Will you feel a shock from a GFI receptacle ?

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acrwc10

acrwc10

Master Code Professional
Location
CA
Occupation
Building inspector
I was on the job today and one of the carpenters had his hole hawg plugged into a GFI receptacle. When he was changing the drill bit he had one hand on the drill chuck and with the other hand he touched a small nick in the cord that had a single strand hanging out of it. He jumped around a little and then dropped the drill. The GFI receptacle never tripped. I took apart the cord cap just to be sure it was not a ground / neutral reverse on the tool. And the GFI was wired correctly and the test button made it trip. So I guess I have 2 questions , one should you be able to feel that much of a jolt before it shuts off/ trips and two ( and this seems obvious ) could the jolt have been under the 5MA threshold to cause a trip and still sting ? I'm not going to stick my hands into one to find out either , at least not on purpose. And yes I replaced the receptacle just to be sure it was safe.
 
Yes and yes.

A GFCI can not open the circuit until it senses the ground fault. By the time the circuit opens the person has felt it.
 
Did you ever try the test button on the receptacle? That should give a good indication if the GFCI is good or bad.
(Although I think changing the recept. even if it tested good was the safe thing to do.)

I think it could have been below the 5 ma threashold too.
 
Last fall my pond heater broke and I didnt notice, I reached in the water to clean the filter and got nailed pretty good, the GFCI tripped (Saving my stupid butt) and I was suprised how hard I got hit even with the GFCI.
 
acrwc10 said:
. . . he touched a small nick in the cord that had a single strand hanging out of it.
Click to expand...
I would try a solenoid tester between the drill body and that strand. If that trips the GFCI (which it should), then he jumped too fast.
 
acrwc10 said:
And yes I replaced the receptacle just to be sure it was safe.
Click to expand...
Have you asked carpenter to test it since you changed the receptacle or has he already fixed his cord? Perhaps an ammeter between him and the cord would give you some good data.:grin:
 
Almost , all anyone could want to know about GFCIs can be found ion this one article ,.I think
http://ecmweb.com/mag/electric_think_gfci/
It's also important to remember that a GFCI does not limit the magnitude of the fault current. Instead, it limits only the duration of the fault. Therefore, it's possible for a person to receive a shock on a circuit protected by a GFCI.

The magnitude of any fault current is limited by the supply voltage and the impedance in the fault circuit. In most electric shock scenarios, the person is the principal impedance source, and the magnitude of the shock can therefore vary considerably, depending on the condition of the skin, contact area, body weight, and current path through the body.
Click to expand...

Kneeling on the moist ground with a hand in a fish pond ,..Ill guess a pretty healthy size ,.. and ,..whammy!!:)
 
acrwc10 said:
So I guess I have 2 questions , one should you be able to feel that much of a jolt before it shuts off/ trips and two ( and this seems obvious ) could the jolt have been under the 5MA threshold to cause a trip and still sting?
Click to expand...

When I was in engineering school (1969 range), my roommate was fascinated by these new GF thingies ... we built the differential transformers and electronics to drop out a relay. We also played with (stupidity of youth) series resistors and our worthless bodies to see what we could feel. I remember well that 1mA was not comfortable. He setup his test bench at home with his 2mA GF boxes.
 
When the poor carpenter touched the loose strand with one hand and the chuck of the stupid holehawg was "grounded" through the neutral, then the GFCI wouldn't have sensed a voltage imbalance and thus would not have tripped.
He should get rid of that dangerous device.
~Peter
 
"If it's got a bad cord, why not just replace the cord?"
Because it's a HoleHawg. It doesn't have a clutch. When the bit hits a nail, it stops and the motor starts spinning. This reaction once broke my glasses and another time cut my lip. I don't like them.

Note: I just noticed that the original poster inspected the cord cap and it was properly wired, so forget my original speculation.
~Peter
 
peter said:
"If it's got a bad cord, why not just replace the cord?"
Because it's a HoleHawg. It doesn't have a clutch. When the bit hits a nail, it stops and the motor starts spinning. This reaction once broke my glasses and another time cut my lip. I don't like them.

Note: I just noticed that the original poster inspected the cord cap and it was properly wired, so forget my original speculation.
~Peter
Click to expand...

So use your hands instead of your teeth. :grin:

I've had one for the last 15 years. Once you get used to the power, you can plan for such occurances.
 
When GFCI's first hit the market I bought a GFCI tester and tested a few GFCI's, I told the guy I was with these things are human safe and grabbed the ungrounded conductor and ground. YEOW>>>>>>>>>>>>>he was laughing his tushie off calling me every word for stupid he could think of.

I'd like to think I am wiser now, but there is no proof of that.
 
When I was younger ,.. and a bit lighter,.. I worked for a guy who had one of these pigs with a lock on feature , after market installation ,..if I remember correctly ,.. Well one day it lifted me up of the step ladder I was on and I started to wind around,..somehow I let go before my wrists snapped ,.I fell to the floor ,.. while backing away ,.the 3/4 " rigid pipe handle broke as this baby cranked around into the joists ,.. Then after a few more revolutions the cord detached ,... I hate them flipping things ,..call me a girly man if you must ,...them things is mean and nasty.
 
M. D. said:
..call me a girly man if you must ,...
Click to expand...

hans_franz.jpg


"You are all girly-men!"​
 
acrwc10 said:
I was on the job today and one of the carpenters had his hole hawg plugged into a GFI receptacle. When he was changing the drill bit he had one hand on the drill chuck and with the other hand he touched a small nick in the cord that had a single strand hanging out of it. He jumped around a little and then dropped the drill. The GFI receptacle never tripped. I took apart the cord cap just to be sure it was not a ground / neutral reverse on the tool. And the GFI was wired correctly and the test button made it trip. So I guess I have 2 questions , one should you be able to feel that much of a jolt before it shuts off/ trips and two ( and this seems obvious ) could the jolt have been under the 5MA threshold to cause a trip and still sting ? I'm not going to stick my hands into one to find out either , at least not on purpose. And yes I replaced the receptacle just to be sure it was safe.
Click to expand...


GFCI's are only designed to HELP prevent fatal shocks. The were never designed to ELIMINATE them. They only trip on a line to ground fault and not on a line to neutral fault.

They also must see an imbalance of current, so...... if you are the path to ground.... you will get a shock.
 
roger3829 said:
GFCI's are only designed to HELP prevent fatal shocks. The were never designed to ELIMINATE them. They only trip on a line to ground fault and not on a line to neutral fault.

They also must see an imbalance of current, so...... if you are the path to ground.... you will get a shock.
Click to expand...

If there is a path to ground (A person or anything else) there will be an imbalance and the GFCI will trip.
 
zog said:
If there is a path to ground (A person or anything else) there will be an imbalance and the GFCI will trip.
Click to expand...
But only after the person has been shocked and at the low end of the range the GFCI is permitted to take up ~7 seconds to trip.
 
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