revisiting the gfci

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Hobbyman2
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revisiting the gfci

Post by Hobbyman2 »

I had forgot I was going to explain how a gfci does not all ways protect one from shock , I think the drawing may help in my description of how you can still be shocked even with a gfci and it will not trip .
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I tried to flip it but its still upside down lol
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Re: revisiting the gfci

Post by DLB »

Hobbyman2 wrote: Wed Jan 26, 2022 12:13 am I had forgot I was going to explain how a gfci does not all ways protect one from shock , I think the drawing may help in my description of how you can still be shocked even with a gfci and it will not trip .
The drawing does not help me understand it. I think the drawing depicts getting shocked on neutral upstream of the GFCI device. But I'm thinking this is not what you mean, because the other drawing shows no shock on hot upstream of the GFCI, which is not true. Ultimately I'm lost. GFCI interrupts the circuit downstream only by monitoring for unequal current between hot and return lines. It does not prevent shock. If the GF path is through a human that is a shock. If the amplitude of the shock is high enough the GFCI will remove power from the circuit and stop the shock, not prevent it. Getting shocked on neutral is possible but unlikely given a proper electrical installation because neutral is supposed to be near the same potential as ground, rule of thumb is 2 to 3 VAC max. But the GFCI device should still protect as long as the GF is downstream from where it is being monitored and exceeds the threshold.

If the GFCI device is an outlet receptacle it generally offers downstream device protection optionally depending on how it is connected. It always provides GF protection for things plugged into the receptacle.

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Re: revisiting the gfci

Post by Hobbyman2 »

Thanks David
If you look at the switch in the one it is in the off position , touching one leg at a time from the fed wire you should not be shocked , normal , unless you are grounded touching the hot wire alone will not result in a shock , touching both terminals will / can bypass the GFCI , in order for the GFCI to work the anomaly needs to be processed through the GFCI ,plugging something in the GFCI provides over current protection , at that point the GFCI should react to a overcurrent anomaly , in the other the switch is on and a light bulb is using current , touching a terminal will result in a shock regardless of being grounded . the GFCI will not react as it reads extra current anomaly as a point of use . disconnect the light bulb and touch the hot wire terminal and again no shock unless grounded . the only way a GFCI that I have purchased works is if the over current anomaly passes through the GFCI protection device . JMO A GFCI breaker is much safer than a GFCI plug but still only offers limited protection .
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Re: revisiting the gfci

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My point was you can be electrocuted / shocked with out being grounded even in a GFCI protected circuit . a GFCI only reacts if there is a ground fault passing through it .
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Re: revisiting the gfci

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Screenshot_20220126-122530_Gallery.jpg
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I believe the statement before was you can not be shocked when using a GFCI protection device and this is not the case , in the situation in this picture not even a GFCI breaker will protect from a shock hazard . shock can be on either down current or from the feed side . or touching the terminal or wire one at a time . the same thing will occur in a series circuit .
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Re: revisiting the gfci

Post by DLB »

I agree. The NEC is consistently expanding the areas where GFCI is required, but the pattern includes the potential of a ground path through a human.

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Re: revisiting the gfci

Post by beeg »

Doesn't a person have to be a path to ground, to be electrocuted ? No ground,no flow of electricity.
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Re: revisiting the gfci

Post by jsburger »

beeg wrote: Wed Jan 26, 2022 6:42 pm Doesn't a person have to be a path to ground, to be electrocuted ? No ground,no flow of electricity.
What is your definition of grounded? You don't have to be earth grounded, only grounded in relation to the supply of the electrical current.

Also electrocuted and shocked have two different meanings. If you are electrocuted you are dead. If you are shocked you are not dead but you may be seriously injured depending on the severity of the shock.
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Hobbyman2
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Re: revisiting the gfci

Post by Hobbyman2 »

jsburger is correct , if you happen to be in a puddle of water and this happens , guess what ,, the GFCI is worthless . When I was in class .. many many years ago , our instructor told us a story about his mentor , he was installing a disposal under a sink, it was his last job .according to him thats where they found his mentor , the situation he got into was the same as above only the circuit was gfci protected with a GFCI breaker and there was water under the sink where he was laying

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Last edited by Hobbyman2 on Wed Jan 26, 2022 9:48 pm, edited 1 time in total.
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Re: revisiting the gfci

Post by Hobbyman2 »

beeg wrote: Wed Jan 26, 2022 6:42 pm Doesn't a person have to be a path to ground, to be electrocuted ? No ground,no flow of electricity.
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There is a difference between a serries circuit and a parallel circuit , in the last picture there are two types of circuits, the lights are in parallel the stick person is in a serries . if the light bulbs were unscrewed the risk of shock would decrease , the current flows through the light bulbs and through the stick person because he is in a direct path .
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