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People who won't listen #149864 05/06/04 12:31 PM
Joined: Sep 2002
Posts: 1,497
C
C-H Offline OP
Member
About a month ago the weekly engineering news paper here in Sweden had a question what would happen if you put a live mains voltage cable in the bath. The question posed to the readers was: Will it kill you?

I wrote in to answer: It may.
(I'll leave out the rest here, but Mike Holt had a good explanation) Anyway, my answer got published. In it, I clearly warned the reader from putting it to the test.

A reader didn't believe me and decided to put the theory to the test. It turns out I was right in that the current will flow through your body. Fortunately for this guy, he escaped unharmed. Unfortunately, he went on to write a letter to the paper in which he tells that it is not dangerous to do this. After all, he survived... "The current in the water is only a few hundred milliamps" [Linked Image]

I'll admit he went about it in a scientfic manner, measuring the current and voltage, but I also think his experiment was a good attempt at a Darwin award.

[This message has been edited by C-H (edited 05-06-2004).]

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Re: People who won't listen #149865 05/07/04 04:42 AM
Joined: Jul 2002
Posts: 8,346
Trumpy Offline
Member
OK C-H,
Let's put this to the test (in Theory only).
Your body has an Electrical Resistance of 300 ohms, when it is dry!.
Immerse a person in water and you have a whole different story.
OK, it takes a current of 1mA to kill a person, when they are wet (immersed or not).
People have been killed with less than 20V in Damp Areas, namely, Bathrooms and the like.
Ask me, I turn out to these calls to investigate the darned things!. [Linked Image]

Re: People who won't listen #149866 05/08/04 05:51 AM
Joined: Jul 2002
Posts: 8,346
Trumpy Offline
Member
I'd like to ask a question of my fellow Moderator Bjarney.
Scott, would this situation set up a Voltage Gradient in the water in the bath?.
Providing that the Waste is laid in PVC,where is the path to Ground that provides the shock current?.
Even so, doesn't impure water have a lower impedance than the Human body, even when immersed in water?. [Linked Image]

Re: People who won't listen #149867 05/08/04 03:51 PM
Joined: Apr 2002
Posts: 2,527
B
Bjarney Offline
Moderator
My best guess would be that there are too many variables to say one way or another. Most of the published material on human shocks is based on C F Dalziel’s work in the middle of last century.

Water conductivity is most greatly affected by mineral content. This can be demonstrated to oneself with a bowl of water, a salt shaker and an ohmmeter.

The path of current and resultant voltage gradients at any given moment are predictable under very controlled conditions, but in real life, can change rapidly in an accident situation. For simplicity’s sake, consider two wires in an insulated container of water. The electric potential at any two points can change radically with moving the two energized conductor positions, and the points of contact to a human body part immersed in the water.

It is important to realize that current through a body part will significantly increase if the skin is wet. That is one reason why conductive objects in the vicinity of swimming pools, even through “non-electric,” are mandated to be bonded together to limit even very small potential differences between them.

Two miscellaneous online references are.. www.schneider-electric.com/en/pdf/ect114.pdf www.dep.state.pa.us/dep/deputate/minres/dms/website/electrical/Bob's%20electrical%20program.ppt

Re: People who won't listen #149868 05/14/04 08:15 AM
Joined: Aug 2002
Posts: 35
S
strangedog Offline
Member
The cord in a bathtub thing is like everying else. A small current won't kill you UNLESS. We all have been shocked at one point or another. Unless the path to ground crosses the heart we all can take a little bite. You could sit in the tub, with it's plastic drain pipe all day long, but the second you reach up to touch (the copper piped) faucet you will get the last shock you ever need.

At low current flow, the path through the body is what determine a lethal injury from a tingle. Just ask the guy who peed on the electric fence.


SD
It is best for a leader to be both feared and loved. But since this usually cannot be done, it is safer to be feared.

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