Neat GFCI Experiment

[Scott F. Coslett]

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?
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[tdietrich1]

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.

[Marc D. Shunk]

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.

[Scott F. Coslett]

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?

[Bob Elliott]

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.

[Bob Elliott]

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.

[Marc D. Shunk]

Originally Posted by relliott

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.

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.

[Bob Elliott]

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.

[Marc D. Shunk]

Originally Posted by relliott

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.

[Bruce A. King]

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.

[Marc D. Shunk]

Originally Posted by bking

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

[Bob Elliott]

That I do not understand at all.

[Scott F. Coslett]

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

[cbuell]

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

[Richard L. Bennett]

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