Comments on: Episode 19: Killer Quicksand

By: Enlade

Enlade — Mon, 09 Aug 2010 22:24:43 +0000

I’m not exactly sure I understand what you are trying to test with your tub experiment. As we all know if you put yourself into a circuit that has enough amperage to kill you then you will probably die. So, your tub experiment seemed like a lot of hoopla to test that obvious statement. You might as well have hooked your sensor up to a car battery and then hooked it up to a doughnut. Conclusion, one will hurt you and the other won’t. If you are in a tub and something happens that puts you into a circuit with enough amperage to kill you then you will likely be killed. But that is the same anywhere you might do such a thing. If you stick your fingers into a house socket you might be killed. If you are on the moon, in a tub, at the bottom of the ocean, and you do the same thing then nothing has changed. Its the same result no matter where you are. If you stick your finger into a doughnut then you will be fine. Unless its someone elses doughnut which might get you a sock in the nose, but you won’t die from electrocution. Again, doesn’t matter that you are in a tub, on the moon, or at the bottom of the sea. The results of your tub experiment will be directly dependent on whether you put your sensor in the circuit or out of the circuit. You are simply testing where you put your tester and that doesn’t seem like a useful experiment to me.

By: Enlade

Enlade — Mon, 09 Aug 2010 21:34:52 +0000

I must agree with the other comments. The movies I remember would show a bubbling quicksand (usually with a gaseous fog hiding the quicksand from the unsuspecting movie star…possible from the gas). So, I don’t see how you can just ignore the likelihood that there is some gaseous mixture in the soil. I think that what you proved was that processed sand and filtered tap water one could not kill a movie star. Then again, given the intelligence of your average movie star these days…boy that’s another episode. Dumb blonds got some competition there.

By: Brad

Brad — Thu, 15 Jul 2010 14:38:36 +0000

As FHA compliance inspector I have read the above comments regarding the Ground Fault Circuit interrupters, GFCI’s, with interest. There is some very good information and not so good information listed by the participants. The Mythbusters do a good job at providing basic information in an entertaining way, but they cannot address all the different combinations of conditions that appear in the million of households across our country. What the above comment fail to address is the concept of probability. If it was easy to be electrocuted while in contact with water then we would see many more electrocutions nation wide. We do not see that many electrocutions because the conditions to be electrocuted must be just right, the odds must be against you. Many of the commenter’s cite ohms law but fail to see it as an interrelated system that under the proper conditions can combine to cause 30 milliamps to travel across the heart. This approximate threshold will cause Fibrillation and ultimate death. The conditions must be exactly right.
I would submit that most electrocutions in a tub would have something to do with physically touching the appliance that was dropped in the tub and the bather touching some other grounding conductor at the same time. Any metal component that can be reached while in the tub could possibly complete a circuit through the body and complete the circuit through the heart. It is usually a combination of issues; a wound on the skin that greatly reduces the resistance of the body, additives to the bath water that can reduce resistance, frayed cords and defective appliances, missing or improper bonding of the water supply system, defective GFCI’s can all be contributing factors. Everything must occur in the proper order to become lethal and these conditions can be difficult foresee. However, when these factors combine in the proper order then they can become quite lethal. The subject of electrocution is complicated and cannot be covered in a few minutes on TV. One thing is for sure, when you are wet and you come into contact with electricity then you GREATLY increase the probability of something bad happening.

By: Taz

Taz — Mon, 28 Jun 2010 16:47:53 +0000

I can’t believe how many morons are posting here claiming they are experts. It’s sad really. Especially you, Steve. Could it be that it’s a rare occurrence nowadays because basically EVERY bathroom in this country has GFCI outlets and EVERY hairdryer has a GFCI plug? Why don’t you google ‘bathtub electrocution’ and see what comes up. Call the NY Times and tell them that their story from 1984 about the 2 little girls electrocuted when a hairdryer fell into the tub (BEFORE GFCI’s) is an old wive’s tale. You f’n moron. Why don’t you give it a shot if you’re so sure. Make sure you run an extension cord into the bathroom from a non-GFCI outlet and use something without a GFCI plug. The world could use one less idiot like yourself.

Electricity will go wherever it wants through a conductive medium. It doesn’t matter if it’s silver or salt water as long as it’s all connected. If it’s a radio in a salty bath, yes, most of the power WILL go directly from hot to neutral. But it will ALSO seek ground to the metal drain. If that happens to be through YOU,(ie: you have your foot on the drain), and your resistance is low enough to allow sufficient current to flow through your heart, you are dead.

As little as 7 mA for 3 seconds will kill you. Not 500mA, not 900mA (.9A), 7mA. A jolt of 25-50mA will stop your heart in less than a second. That is the reason GFCIs are required to trip at a 5mA imbalance within 25mS.

