That’s clear as a bell. 
Yes that is one job of the EGC but this doesn’t always happen. Just as the freezer in the garage that keeps tripping the GFCI. This freezer has a high impedance fault, not enough to trip the breaker but enough to trip the GFCI device.
There is a fault in this freezer and it is not enough to trip the breaker but enough to trip the GFCI. The current is flowing in parallel with the neutral and equipment grounding conductor but not enough to trip the breaker.
Parallel circuits will have current flowing in each of the parallel pathways. In this freezer we have current on the neutral as well as the EGC. The amount of current on each will be dependent on the amount of resistance of each path and the amount of voltage present at each. The fault to the EGC might be in series with another load which would give it a less voltage value as the neutral. Now someone gets in parallel with the equipment grounding conductor and current flows through them.
The amount of current flowing through the human will depend on the amount of resistance between then and the neutral at the service. What we need to remember here is it doesn’t take much current to hurt the human body. As little as one tenth amps can be fatal. Between .009 amps and .015 amps our muscles contract or it is what is called the let go threshold. Someone with a bad heart could suffer badly at this level.
Ever touched some appliance and got a tingle? That was faulted current and you became a path for current to flow. It was going through you to earth to the grounding electrode back through the grounding electrode conductor to the neutral at the service. You were in parallel with the EGC supplying that appliance.
W.A.F.I.
So Mike, let me see if I get this. The ground is designed to take fault current away from you by putting you in parallel with a low impedance path. But it cannot take you fully out of the fault currents path because the human body is a conductor, albeit a high impedance one.
Since you are still carrying some current and it only takes a small amount to harm you, that is the reason you’re saying a ground doesn’t protect you from a shock. It may reduce the level of the shock but not enough to be considered a life saving component of the electrical system.
LOL…I thought I already explained GFCI’s and being grounded versus ungrounded. Alas I will let everyone search for it as typing it all over again would give me a headache…
Almost got it but I will keep going till you do.
The EGC is installed in the event there is a fault. It will carry the faulted current back to the service neutral and open the overcurrent device,
But in the event of a high impedance fault such as a freezer that is tripping a GFCI but works fine on a regular circuit there is not enough current being carried by the EGC to clear this fault.
Go out barefooted on a wet day and open this freezer and you are in severe danger.
This is true for a high impedance fault. It is very possible for a high impedance fault to let enough current be on the EGC that in case a person came to be in parallel with that fault they could very possibly be hurt or even killed.
This link is a good example of where the EGC did not clear a fault but had there have been a GFCI in place it would have had different results.
http://news.yahoo.com/video/orlandowesh-16122564/medical-examiner-rules-on-girl-s-death-after-mini-golf-game-29827697.html#crsl=%252Fvideo%252Forlandowesh-16122564%252Fmedical-examiner-rules-on-girl-s-death-after-mini-golf-game-29827697.html](http://news.yahoo.com/video/orlandowesh-16122564/medical-examiner-rules-on-girl-s-death-after-mini-golf-game-29827697.html#crsl=%252Fvideo%252Forlandowesh-16122564%252Fmedical-examiner-rules-on-girl-s-death-after-mini-golf-game-29827697.html)
The pump had an EGC connected to it so why did it not clear the faulted current? Could it have been because it was a high impedance fault?
A 15 amp breaker will allow 15 amps of current flow on the EGC indefinitely and not trip. If it tripped with 15 amps of fault current flowing on the EGC it would trip with 15 amps of current flowing between the black and white wires.
Yes I am saying that the EGC will not prevent you from being shocked but a GFCI device will keep the level of shock to less than .006 of 1 amp.
Yes I am saying that in a fault situation where a human is in parallel with an energized EGC it is very possible that they would receive injuries that could be fatal.
Actually we’re dicussing the role of just a ground at this point. We shifted a bit from GFCI’s. Sorry for the drift everyone but this is interesting stuff.
I understand the benefits of GFCI’s detecting low amps and how a breaker won’t trip until its full rating is reached. What im zeroing in on is the role or even perhaps the benefit or necessity of a ground.
Does the EGC then play any role, directly(e.g. shock) or indirectly(e.g. fire), in protecting life?
If it’s purpose is not in protecting people then is a ground playing a role in protecting equipment(e.g. Electronics, appliances)? One of those has to be true or we are wasting a whole lot of copper. 
The EGC plays two roles the first is to keep all exposed metal that encloses electrical equipment at earth’s potential or at zero potential.
250.4(A)** (2)** Grounding of Electrical Equipment. Normally non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.
The second is a low impedance path for fault current.
250.4(A)** (3)** Bonding of Electrical Equipment. Normally non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.
Why have this bonding”
250.4(A)** (5)** Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.
In the event of a direct fault the amount of current that would flow through the EGC would be dependent on nothing more than the resistance of the conductors and the current would be very high and the breaker or fuse would open.
But in the event of high impedance fault such as the freezer that trips the GFCI device but works fine on a regular circuit then the fault has enough resistance to keep the current below the threshold of the overcurrent device. Anyone coming in contact with this freezer is in danger. The amount of danger is dependent on the amount of available current there is in the path through the human.
Someone wearing rubber shoes little or no danger but a barefooted person a lot of danger.
If your question is, does the EGC remove all dangers of harm the answer is no. If your question is, does the EGC have a job the answer is yes.
If your question is, does the EGC remove all dangers of shock the answer is no. If your question is, does the installation of the EGC make a system safer than one without the answer is yes.
If your question is, does the EGC make a GFCI safer the answer is no. Now comes the question, “what if the GFCI has failed?”
