GFI receptacles

[LarryFine]

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're luckier than you realize. A GFCI would see any and all line-to-neutral current as normal load. You apparently conducted enough current to earth (or the EGC) outside of the two circuit conductors to trip the GFCI.

 

[George Stolz]

It takes 5ma to stop your heart GFCI's are designed to trip at 3ma.

Actually, the values to stop a heart are higher than that. Click here for an old discussion on this, towards the bottom of the page Roger provided a link to a site with a table of the consequences of different levels of current through the body.

I think GFCIs are designed to trip at 5mA, but that's just going off my memory.

 

[iwire]

I think GFCIs are designed to trip at 5mA, but that's just going off my memory.

Unusual but true...this info is actually contained in a FPN in Article 100 under GFCI. :smile:

"Class A ground-fault circuit interrupters trip when the current to ground has a value in the range of 4 mA to 6 mA"

 

[dab]

if the purpose of a gfci is toj protect persons from being electrocuted to death, why wouldn't it work. if you became the third conductor and grounded out a fault it should trip the gfci.

 

[roger]

if you became the third conductor and grounded out a fault it should trip the gfci.

And it would if there were more than around 5 ma of current flowing through you as the third conductor.

Roger

 

[augie47]

test

test

gentlemen, I believe what we have here is the ultimate classic case of: "don't confuse me with the facts, my mind is made up".

Difficult to beat without professional help.

 

[iaov]

Gfics

Gfics

If you take a look at a schematic of a GFCI you will see that they do not need an EGC to work. I am intrigued by the fork in the socket method of testing,and might even pay money to watch, however I think I will continue to use my Vol-Com "Wiggy" to trip these circuits.

 

[tom baker]

A GFCI must have a ground to test properly, but not to function.
QUOTE]
No, it does not. The GFCI test button inserts a resistance from hot to neutral thru the torroid coil creating the imbalance. The EGC is not needed to test it with the button.

 

[tom baker]

A gfci receptacle needs to be connected to a ground wire to work properly.

I would like to suggest to you to go to the IAEI website, and purchase a book by Earl Roberts called Undercurrents and Overcurrents. It gives the history of the GFCI and how it works.
GFCI's are very safe as they don't require the EGC to work.
If that was not the case, why does the NEC allow a 2 wire non grounded recp to be replaced with a GFCI marked no equipment ground?
However, if you disagree, why submit a code change, the forms for the 2011 NEC are now available, to require an EGC for every GFCI application.

 

[andinator]

I just read the book and alot of things became much clearer for me.

 

[cowboyjwc]

Wow, I only walked out of the room for a minute.

1. The way it was explained to me by a very brilliant man was, "there's a reason they call it the theroy of electricity".

2. There is a warning lable on your GFCI testers that tell you not to use on a two wire system as there is a potential shock hazard.

3. Preception current: <1ma, Let go current: 6ma-99.5% of all men, women and children, 10ma-98.5% men, 60% women, 7.5% children, 20ma-7.5% men, 0% women & children Ventricular Fibrillation: As low as 60ma

.002 amps= mild sensation of electrical shock
GFCI's operate at .004-.006 amps
.008 amps= painful shock

Lowest impedance- chest to left hand
Most vulnerable time- 1st 1/7th of cycle

Physiological effects of ground faults depends on: Voltage, current, AC vs DC, frequencies, time, waveform, path, body.