Electricity under water

I built a lake home for some clients and later installed an underground drop to a pedestal with a 240 volt disconnect (exactly like an AC disconnect). From there, the people who built the dock tied into the disconnect to run wire out to the dock.

Then the rains came. The lake rose almost 35 feet in a matter of weeks. More rain. The lake rose to flood stage and submerged the pedestal. Yet power remained to the dock. The pedestal was under about 15' of water, yet did not trip the breaker at the main service. The owner called me and asked if this was dangerous and I said yes, turn off the breaker at the breaker box, which he did.

My question is: why did the breaker not trip when the disconnect was submerged? It is not waterproof by any means.

Reply to
Robert Allison
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OOPS! meant to post this to alt.home.repair!

If any of you have the answer, though, let me know.

Reply to
Robert Allison

Water doesn't conduct well. In fact, one method of measuring water's purity, is by measuring how badly it conducts electrical impulses. One of the reasons the human body conducts reasonably well, is the saline content in our bodily fluids, Mandrake. (Obscure reference intended)

r
Reply to
Robatoy

Mythbusters did a segment on tossing a toaster in the bathtub and see if you could be electrocuted. They found some current between the toaster and the drain, when the drain was metal and grounded; otherwise nothing. I am surprised there was even that; the toaster neutral is a rather better ground than anything else; why would current go through a person instead?

Oh, to answer your question; without dissolved salt; water does not conduct electricity. All the rain was distilled water.

Reply to
Toller

You have a nice pure lake there. "Reference Data for Radio Engineers" classifies distilled water as an insulator, although as insulators go, it's a very poor one. 10^6 ohm-cm

Ionized ("impure") water is more highly conductive, but how much so is difficult to predict. Rest assured that some conduction was going on, it was just less than the trip point of the breaker. At least the load was water-cooled. :-)

Reply to
Wes Stewart

Not unusual ... when my own house flooded in 2001, and before I could turn the service off, all receptacles under water were still hot and the only ones that tripped were the GFCI in the garage ... which brings up the point that your circuit above ideally should be GFCI breaker protected, for the outdoor purpose stated.

As the builder you might want to consider springing for one after the fact, while you still can. :)

Reply to
Swingman

We originally installed a GFCI. The owners got real tired of walking the 600 feet to reset the breaker. It tripped about every 10 minutes. Replaced it with a different GFCI. Tripped about every 15 minutes. Replaced with standard. Won't even trip when underwater.

My electrician checked the drop and found no problems. He said that on that long of a run, a GFCI is not a good solution due to constant tripping of the breaker. I have found that to be true with several other applications, also.

The way it is set up, there is a 50 amp breaker protecting the line to the pedestal, then to the dock. On the dock is a subpanel with breakers protecting everything else.

Reply to
Robert Allison

That's not true. *Pure* water is a very poor conductor of electricity -- but having *anything* dissolved in it (not just salt) makes it conductive.

What, you think all the water in the lake got there directly as rainfall? None of it was runoff? And nothing ever dissolved in it afterward?

Reply to
Doug Miller

Way back when, long before now, hopefully long enough ago for the statutes of limitations to expire, we used to do what we called "telephoning fish". We did this using the generator from the old crank telephones. Drop a weighted wire to the bottom and another wire that we just stuck in the top of the pond, stream, creek, etc. Crank on the handle, and fish would float up. This was fresh water. It seemed to conduct the current well enough to stun the fish.

Reply to
Robert Allison

Cool! I've heard of that before, but never saw it done. How big a fish can you stun this way? And how far away from the apparatus?

Reply to
Doug Miller

It stuns every fish around no matter what size as far as I can tell. We were getting catfish about 10-20 pounds. The others we just left in the water and eventually they would swim off.

It just gets the ones close by, I guess within maybe a 4-5 foot radius of the area between the wires. It is really hard to know for sure about that, because this was not clear water. It was pretty murky.

I have done the same thing using a car battery and an old coil from a chevy truck. If you have ever touched the spark plug wire and gotten zapped, then you know what they can put out.

You know that this is illegal, right?

Reply to
Robert Allison

Damn!!

It'd be fun to experiment in a clear lake. I've fished in a few inland lakes in Michigan's Upper Peninsula where the bottom was clearly visible at twenty feet. *Very* easy to tell where the fish are.

Oh, yes. And I would never ever try anything like this. Except maybe for experimental purposes.

Reply to
Doug Miller

Make sure that you carry the test far enough to decide if the method changes the taste of the fish.

And I don't know about this for sure, cause I have never tested it, but everyone used to say this: Don't try this in an aluminum boat.

Reply to
Robert Allison
[snip]

Do they also say to get out of your car during a lightning storm?

Reply to
Wes Stewart

A quart Mason jar with screw on lid, a rock inside to sink the jar, some carbide (once used by coal miners for their lamps), and a little water.

Place rock in jar, add carbide and water, screw on lid, throw in water and watch it sink.

Pretty soon, Mason jar will explode and fish will rise to surface, belly up.

Time to start dinner.

Lew

Reply to
Lew Hodgett

Very little is dissolved in rainwater run-off. There may be a huge amount of dirt and stuff in suspension, but dirt in suspension is no different from a log floating by.

The only thing that COULD dissolve in the run-off was stuff put down since the last rain.

Reply to
HeyBub

Makes sense to me. Guess that ancient fiberglass canoe is still good for something...

Reply to
Doug Miller

Hmmmm.... So you think that there isn't much dissolved in lake water, eh? Try an experiment: dip a quart jar full from your nearest lake, then measure the electrical resistance.

Reply to
Doug Miller

So none of the Ca/Mg/Mn/K/etc. salts in some of that dirt and stuff manages to dissolve at all, huh? Interesting hypothesis...

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Reply to
dpb

Water apparently conducts enough to allow for electrolisys (sp?) to occur in rivers and lakes. That is why outboard motors and I/O outdrives (as well as the boats themselves on inboards) have anodes attached. These are made from a metal more subject to being eaten up than the metal on the boat or motor. I believe that for fresh water the anodes are made from magnisium. These anodes are eaten away from fairly natural electric charges in water, but get eaten much faster near commercail docks with electric service. That is usually due to some doofus having his boat connected to the electric service with some type of power leak somewhere on the boat that allows a little charge to find its way to the water. That reminds me, I need to check the ones on my boat which are probably due to be replaced soon ;-).

Dave Hall

Reply to
Dave Hall

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