I think the answer to that question can be found in the question. Why was the GFCI there in the first place? If it has failed is it safe? If the answer to the first question is for safety then a failed GFCI needs to be replaced and all the EGCs on earth won’t make it safe. If the answer to the second question is no then reread the sentence in front of this one.
The simple answer to that question is the failed GFCI is just as unsafe with or without an EGC would you not agree? Then how could an EGC make the failed GFCI somehow safe?
This whole discussion stemmed from my statement that I believe that having a ground and a GFCI is a safer setup than just installing a GFCI. Again, I am not saying the ground enhances the GFCI in some way. They have separate functions.
Now you have said the following two statements:
But if your first statement is true then a circuit/outlet/system is “safer” with an EGC than without, regardless of whether it has a GFCI or not.
Please don’t misunderstand, I am not trying to be aggressive or arrogant. I was told I was wrong and now after all this discussion it sounds like I am being told the very thing I said in the first place. If I and any other readers are going to expand our understanding this point has to be clear.
Having a ground improves safety.(some amount or maybe just a little)
Having a GFCI improves safety.(a lot)
Having both is a superior installation. A+B=C
How is that logic wrong?
Said real quick it does sound logical but having an understanding of how a GFCI works one knows that the EGC plays absolutely no role in the safety of the device therefore it is not logical. The EGC in no way makes it superior or safer. Any faulted current will never see the EGC if one was present so it is not safer.
The argument that it is safer if the GFCI fails does not hold water simply because if the GFIC has failed then the receptacle is not safe in the first place. It wouldn’t be safe even if it had an EGC.
If an EGC adds a factor of protection to a system, and a GFCI adds a factor of protection to a system, then both of them installed will add a greater factor of protection to a system. They will each enhance, in separate ways, the level of protection in that system. Correct?
I don’t know how else to describe my query.
The problem (as I see it) is that you’re “compounding” or adding up safety factors;
GFCI = safe, while GFCI + EGC = safer.
When a functional GFCI device is in place on the circuit, the EGC is essentially obsolete. Therefore, there is no “increase” in safety.
A circuit without a GFCI device is “safer” when it includes an EGC (assuming the appliance requires an EGC) only because there’s a chance that the breaker will trip prior to allowing a fatal condition.
Even with and EGC in place, a fault in a piece of equipment can produce a fatal shock, even if the fault is not great enough to trip the breaker.
No this is incorrect due to the function of the GFCI.
The way you are trying to arrive at you query is wrong.
[FONT=Calibri]The way you are trying to look at this is the same way I was looking at a dollar I lost on a bear hunting trip. Everyone keeps telling me that I am wrong about that dollar but I know I am right. [/FONT]
[FONT=Calibri]Two of my buddies and me went bear hunting and arrived at the place late in the evening. We searched for somewhere to spend the night in vain. Finally we found an old rundown place and the manager said we could spend the night for $10 apiece. [/FONT]
[FONT=Calibri]Each of us gave him $10 but he had to wake us early in the morning. The next morning he sent his little boy to wake us but having a guilty conscious he gave the boy 5 $1 bills and told the boy to split it up between the three of us. Well the boy couldn’t divide 5 by 3 equally so he gave us $1 back each and kept $2.[/FONT]
[FONT=Calibri]We paid $10 and got $1 back which means that we now paid $9 for the room. 9 times 3 equals 27 plus the 2 the boy kept equals 29. Where is my dollar???[/FONT]
[FONT=Calibri]No the GFCI device is not enhanced at all by the EGC. The EGC is not needed for any reason with a GFCI. To use the idea that a GFCI is safe and the EGC is safe so having the EGC makes the GFCI safer is like me hunting for my dollar above. [/FONT]
[FONT=Calibri]I would also add that the safest GFCI receptacle in the world is the one that is still in the box. So let’s add this to the equation. I have found a GFCI in the bathroom but my little $3 meter shows an open ground so I recommend that this GFCI be returned to the box it was shipped in as this is the way to make it safe again. This would make as much sense as saying that an EGC makes the GFCI safer. [/FONT]
So in this long drawn out discussion on GFCI testing with required tester we should all have more advanced equipment to make sure that the GFCI is safe and any old ones we find that do not fail in the open position should be called out.
Keep in mind that there are homes that still have them. Is there a list of the ones that don’t. In reality maybe they should make them without a ground so they can’t be tested OR USED WITH A GROUND that would solve all the problems. Then we can test them like smoke alarms by the internal beeping sound and say yes it has been tested and meets approval.
Wrong. The test button is sufficient to test a GFCI.
Any device used to test a GFCI or AFCI other than the test button on the device is a flawed test and has no value at all.
As I have said so many times before UL list in their user guides for these devices the following;
The ONLY test is the test button.
I know that there are several intelligent Home Inspectors, Electrical Inspectors, and Electricians out there but either of these who uses a plug-in tester to test either a GFCI or AFCI is doing a flawed test and any information passed on by using one of these is misinformation.
Mike I do both and test them twice. What I do not have yet is the advanced tester but I will get one after this long long long discussion.
This is exactly the point. Once the GFCI stops opening the circuit correctly(e.g. it is not functional, something I see 2-3 times a month on newer GFCIs), all you have is an open ground 3-prong outlet with no form of protection at all. You are essentially back to where you started. But if the ground is installed, you at least have it’s function available.(I am making no claims about the level or form of protection that EGC provides)
I am NOT saying the EGC makes the GFCI safer, as Mike keeps assuming. I AM saying** the EGC makes the circuit better** regardless of the presence of a GFCI.
It’s no different than saying an AFCI, surge protection or a lightning arrester would also improve a circuit/system by adding another type of protection. They all perform different functions and having them together is a better or superior installation then only having one.
No. That is not correct.