if that white wire is severed somehow along its path to the service panel the current will divert to the wire I have attached to the green ground screw, through the GFCI outlet, and to the appliance, and to any person touching the appliance. Is that right?

I have read that current going through the white wire is at 0 voltage. Is that wrong? Thank you for your patience.
That's pretty close to correct and you are starting to understand ... congrats some never get it figured out ...

Yes the neutral or grounded leg of the circuit is at zero volts. But there is voltage and then there is current. You must create the physics that allows current to flow in order for you to place yourself in danger. The neutral is at zero volts mainly because it is coming off the neutral point (center of the winding) of the utility transformer, the ungrounded (hot) wire is coming off the end point of the transformer winding. The difference in voltage potential between the neutral and hot wire is 120 volts. Because a voltage potential exists if we connect the two ... current will flow in the circuit. In alternating current the current changes direction flowing from endpoint to center tap of transformer then reversing center tap to endpoint over the branch circuit.

If we connect a resistance (load) inbetween ... then the amperage is controlled to that of the appliance or resistance of the load. So when we turn on the light or appliance we are making that connection between the different voltage potentials and current will flow thru the load.

If we open the neutral install a jumper between the neutral of a receptacle and the green ground screw and then to the metal box we have given neutral current another path to to seek out the transformer.

If you remember anything remember this ... current seeks its source (the transformer) and it will take any path given to it to get there. IT WANTS A COMPLETE CIRCUIT.

Ground is another alternate path so if the neutral opens and you place yourself in series with something that will allow the circuit to complete and thereby make that connection between the voltage potential difference between hot and neutral, .. current will flow in the circuit.
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Old 08-26-2012, 03:33 PM   #38
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2 Similar GFCI, but one tests open ground


Quote:
Originally Posted by rjniles View Post
Stick and OP (original poster)

Brain fart (senior moment, etc). I was thinking a ground neutral cross on the load side if the GFCI. The OP is bootlegging the ground/neutral on the line side of the GFCI. Agreed this will not trip the GFCI but it is still a dangerous practice.

OP, you still do not have a ground on the downstream protected receptacles and if you bootleg them, you will trip the GFCI.
No problem... I just wanted you to rethink what you were saying.
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Old 08-27-2012, 07:04 PM   #39
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2 Similar GFCI, but one tests open ground


Ok, thanks for the explanations. Is there a text book or other reference that explains this kind of thing? Black and Decker, Home Depot books etc just give instructions on specific wiring jobs. If I want to know more about things discussed in this thread and more about grounding issues where would I look?

Also please recommend a good electricians dictionary. I looked this up in Amazon and the only applicable thing I could find pertained to UK rules. I think a good dictionary that explains the terms you guys use would help a lot. Thank you.
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Old 08-27-2012, 11:24 PM   #40
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2 Similar GFCI, but one tests open ground


Mike Holt, Tom Henry schools and your local trades bookstore should have what you are wanting. Soares is very good on grounding theory.
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Old 08-28-2012, 09:19 PM   #41
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2 Similar GFCI, but one tests open ground


Thank you I just ordered Tom Holt's electricians dictionary. His information is very reasonably priced.

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