Voltage dissipates differently in animals and humans?

[Alan G]

In an accident at the weekend in my city, a dog was killed, electrocuted by a street light.

Monday article
http://www.thecourier.co.uk/output/2008/02/25/newsstory10981494t0.asp

Tuesday article http://www.thecourier.co.uk/output/2008/02/26/newsstory10986115t0.asp

There were concerns that as this killed a 65pound dog it could have killed a child. In Tuesdays article this was dismissed with the reasoning:

the Scottish Hydro Electric representative claimed that, because voltage dissipates differently in animals compared to human beings, he was confident the surge would not have killed a human being


Is this true or is it spin?

[Kotatsu]

Which humans among us are not animals? Is there an easy way to tell animal-humans and non-animal-humans apart for a beginner?

[shadron]

In an accident at the weekend in my city, a dog was killed, electrocuted by a street light.

There were concerns that as this killed a 65pound dog it could have killed a child. In Tuesdays article this was dismissed with the reasoning:

the Scottish Hydro Electric representative claimed that, because voltage dissipates differently in animals compared to human beings, he was confident the surge would not have killed a human being

Is this true or is it spin?

If it killed a 65 lb dog, it very well could have killed a human, child or not. The "voltage dissipation" is just a canard; voltage is dissipated by driving a current through a resistance, and one flesh is pretty much as good a resistor as another. All you need is 5 milliamps in the right place (across the heart), that's enough to cause fibrillation to set in, and pretty much any flesh and blood can be a goner.

[Alan G]

Thanks, that was my immediate instinct - just wanted confirmation.

[Mr. Scott]

the Scottish Hydro Electric representative claimed that, because voltage dissipates differently in animals compared to human beings, he was confident the surge would not have killed a human being

I would say a dissipation pattern in a person wearing shoes touching a street light with a hand would be very different from that of a dog touching a street light with a wet nose with four damp paws on the ground. That's probably what he meant, though he expressed it oddly.

[JWideman]

Statements like that make me want to say "Really? Hold this wire."

[Arkan_Wolfshade]

Just skimming the article I didn't see where contact was made. If it was made on the muzzle, then the current would pretty much have to travel through the chest cavity to the grounding point. Whereas, if you touched it w/ your hand, it would run down the side of your body.

Having worked w/ EE's for a number of years I learned the importance of playing "pocket pool" when fiddling w/ a breaker box. If you hand is in your pocket, then it can't be a ground point and a short won't travel across your chest to the ground point.

Side note, also, when throwing a the main breaker, do so w/ your left hand so you face isn't in front of the box.

[MattusMaximus]

If it killed a 65 lb dog, it very well could have killed a human, child or not. The "voltage dissipation" is just a canard; voltage is dissipated by driving a current through a resistance, and one flesh is pretty much as good a resistor as another. All you need is 5 milliamps in the right place (across the heart), that's enough to cause fibrillation to set in, and pretty much any flesh and blood can be a goner.


Actually, there are some mistakes here that need to be addressed.

First of all, assuming we're talking about alternating current (AC), 5 milli-Amps is not enough current passing through the heart to cause fibrillation (heart attack). I commonly shock myself with this much current in my physics classes all the time in demonstrations, and I have yet to suffer any ill effects to my heart. In order to get fibrillation, you need on the order of 60-70 milli-Amps of current passing through the heart muscle. 5 milli-Amps is usually only enough to cause pain & discomfort.

Second, all flesh is not the same in terms of electrical resistance. Again, I perform demonstrations in my classes that clearly show the difference between being connected to a voltage source when the skin is dry (high resistance, low current) versus wet (low resistance, high current). This is why you're told never to mess with electrical equipment when you're in the shower or bathtub. Depending upon the circumstances, the difference in resistance (and therefore current) can be as much as 10 or 20x.

Third, there is a physiological point to be made. Dogs walk on all fours, while humans do not. This is important because when a current passes through a dog's body, since the front legs are on the ground, a large amount of this current will naturally pass through the dog's heart. Whereas with a human the legs come nowhere close to the heart, so the amount of current passing through a human heart is naturally less than for the dog. A similar phenomenon is observed with cattle dying during lightning storms for this same reason.

[~enigma~]

I would say a dissipation pattern in a person wearing shoes touching a street light with a hand would be very different from that of a dog touching a street light with a wet nose with four damp paws on the ground. That's probably what he meant, though he expressed it oddly.
I agree with this. He probably meant that chances are with an animal the current almost invariably will cross the heart due to an animal walking on all fours. A Human OTOH walks on two feet so there is a greater chance of the current NOT crossing the chest cavity.