GFI receptacles
- Thread starter kevin Bortin
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- Illinois
- Occupation
- retired electrician
quogueelectric,
Don
My point is that it is not required to trip in a 1/2 cycle...the permitted trip time at 5mA is 7.2 seconds.
It is not needed to make the GFCI work, but it is required by the code for some equipment. See 250.114.
As far as what happened to you, we have no idea of the exact conditions, but a working GFCI will trip when the currents are not matched between the hot and the neutral, with or without an EGC. If the source of the shocking current was the hot that was supplied through the GFCI, then the device will trip.
Don
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
If this is a double-insulated tool, there is no EGC in the power cord, so that would have made no difference. You got a shock because of the water providing a pathway from the tool's internal energized parts, most likely the switch. (I know you know this already)quogueelectric said:
However, if the tool has a 3-wire cord, it's not double-insulated, and the exposed conductive parts (if any) could be what shocked you, and the EGC would bypass your body and minimize the shock hazard. (I know you know this, too)
While connecting the EGC may have stopped you from getting shocked, if it helped the GFCI trip, it's because it was more conductive than your body. If the GFCI still didn't trip, but stopped you from getting a shock, then it performed as it should have.
In any case, the fact that you're still here to argue is a great thing. Why the GFCI didn't trip is a mystery, unless it can be explored further. Either it was defective, or your shock current simply wasn't high enough to trip it.
quogueelectric
Senior Member
- Location
- new york
I understand
I understand
I understand
That your link to the gfi explanation before was probably the best single laid out presentation of how a gfi works. However it still does not explain the shock. You have heard of a New York minute? It is such a simple thing to connect a ground to a GFCI at the panel I would rather have a nuisance trip Than a nuisance electrocutionroger said:
- Location
- Massachusetts
quogueelectric said:
A GFCI does not predict a ground fault, it responds to a ground fault that is happening.
The electronics can not begin to respond until there is a ground fault. The time between sensing the fault and actually opening the circuit you will be getting a shock.
wow! just realized how far this thread had gone..
the description of the fork and knife tester was a joke, BTW.(duh)
sorry quogueelectric, if you got shocked but i'm pretty sure most of the folks on this board have, too.
my experience with a gfi was much the same as yours, yet the one i got hit by HAD a ground wire. by your logic, that should never have happened! the shock i recieved was much longer than 1/2 cycle... the test button and my tester both tripped the gfi (after the lovely hit) and this wasn't years ago, it was just a couple weeks ago.
5-7 mA , in case you don't know, is "very uncomfortable" and it would take almost 10 seconds to trip a gfi -by then, i would hope, you(or I) would let go!
and, without a ground wire, they will trip... think about it- if you are getting shocked, there is a ground, yes?
it's you....
the description of the fork and knife tester was a joke, BTW.(duh)
sorry quogueelectric, if you got shocked but i'm pretty sure most of the folks on this board have, too.
my experience with a gfi was much the same as yours, yet the one i got hit by HAD a ground wire. by your logic, that should never have happened! the shock i recieved was much longer than 1/2 cycle... the test button and my tester both tripped the gfi (after the lovely hit) and this wasn't years ago, it was just a couple weeks ago.
5-7 mA , in case you don't know, is "very uncomfortable" and it would take almost 10 seconds to trip a gfi -by then, i would hope, you(or I) would let go!
and, without a ground wire, they will trip... think about it- if you are getting shocked, there is a ground, yes?
it's you....
quogueelectric
Senior Member
- Location
- new york
You are all still missing the point
You are all still missing the point
You are all still missing the point
my real life experience is why did the rules change when I hooked up the ground. I have been very precise in explaining the surrounding circumstances. Are you an amprobe? Because I would like to know how you know how much current was flowing through you. Maybe you went to neutral and the gfci saw you as a toaster oven.mayjong said:wow! just realized how far this thread had gone..
the description of the fork and knife tester was a joke, BTW.(duh)
sorry quogueelectric, if you got shocked but i'm pretty sure most of the folks on this board have, too.
my experience with a gfi was much the same as yours, yet the one i got hit by HAD a ground wire. by your logic, that should never have happened! the shock i recieved was much longer than 1/2 cycle... the test button and my tester both tripped the gfi (after the lovely hit) and this wasn't years ago, it was just a couple weeks ago.
