# Electrocution

Why do people die when they jump
into a pool that has a faulty
light in it? Or, why does a radio
(hair dryer,lamp, or other
electrical device) thrown, or
dropped, into a bathtub kill the
person in the tub? I know THAT it
does but don’t understand WHY it
David, here

For the same reason when you stick a knife in a toaster you get shocked.

Water conducts electricity.

Think of you and a toaster. You can stand next to it and not get electrocuted because air doesn’t conduct electricity. Put a knife in the toaster and now there is a direct link between the toaster and you. The knife conducts the electricity.

Apply this example to water. Toaster on land. You in water the air between you doesn’t conduct electricity. Throw the toaster in the water and now there is a direct link between you and the toaster – the water. Water conducts the electricity from the toaster to you.

That is a simple explination. There is more I’m sure someone else will elaborate on.

The electric company, in it’s wisdom, set us up with a system that alternates at 60 cycles per second (Hz), something that resonates too well with our neuromuscular system for our own good. I’ve seen a video of a man having a million Hz pass through his body without ill effect, but 60 Hz causes general muscle contractions, and is particularly noxious to the heart. It can induce asystole (no contraction), or ventricular fibrillation (disorganized contraction). In either case, immediate CPR and ACLS gives you a good chance, but if the pt goes untreated for 5 min or so of those rythyms it’s pretty much over,
Larry

Gee, thanks. I’m afraid to use my hot tub now.

lvick:

Well, that begs two questions:

(1) Why was this figure decided upon? Was it a chance number? Or is that number the most efficient way for electricity to go?

(2) Why not change it to a number that would enable my TV to fall into my bathtub and do nothing bnut mess my TV up? If it saves tons of lives, you figure someone would look into the feasibility of this.

Yer pal,
Satan

Just one point: Anything, including air, will conduct electricity if the voltage is high enough.

Actually, water does not conduct electricity. It is the impurities in water which conduct the electricity. A friend of mine owns a chemical research company and uses very pure water for various procedures. They measure the purity of the water by checking the conductivity of it. The greater the conductivity, the less pure it is.

“The problem with the world is that everyone is a few drinks behind.” - Humphrey Bogart

UncleBeer, you beat me to it. Though I think what you mean is that water doesn’t conduct electricity well. Given the appropriate voltage, I don’t think anything would not conduct electricity. In certain cases water, or its impurities, will conduct electricity when nothing else will.

Only humans commit inhuman acts.

Yep, that’s what I meant. You and Nickrz are correct. Everything will conduct electricity at the proper voltage/current. I believe this property is called the dielectric constant.

“The problem with the world is that everyone is a few drinks behind.” - Humphrey Bogart

Along these same lines, I understand that the electrical companants of a hot tub are sealed, but I always get nervous in one. Do people get electrocuted in hot tubs because of faulty wiring? The whole thing gives me the willies, and I plan on buying a hot tub soon… (party at my house!)

Some mornings it just doesn’t seem worth it to gnaw through the leather straps.
Zettecity

Cool, Zette! And if the wiring is faulty, it would double as a lobster cook!

planting seed of doubt further in her head HEH HEH HEH!

UncleBeer said:

I believe this property is called the dielectric constant.

The Resistance of a material or circuit is what determines how much current will flow for a given applied voltage. For AC circuits an equivalent - impedance - is used. It’s sometimes called AC resistance.
The dielectric constant refers to another property of matter. It’s used in the definition of capacitance and is commonly associated with insulators.
In an AC circuit you might make a case that it affects the current flow through the external circuit containing a capacitor in series, but I think Resistance or impedance are the terms you want.
There are several ways to die from contact with electricty.

1. Organ damage from heating and burning. This would result from a lighting strike or contact with a high voltage line.
2)Heart and breathing stops due to massive muscle contractions. Can be caused by contacting AC or DC with a high enough voltage to cause 6 Amps or more to flow through the body. Oddly enough, a reapplication of that much current can cause a stopped heart to re-start - thus the defibrillator used for that purpose.
2. Heart stops or fibrillates. This can happen with a very low current - .006 AC amps - if the frequency is right. As someone mentioned, 60 hz is just about the worst frequency that could have been chosen.
I suspect it was picked because of the number of windings that are convenient to put on an armature and the speeds at which it was convenient to spin it.
As far as hot tubs go, if properly installed, they are connected with a device (ground fault detector) that senses current flowing through the neutral leg and shuts off the power - hopefully before your heart stops.
In addition, switches such as the one that turns on the underwater lights are air operated so you are very isolated from any contact. Although I can’t quote any numbers, I think hot tubs are probably extremely safe.

Thank you for the clarification, Diver. I am a mechanical engineer by training. The most useful thing I know about electricity is, if you touch it, you’ll wish you hadn’t.

I just can’t always deal with things the existence of which, can only be proven mathematically. Give me a good old gear or piece of steel any day.

“The problem with the world is that everyone is a few drinks behind.” - Humphrey Bogart

UncleBeer said:
I just can’t always deal with things the existence of which, can only be proven mathematically

All I can say is it me longer to do the homework for my mechanical engineering dynamics class than any electrical course I took.
Electronics for me, Mechanics for you - different strokes for different folks I guess.

Satan:

1. I have no idea about the origins of this system, my WAG would be that it was in place before they figured out it was dangerous.
2. You’d have to change all the electrical devices in the country and no small portion of the power grid. Cheaper to toast a few mortals,
Larry

I run electrical discharge machinery (EDM) for a living. These machines use (what else?) a high-frequency discharge of electricity to very accurately cut (erode) just about any electrically conductive material.

These days, the whole process takes place under water - deionized water. The water (dielectric) must be free from any solid contaminants or free ions that would allow the plasma channel (discharge) to occur prematurely. We filter the water down to 2 microns at all times and lower the conductivity to 2 microsiemens when cutting tungsten carbide or polycrystalline diamond compacts.

So, in effect, my livelihood depends the fact that (extremely pure) water does conduct electricity efficiently under the right circumstances.