While we're on the topic - which I find fascinating - I think you'll all agree a toaster in the bathtub is a more likely hazard than an outlet across a flooded room. But still, if you're not actually touching the conductors, and you're no better grounded than anything else in the water, is a toaster in the tub really a guaranteed electrocution like they show in the movies?

The drain is the ground. If you're in the wrong place at the wrong time, yes--you could get a severe shock from a toaster in the bathtub.

 

Tap water is pretty good about not conducting well, but DI water is the holy grail. It's even better than distilled water. Like the previous example, you can move the conductivity of a glass of DI water past the conductivity of a glass of tap water with a dirty finger.

Trying to make water pretend it's a wire seems absurd to me. You have to consider cross section to do that.

 

Tap water is pretty good about not conducting well, but DI water is the holy grail. It's even better than distilled water. Like the previous example, you can move the conductivity of a glass of DI water past the conductivity of a glass of tap water with a dirty finger.

Trying to make water pretend it's a wire seems absurd to me. You have to consider cross section to do that.

What do you mean by "The Holy Grail"? Distilled water is not conductive at all, tap water is significantly more conductive than Distilled water. The latter actually works like an insulator.

Tap water conducts (somewhat) well because of its impurities (minerals from the earth and pipes). Distilled water is pure H2O, and there are no free electrons in the chemical structure to allow current to flow through it.

Matt

 

Tap water is pretty good about not conducting well, but DI water is the holy grail. It's even better than distilled water. Like the previous example, you can move the conductivity of a glass of DI water past the conductivity of a glass of tap water with a dirty finger.

Trying to make water pretend it's a wire seems absurd to me. You have to consider cross section to do that.

My tests were to confirm that our acceptance tests in the wire & cable plant I sed to work in were valid. We would dunk reels of wire into a pit full of water and use a megger to measure insulation resistance via the water. I became suspicious of the method when one day I megger'd the water alone and found it to be a few megohms from one side of the pool to the other, and I assumed that to get a reliable measurement of insulation resistance would require the surrounding fluid to be as close to zero ohms as possible.. So I launched a witch hunt. My final conclusion was that the test was valid since the megger was accurate to terraohms and the IR spec was gigohms.

During the course of my experiments I wanted to see just what it would take to make water as conductive as possible. I tried several things. Salt seemed to make the most conductive water, followed by baking soda.

 

What do you mean by "The Holy Grail"? Distilled water is not conductive at all, actually works like an insulator.

Consider that I worked in the room next to a water quality laboratory. If distilled water is, "laboratory grade" for not conducting electricity, why did the lab go to the expense of maintaining a deionizing tank instead of just using an electric heater to distill some water?

Either I'm assuming too much or you know something they didn't know.

 

...yes--you could get a severe shock from a toaster in the bathtub.

No doubt. But do you agree that the typical movie treatment is farfetched? Sparks, whole-body muscle spasms and contractions, imminent death. I wonder how it became "common knowledge" that this is what happens.

 

Consider that I worked in the room next to a water quality laboratory. If distilled water is, "laboratory grade" for not conducting electricity, why did the lab go to the expense of maintaining a deionizing tank instead of just using an electric heater to distill some water?

Either I'm assuming too much or you know something they didn't know.

Sorry #12, I was comparing Distilled Water to Tap Water. Distilled water is far less conductive, and the wording of your post confused me a bit, but I see now that we agree with one another.

No doubt. But do you agree that the typical movie treatment is farfetched? Sparks, whole-body muscle spasms and contractions, imminent death. I wonder how it became "common knowledge" that this is what happens.

Absolutely. Most movies over-dramatize things like that. Sparks are especially used to make the shot look more intense.

 

Strantor, I'd like to pick your nits a bit. When "Salt" is used as a chemical term, it means lots of different ionic compounds. I assume you were talking about table salt, NaCl, Sodium or sodium something or other reacted with hydrochloric acid. There are lots more salts, and some of them might be better at producing conductivity than NaCl. Problem is, I don't think there are any real chemists here (including me). I bet this is googlable...highest conductivity salt solution.

Here is a partial answer. Aluminum sulphate is the highest conductivity on this page:http://answers.yahoo.com/question/index?qid=20091007080443AACraFS

Point is, I bet you were limited in the different substances you had available to make salt solutions and there is probably something better than NaCl.

 

Correct, I was using table salt. Same as you find in the ocean, which is why I chose it, other than that's the only kind if salt I had .

Another strange finding was that salt water seems to have some semiconductive property. A cup of heavily salted water might read a few kohm with the fluke (uses one volt) but when introduced to 12 v power no current limit, it may pass 3A or more. I suspect it has to do with surface area of the probes, but that can't explain it entirely.

 

While we're on the topic - which I find fascinating - I think you'll all agree a toaster in the bathtub is a more likely hazard than an outlet across a flooded room. But still, if you're not actually touching the conductors, and you're no better grounded than anything else in the water, is a toaster in the tub really a guaranteed electrocution like they show in the movies?

I always wondered if they used a mouse in a bathtub, and then a human in a bathtub........throwing in a toaster.......I don't think either one would be killed.
Too much water to absorb the electrons, right?