5-7 mA , in case you don't know, is "very uncomfortable" and it would take almost 10 seconds to trip a gfi -by then, i would hope, you(or I) would let go!
and, without a ground wire, they will trip... think about it- if you are getting shocked, there is a ground, yes?
it's you....
JohnJ0906
Senior Member
- Location
- Baltimore, MD
Just want to point out that GFCI breakers work just fine.... and I have yet to see one with a place to terminate a EGC.
EGC is NOT necessary for a GFCI to function properly.
EGC is NOT necessary for a GFCI to function properly.
cateqx
Member
- Location
- san diego ca
elec
elec
what you are saying is true for testing purposes,
but the question is ; gfci will work propperly whitout thue equipment grounding conductor?
in my experiece i say yes. remember gfci receptacles are for protecting people from getting shock,
belive me it will do its job with or withot egc.
elec
what you are saying is true for testing purposes,
but the question is ; gfci will work propperly whitout thue equipment grounding conductor?
in my experiece i say yes. remember gfci receptacles are for protecting people from getting shock,
belive me it will do its job with or withot egc.
To reiterate what almost everyone else has said, GFCI devices do NOT need an equipment grounding conductor to operate. See 406.3(D)(3) for using GFCI for receptacles on a circuit with NO EQUIPMENT GROUND. The other thing to keep in mind is that GFCI does not prevent shock. You will experience a shock prior to a GFCI opening. One additional thing to remember is that GFCI provides no protection if you are between line and neutral (grounded conductor). In that case the GFCI sees you as just part of the load. I don't quite understand your test and why you got shocked, but perhaps it was a line to neutral shock and not a line to ground shock. Once you connected the equipment ground, some of the neutral current may have returned on the equipment ground, allowing the GFCI to operate properly. GFCI is NOT and never will be a substitute for proper grounding and bonding. It is, at best, some additional protection.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
You have asserted that a GFCI device must have an EGC connected, in order to provide the protection it was designed to provide. You have offered as a ?test? a real life situation. But please understand that for the results of any ?test? to be accepted as proof of some proposed assertion, the experiment must be repeatable. It is fundamental to the discipline of science that anyone must be able to take the report of an experiment, set up the same conditions, perform the same actions, and get the same results.
I don?t suggest that anyone would like to get shocked, just to be able to duplicate your test conditions. But if we can?t see how you connected the wires, if we can?t set up an identical connection, if we can?t look at the wiring to your GFCI device, if we can?t set up a GFCI device with identical wiring, if we can?t check to see if your GFCI device was not broken and that it was not mis-wired, if we can?t use the same power tool, if we can?t stand in the same rain in the same wet clothes and have the same amount of water get into the tool in our hands, then it is not possible for us to verify your ?test results.?
All that said, clearly you experienced a very real shock. I cannot say for certain why the GFCI did not prevent you from feeling the shock. It might have been a broken device, and it might have been mis-wired. You merely connected to it; you did not install it yourself. So you might not be able to tell us whether the GFCI device itself was the problem. Indeed, as this was early in your career, it is possible that you did not connect the alligator clips in a way as to let the GFCI device do its job properly. I don?t think it will ever be possible to give you an answer to the question, ?Why did I get shocked, and why didn?t the GFCI prevent the shock.?
But I can answer the question of why it was different when you connected an EGC. It is simply that the EGC did its job, whether or not the GFCI was capable of doing its job.
I can also relate a personal experience. I had an electrician do a big job in my house about 18 months ago. It included putting GFCI protection in the kitchen countertop outlets. About 3 months ago, I touched something on the countertop while it was turned on and while my hands were wet. I received a shock, but was able to quickly let go. I probably felt the shock for under a quarter second. But I questioned whether the electrician did the install correctly. I bought a GFCI tester, and it showed the circuit working correctly. Just now I calculated, using Don?s formula, that the current amounting to the threshold of pain (about 25 milliamps) could continue as long as three quarters of a second, before the GFCI would have to trip. So now I am no longer surprised that I felt the shock, and I feel more confident that the GFCI would have prevented a more serious shock or injury, in the event that I had not been able to let go quickly.