For those of you ‘experts’ who have obviously never met Mr. Ohm or been briefed on his law:

At 125V, to allow 7mA to flow requires a resistance of 17857 ohms. 25mA requires 5000 ohms, and 50mA requires 2500 ohms. Now listen carefully.. The average ‘dry skin’ resistance of a human is 1500 ohms. If we divide 125 by 1500, we get .083 or 83mA. That’s MORE than enough to kill you when you’re DRY. When you are wet, your resistance can drop to as low as 300 ohms. So again we divide 125 by 300, and this time we get .417 or 417mA (almost half an amp). That is TEN TIMES the current needed to kill you. But far far less than would be needed to trip a regular circuit breaker.

Now obviously this takes into account the fact that MOST bathtubs are grounded through plumbing. It DOES NOT account for plastic non-conductive plumbing or a plastic tub, and what would happen in the water with no alternative path to ground through the drain. In theory, you would NOT be electrocuted. It would also, in theory, NOT trip a GFCI, because there is no alternative path to ground to cause the imbalance which would cause a GFCI to trip. That would be an interesting thing for them to test in a revisit.

By: Steve

Steve — Mon, 14 Jun 2010 02:39:18 +0000

First let me say that I have been an Electrician for 30 years. Electricity takes the PATH OF LEAST RESISTANCE..
Inside of the “appliance” the “Neutral” wire (Ground)runs very very close to the L1 (hot) wire. Why would the current shoot throught feet of water and your body when it has a path that is usually no more than a 1/4 away on the circuit board???
I call BS on this MythBusters.. Its nothing more than an old wives tale. Have you EVER heard of anyone dying this way ?? Dont you think a few more people would have done it if it actually killed you either on purpose or accident?
Only in in TV land and I guess mythbusters is tv land

By: Jason

Jason — Wed, 09 Jun 2010 18:32:22 +0000

Stephen, if you washed yourself before bathing in the distilled water, you might be safe (not that I’m recommending that you try it.) The very sweat on your skin washing into your bath water would be enough to give the water enough conductivity to electrocute you. If you washed yourself beforehand and then bathed in distilled water, you might be safe for a short time. Just as the danger of electrocution in a large body of fresh water is low because the salinity from your sweat is diluted enough to reduce the conductivity of the water.

By: zena noble

zena noble — Fri, 30 Apr 2010 13:34:35 +0000

can you do more on quicksand?

By: sam

sam — Mon, 28 Dec 2009 20:29:43 +0000

oh yeah just fair warning make sure youre wearing properly insulated gloves goggles,safety equipment and someone ready to unplug a cord wich i recomend be plugged far enough away from the action. and try ,to stand back or hhve a safe stick (non conductive of course)to insert the power giving you some distance.from you and the water. you never know with electricity.

By: sam

sam — Mon, 28 Dec 2009 20:18:11 +0000

its sad to see that there are all these electronics major and all these electrical degrees flying around and everyone is so close and throw out ohms law and still cant get it right. its not the volts that kill you its not the amps that kill you and its not the resistance that kills you , its the combination of all three!!.Volts is the potential of force like having a bull dozer or having a ferrari parked in front or having a wide hose. you have the potential to do damage, speed, or flow..but if they just sit there then you have nothing. now amperage is energy put on motion like stepping on the gas pedal on the ,bulldoser or ferrari or opening the handle to let water flow through the hose.Resistance is what is stopping the action from happening.a rough rocky terrain with pot holes may slow down the movement or may be enough not to even let car or bulldozer move. flat tires may do the trick. a rock in the hose, a kink in the hose these can all be measured in resistance. . You need the potential like a car a hose or a tool to do the job(volts) you need the gas to be fed to the car,bulldoser, water to be turned, tool to be swung around(amperage) and you need low resistance for things to be able to flow like a smooth road or a clean hose with no kinks. or air space to swing a tool.(Resistance (or lack of) Ohms law is like a triangle. without each corner there is no triangle. as far as the fish are concerned ther is little or no load. try covering the bottom of the fish tankwith a ton of copper nails that way the fish will be
in direct path of the current flow .add some minerals in powdery form as to dissolve int the water. i cant guarrantee it but im sure it will get you closer of course it should be a small fish tank not a huge one.

By: Jacob

Jacob — Fri, 20 Nov 2009 20:49:59 +0000

Quick sand is very real. My father and I was walking on this scaly dirt because we seen this huge pile of turtles cooking in the sun. Well suddenly they disappeared. We freaked out and all of a sudden we went in. It wasn’t nessarily slow, but it wasn’t fast either. We got to about to our shoulders and stopped then we had a rough time getting out.