 

Correct, I was using table salt. Same as you find in the ocean, which is why I chose it, other than that's the only kind if salt I had .

Another strange finding was that salt water seems to have some semiconductive property. A cup of heavily salted water might read a few kohm with the fluke (uses one volt) but when introduced to 12 v power no current limit, it may pass 3A or more. I suspect it has to do with surface area of the probes, but that can't explain it entirely.

So, what happens when I push down the "Toast level" on high or rig it, so it won't pop?

 

Consider that I worked in the room next to a water quality laboratory. If distilled water is, "laboratory grade" for not conducting electricity, why did the lab go to the expense of maintaining a deionizing tank instead of just using an electric heater to distill some water?

Either I'm assuming too much or you know something they didn't know.

Most of the HV equipment I work with has a limit of 5 Megaohm-cm for DI water purity. They normally run above 10 with new filters. The pure distilled water used to refill the DI systems might be 2 Megaohm-cm at best. I've actually had large DI leaks in live equipment controllers and power supplies with no negative effects after a good blow-down to remove the moisture and a heat treatment to bake out boards. Ultra-pure DI water has some pretty strange dielectric constant properties under high voltage stress (100kV+) as the water molecules are not symmetrical and can form pockets of isolated charge structures within a large volume of water creating a fluid capacitor with a significant amount of energy stored in it.

 

What do you mean by "The Holy Grail"? Distilled water is not conductive at all, tap water is significantly more conductive than Distilled water. The latter actually works like an insulator.

Tap water conducts (somewhat) well because of its impurities (minerals from the earth and pipes). Distilled water is pure H2O, and there are no free electrons in the chemical structure to allow current to flow through it.

Matt

My understanding, which is pretty minimal and may well be wrong, is that distillation and deionization are basically methods of removing somewhat different things. Deionization removes ionized substances, but not impurities that are not ionized. Distillation removes most impurities but anything, particularly organic substances, that have similiar boiling points may not be removed very well. So to get really good, pure water, you distill it and then deionize it.

One thing I wondered was whether lowering the pressure at which you are distilling the water would have different effects on the boiling points of different solutes. If so, then you could conceivable improve the results by going through multiple stages of distillation and doing each one at different pressures (positive and negative, potentially).

 

Shucks, you don't even have to be at home to get zapped.

East Village Woman Was Electrocuted on Street With Metal Plate, Medical Examiner Says

 

I always wondered if they used a mouse in a bathtub, and then a human in a bathtub........throwing in a toaster.......I don't think either one would be killed.
Too much water to absorb the electrons, right?

I don't think the water absorbs electrons. I think that either mouse or human would have little chance of being electrocuted if the toaster were submerged in the water beside them. But I'm not willing to test that theory . Human holding previously submerged toaster, standing in bath water, different story.

Another thought on the human vs mouse vs toaster topic; human bathing in tub, which has more likelihood to cause death to the human if dropped into the bath; a mouse or a toaster?

 

I don't think the water absorbs electrons. I think that either mouse or human would have little chance of being electrocuted if the toaster were submerged in the water beside them. But I'm not willing to test that theory . Human holding previously submerged toaster, standing in bath water, different story.

Another thought on the human vs mouse vs toaster topic; human bathing in tub, which has more likelihood to cause death to the human if dropped into the bath; a mouse or a toaster?

There is no doubt that if you are in the bathtub and a live toaster is thrown in, you WILL be electrocuted. The Mythbusters actually did a good job of showing that (I normally don't use the Mythbusters as a source anymore, but this myth was tested back when they were doing a good job of examining the science behind it, not just trying to replicate the effects).

 

Someone posted some time ago, about energized pipes in their shower stall... and how they felt a jingle when touching the showerhead pipe ??

Seems that would be absolutely deadly without fail...

 

His last name wasn't Himmler by any chance??
Max.

 

Deionized water is water free from ions, and therefore will not conduct. Distilled is free from all impurities (Theoretically), and also will not conduct.

You can add table sugar to distilled water and make it deionized water. It still wont conduct, but it's not pure either.

I imagine that lab-grade distilled water and supermarket grade are a little different in terms of quality.


Now, if the resistance of water is so high, and your body by comparison so low, then wont there be a voltage difference across your body if you're submerged? IE, at your feet the voltage is 100, but because of the resistance of the water it is only 20v at your head. Now you become the low resistance path for 80v.

 

There is no doubt that if you are in the bathtub and a live toaster is thrown in, you WILL be electrocuted. The Mythbusters actually did a good job of showing that (I normally don't use the Mythbusters as a source anymore, but this myth was tested back when they were doing a good job of examining the science behind it, not just trying to replicate the effects).

I don't remember that episode. I still don't understand why you would get shocked. Why does the current have any incentive to travel outside the toaster enclosure once it's dunked? Why would it decide to travel through the bath water to the grounded drain, when it has a closer, lower resistance path to ground right inside the toaster enclosure, where the copper neutral wire is? I'm not saying that "all the current takes the lowest resistance path to ground" but most of it does. I would think that the current from the live wire in the toaster to the drain would be small, and that the water itself is higher resistance than your body, so the voltage drop across your body should be small.

Do you remember when they did the experiment? I'd like to look it up in netflix.