I don?t suggest that anyone would like to get shocked, just to be able to duplicate your test conditions. But if we can?t see how you connected the wires, if we can?t set up an identical connection, if we can?t look at the wiring to your GFCI device, if we can?t set up a GFCI device with identical wiring, if we can?t check to see if your GFCI device was not broken and that it was not mis-wired, if we can?t use the same power tool, if we can?t stand in the same rain in the same wet clothes and have the same amount of water get into the tool in our hands, then it is not possible for us to verify your ?test results.?
All that said, clearly you experienced a very real shock. I cannot say for certain why the GFCI did not prevent you from feeling the shock. It might have been a broken device, and it might have been mis-wired. You merely connected to it; you did not install it yourself. So you might not be able to tell us whether the GFCI device itself was the problem. Indeed, as this was early in your career, it is possible that you did not connect the alligator clips in a way as to let the GFCI device do its job properly. I don?t think it will ever be possible to give you an answer to the question, ?Why did I get shocked, and why didn?t the GFCI prevent the shock.?
But I can answer the question of why it was different when you connected an EGC. It is simply that the EGC did its job, whether or not the GFCI was capable of doing its job.
I can also relate a personal experience. I had an electrician do a big job in my house about 18 months ago. It included putting GFCI protection in the kitchen countertop outlets. About 3 months ago, I touched something on the countertop while it was turned on and while my hands were wet. I received a shock, but was able to quickly let go. I probably felt the shock for under a quarter second. But I questioned whether the electrician did the install correctly. I bought a GFCI tester, and it showed the circuit working correctly. Just now I calculated, using Don?s formula, that the current amounting to the threshold of pain (about 25 milliamps) could continue as long as three quarters of a second, before the GFCI would have to trip. So now I am no longer surprised that I felt the shock, and I feel more confident that the GFCI would have prevented a more serious shock or injury, in the event that I had not been able to let go quickly.
quogueelectric
Senior Member
- Location
- new york
Yes I fully understand your positions
Yes I fully understand your positions
I spent most of the week reflecting on the answers while I was pulling moderator teeth out of my butt. Thanks for all of the input. I would though check to see if the ground was hooked up on your kitchen gfi. A lazy electrician might skip this part and make no mistake about it the MANUFACTURER requires the EGC to be hooked up if it is available This is my bigest mystery for this week. As far as being repeatable or testable There must be a thousand posters on this site who are capable of duplicating this circumstance and noone probably will because they dont believe the outcome so it goes by the wayside oh well we are all to busy. Maybe the next electrocution someone will take the time. Maybe it will be you in your kitchen or someone you love and care about I am just throwing out my experience you all can do what you want with it I can only try to warn people if they dont believe it or wish to explain it away you go girlfriend. It is what it is I can only try...........
Yes I fully understand your positions
I spent most of the week reflecting on the answers while I was pulling moderator teeth out of my butt. Thanks for all of the input. I would though check to see if the ground was hooked up on your kitchen gfi. A lazy electrician might skip this part and make no mistake about it the MANUFACTURER requires the EGC to be hooked up if it is available This is my bigest mystery for this week. As far as being repeatable or testable There must be a thousand posters on this site who are capable of duplicating this circumstance and noone probably will because they dont believe the outcome so it goes by the wayside oh well we are all to busy. Maybe the next electrocution someone will take the time. Maybe it will be you in your kitchen or someone you love and care about I am just throwing out my experience you all can do what you want with it I can only try to warn people if they dont believe it or wish to explain it away you go girlfriend. It is what it is I can only try...........
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quogueelectric said:
Why would we want to duplicate a test that has already been performed thousands of times? Do you have a copy of the 2008 NEC? Have you read 406.3(D)(3)? Why would the NEC allow us to install GFCI protection on an ungrounded circuit as allowed in this section if they would not work?
Here is some information from GOOGLE on how GFCI's work. Notice that they refer to hot to neutral imbalance, there is no mention of hot to ground. I know that your mind is made up and we are attempting to confuse you with facts, but hopefully you are open to learning something and not just trolling for posts.
