Neat GFCI Experiment

A contractor friend of mine performed the following experiment and asked for my explanation this evening.

A 5 gal plastic bucket is filled with water. electrical cord (with insulation stripped from the ends) is placed into the water in the bucket. The lamp cord plug is then placed into a GFCI receptacle. Circuit is in a house that is easily 60-70 years old. My friend tells me the GFCI did NOT trip and the breaker did NOT trip and he wants to know why not.

Soooo what is the explanation ??

Here is my response. The circuit could be ungrounded, 2 conductor wire based on the age of the house. The GFCI didn’t trip because current is NOT unbalanced between the two lamp cord leads. The breaker didn’t trip because even though the water is a good conductor the leads had to have been far enough apart (I have no idea how far apart) that the electrical current could not overcome the resistance of the water.

And now the million dollar question…If I place my hand in the bucket should the GFCI trip?:shock:
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You pointed out something, there are so many factors, that is is possible it won’t trip. I’ve handled energized wires, and touched energized junction boxes and no shock. However, I do where OSHA approved electrical safety shoes too.

Why mess around, the experiment sounds dumb.

Water’s not that good of a conductor until it gets some crap in it. An ICDI was developed to detect water immersion, because GFCI’s suck at that.

Tom -

Dumb? Yes it is very dumb! (By the way, I certainly have no intention of duplicating the experiment or putting MY hand in the water!)

But it does make one think about grounding and how GFCI’s work. Isn’t this essentially why we test GFCI’s with the test button on an ungrounded circuit as opposed to using a circuit tester?

Marc I have heard in a class room, that water is actually an insulater and you get shocked because you are the closest thing that does conduct.
Of course I have since learned this applies to pure water with out the crap.

In a real situation I would think you are touching the load side and creating an Unbalance.I suppose if you could grab both sides at the same time a GFCI would not trip. Seems right.

There’s an electrical instructor (maybe Mike Holt?) that plugs a cord into the wall and puts the other bare end in his glass of water and takes a drink out of it.

So I am guessing he uses pure water.
I wonder what happens if something like his skin oil or tooth particles mix in the water some day.

My gut tells me it would take much more than that, like maybe a packet of salt. I’ll expect a full report from you on Monday, Robert. :stuck_out_tongue:

When they work on high voltage lines using a helicoter they clamp the hot wire to the frame of the helicopter to create a safer work environment.

Yeah, the company from that thing you watched on TV is actually right down the road from me. Agrotors, Inc.

http://www.youtube.com/v/Z3q9WdjD5wc

That I do not understand at all.

I’d like to meet the 1st guy to ever do that…maybe he would stick his hand in the bucket.

If you take an extension cord and strip the covering off both the hot and neutral a couple of inches apart (so they don’t short each other) and immerse it in water it will not trip the gfci. Put a light bulb in the female end and start adding salt with a salt shaker and watch the bulb glow and the the water heat. Believe it or not, and try at your own peril:D

Electrical 101

Two wires in the bucket is not a ground fault - it is just another light bulb - no fault

Three wires in a bucket of water might be a fault

Three wires in a bucket of water with salt will be a fault

One hand in the bucket is not a problem

One hand in the bucket with salt is not a problem

One hand in the bucket with salt is a problem if your other hand or feet are on something that is in contact with ground

GFCI’s trip when there is a current difference between ground and the neutral. GFCI give NO protection when a person is between the Hot and the Neutral. If that is you, your but is going to get warm

Draw it out on paper

rlb

Rich are you sure you do not mean between hot and neutral, since a GFCI does not require ground and is concidered to be a good way to protect your self when there is no ground.

Robert

Yes, I am sure GFCI will not trip with a person between hot and neutral – you are just another light bulb. It will save NO lives

If the person (you) are between hot and ground it will trip and you will live

This is one of the big miss understandings about GFCI’s – they will not protect you in all conditions. Dead is Dead if you are between hot and neutral and it does not take long

Just hope that you are also bare foot in the bath tub to cause the GFCI to trip

Sort of sounds funny to say that you should have you feet in water when working around electricty but in this case it is true and WILL SAVE YOUR AND YOUR LOVED ONES LIFE

Do it without your bare feet in the water and you will die

This is a once in a life time lesson that very few get to take again

Get in your bare feet when working down stream of a GOOD GFCI when the hot is hot. It will save your life if your wet feet are in contact with ground. Your will get your but warmed if not

rlb

I wish I could find the data but many years ago when it was Joe T and his gang of electrical inspectors yacking on Prodigy I did some testing of water conductivity looking at voltage across a 60w lamp and current. I had a white bucket with 2 12 ga probes immersed 6 in the water and 8" apart. Distilled water and a clean bucket did not conduct at all. My well water passed something like 150-200ma and the bulb glowed. If I used water off the dock (about 19PPT salt half what the ocean is) the bulb was bright and current was well over 400ma.

BTW all of this was on a GFCI protected receptacle.
The water in this case, without any ground reference or other path for current to leak away, was just “load”.

I can guarantee dropping a 3 wire extension cord in the water off the dock will trip a GFCI and this has been “tested” more than once. I assume a 2 wire cord would too but I haven’t got any. It is not the water per se that does it. The GFCI trips because the water is grounded, not sitting in a plastic bucket.

They are performing:

**Bare Hand Work – **A technique of performing work on live parts, after the employee has been raised to the potential of the live part. (2004 NFPA 70E)

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.

Rich this is off how stuff works.
If you sudenly grab the hot conductor the imbalance should be noticed , going by what I see in this information.
Suprised Joe T has not chimed in.