"GFCI is much more subtle. When you look at a normal 120-volt outlet in the United States, there are two vertical slots and then a round hole centered below them. The left slot is slightly larger than the right. The left slot is called "neutral," the right slot is called "hot" and the hole below them is called "ground." If an appliance is working properly, all electricity that the appliance uses will flow from hot to neutral. A GFCI monitors the amount of current flowing from hot to neutral. If there is any imbalance, it trips the circuit. It is able to sense a mismatch as small as 4 or 5 milliamps, and it can react as quickly as one-thirtieth of a second.
So let's say you are outside with your power drill and it is raining. You are standing on the ground, and since the drill is wet there is a path from the hot wire inside the drill through you to ground (see How Power Distribution Grids Work for details on grounding). If electricity flows from hot to ground through you, it could be fatal. The GFCI can sense the current flowing through you because not all of the current is flowing from hot to neutral as it expects -- some of it is flowing through you to ground. As soon as the GFCI senses that, it trips the circuit and cuts off the electricity.
Here are some interesting links:
Ground Fault Circuit Interrupter Central
Ground Fault Circuit Interrupter Testing
Installing a Ground-Fault Circuit Interrupter
How Power Distribution Grids Work
Why is it that some appliance plugs have three prongs and others have only two?
How Wires, Fuses and Connectors Work"
- Location
- Illinois
- Occupation
- retired electrician
quogueelectric,
Don
I have no doubt that you recieved a shock, but that does not mean the GFCI was not doing its job. For the most part all a GFCI does is limit the duration of the shock. My guess is that because of the better path via the equipment grounding conductor the GFCI tripped much faster than it did when the EGC was removed. Remember that the GFCI is permitted to take up to 7.2 seconds to open the circuit at 5mA. You would drop the tool in a fraction of that time. With the EGC in place it may have tripped fast enough that you did not even feel the shock, but with a limited ground fault current path the time to trip goes up.
Don
- Location
- Illinois
- Occupation
- retired electrician
Haskindm,
Don
While it may trip that fast it is permitted to take up to 7.2 seconds to trip at that current level.
Don
Nikola Tesla
Member
sorry to burst your bubble on the history but....
sorry to burst your bubble on the history but....
It must first be reiterated that with extraordinary few exceptions no educated person in the history of Western Civilization from the third century B.C. onward believed that the earth was flat.
A round earth appears at least as early as the sixth century BC with Pythagoras, who was followed by Aristotle, Euclid, and Aristarchus, among others in observing that the earth was a sphere. Although there were a few dissenters--Leukippos and Demokritos for example--by the time of Eratosthenes (3 c. BC), followed by Crates(2 c. BC), Strabo (3 c. BC), and Ptolemy (first c. AD), the sphericity of the earth was accepted by ALL educated Greeks and Romans.
sorry to burst your bubble on the history but....
quogueelectric said:
It must first be reiterated that with extraordinary few exceptions no educated person in the history of Western Civilization from the third century B.C. onward believed that the earth was flat.
A round earth appears at least as early as the sixth century BC with Pythagoras, who was followed by Aristotle, Euclid, and Aristarchus, among others in observing that the earth was a sphere. Although there were a few dissenters--Leukippos and Demokritos for example--by the time of Eratosthenes (3 c. BC), followed by Crates(2 c. BC), Strabo (3 c. BC), and Ptolemy (first c. AD), the sphericity of the earth was accepted by ALL educated Greeks and Romans.
quogueelectric
Senior Member
- Location
- new york
yes they did
yes they did
I did a field test with my pet dinosaur and he told me it was flat so there dont fall off your edge
yes they did
I did a field test with my pet dinosaur and he told me it was flat so there dont fall off your edge
Charleds Burton
Member
GFCI Protection
GFCI Protection
It takes 5ma to stop your heart GFCI's are designed to trip at 3ma. YOU ARE STILL ALIVE. I did a live test too. I came in contact with hot to neutral on a gfci protected circuit and I felt it too but it tripped. You need toi take into consideration the leghth of the cord it does become a part of the load and slows the trip time but does not change the trip threshold.
GFCI Protection
It takes 5ma to stop your heart GFCI's are designed to trip at 3ma. YOU ARE STILL ALIVE. I did a live test too. I came in contact with hot to neutral on a gfci protected circuit and I felt it too but it tripped. You need toi take into consideration the leghth of the cord it does become a part of the load and slows the trip time but does not change the trip threshold.
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