Well, Bedstor, I'm a semi-electrical person! Yes, ultimately it's the amperage (current) that does the dirty work. Specifically it's the current density within the sensitive electrical conducting system of the heart.

But whatever your impedance to ground might be just before touching the fence -- depending on everything from the moisture content of your skin to the type of footwear you are wearing -- the current will be proportional to the voltage. So 600 volts is riskier than 300 volts no matter what the circumstances.

I would worry about humans touching fences designed to shock cattle or other furry and thick-hided animals. A safe deterrent for a large animal might easily be lethal to a person.

I don't think zoos use electrical fences because walls and moats are so effective by themselves (SF zoo tigers notwithstanding). And what if the power goes down? (à la T. Rex in Jurassic Park...)

quote:

Originally posted by Leppi:
Valor D, as far as I see from the news, the zoo has not yet reopened, and the ealiest re-opening day as of now is january 3rd.

Yes, I read that, too. They must have had second thoughts once the Zoo regulators got involved.

quote:

Two questions I wondered about as I read the articles.
# 1, the hieght of the wall was lower then recommended. How high was the recommended height, and how many other zoo's are also below the recommended height.Also, it was lower then recommended height, but was it also lower then minimum height?

According to the latest article I posted: "It has become increasingly clear that the tiger climbed over the wall of its enclosure, which at just under 12 1/2 high was about 4 feet below the recommended minimum for U.S. zoos."

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#2. I read that the parents of the boy killed found out about it by way of the news, and not by way of zoo officials/police. Was this purposeful, or an accidental slip?

I hadn't heard this. But, with the speed of the Live Action News Teams these days, I really don't doubt that.

quote:

Originally posted by Professor:

I would worry about humans touching fences designed to shock cattle or other furry and thick-hided animals. A safe deterrent for a large animal might easily be lethal to a person.

Both sheep and cattle here are kept back by electric fences. When the poodle in this house touched one, he jumped at the shock and initially acted as though the sheep had caused it, eyeing them with great suspicion, before working out the answer ! They work because of the unfamiliarity, the consequent alarm,to the animal.The animal is wary as a result. Quite a small current is enough because the animal touches the wire with a thinly protected area of the body e.g. nose or face.Problem is that an animal is never going to be physically stopped by such a fence.There aren't many gently grazing tigers who will learn to back off when eating too close. The system depends on acquired behaviour

s

quote:

Originally posted by Professor:
I don't think zoos use electrical fences...And what if the power goes down?

Oh, but they do use them, extensively. The first time I touched one was in the elephant exhibit. I reached over and touched this wire running atop some gunite rocks and I asked my foreman what it was. He said "don't touch that, it's elecrified perimeter wire." I said "I just touched it and nothing happened." He said, "Touch it again and leave your finger there a few seconds." Sure enough, after a second or two, ZAP! I learned then that these wires are not continuously charged but the current is sent through in pulses, whose rates can be controlled at the wire's terminus. This is a metal box usually painted red and hidden from public view, and may have a red light on them that illuminates with each pulse. Look for them next time you visit a zoo.

Power out? Batteries, UPS, generators...

quote:

I would worry about humans touching fences designed to shock cattle or other furry and thick-hided animals. A safe deterrent for a large animal might easily be lethal to a person.

Perhaps they could arrange it in a 2 wire "V" with the inner wire at a High voltage and the Outer set at a lower Voltage each set at levels to say "Don't touch me" Engineering wise it'd would be easy to Make
And Bar the suicidal fool ignoring it The Notice reads Note the Wire at the Top It is Set to kill

And It can have a fast alarm circuit on It to alert Security

Kendor mentions "The Box" as I did earlier

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on top of metal posts 18 inches high...and a clicking Metal box..and I touched it!

It is set to pulse Capacitor discharge I Imagine? Similar to a Household Circuit of either 50 to 60 pulses

Measured in Joules on this site (Unknown what Amp Rating need translation ) they go from 0.25 to 36 joules discharge ratings
with this seller.

Another UK site Here does say on 1 unit that 1 Joule is good for keeping Animals and People apart. But Never ever think It's safe That's your first and Last warning OK?
Here is a pic of a setup barring a gateway against horses as you can see its extremely deceptive if you have little or no experience of the Countryside

Just found out Amps do not convert in Wikipedia They are unique. So educated guesses are welcome as to roughly what the ratings are .Who knows ?Another Electric Fence site will have the ratings in Amps?
Edit
A 12/24 volt system such as this Is rated @ 30 Amps ...Where that fits in the Pecking order I have no Idea

Though I do know that It can be lethal 30 Amps is the Same rating as running an electric Cooker Circuit in the UK!!

A rating of 12 volts at 30 amps is equal to 360 watts. So at a voltage designed to shock an animal without being lethal to a human, or animal would probably be in a range of at at least 6000 - 12000 volts. At 6000 volts the current available at the wires would only be about 60milliamps, lethal current for a human is roughly in the 200-250milliamp range, depending on the current path through the body, etc. Enough to cause one to let go before the next pulse of high voltage. A lethal current of a fatal magnitude produced by a discharging capacitor, generally would require an extremely large capacitor. I can't imagine an electric fence delivering lethal magnitude current being necessary anywhere. Unlimited voltages can deliver painful shock without ever being anywhere near lethal current values. IMHO. Of course, if one is climbing a fence at the time it could cause one to fall back down.

I was assuming continuous voltage. If it's a series of brief pulses, then there's much less risk.

Peripheral nerve stimulators delivering hundreds of volts, at pulse widths of a few microseconds, are routinely used in medical applications without harm to the patient (though it's an unpleasant sensation), since the current generally doesn't traverse the heart. Arm-to-arm or arm-to-foot current paths might not be so safe.

Have there been reported human fatalities from electric fences installed in animal enclosures?

I guess I didn't think zoos used electric fences because I never saw them. And I've been to the San Diego Zoo many times. I'll have to look harder next time!

quote:

Originally posted by Kendor:

quote:

Originally posted by DorianGreyed:
So, Kendor, are you saying that if someone climbs (or jumps) that fence, and gets into the cats' enclosure, it is the zoo's fault, not the idiot who gets mauled?

Yes, that's what I'm saying. There should be absolutely no way any idiot could get into a wild animal's enclosure, or for any animal to escape same.

Among other safety precautions at Cincy, they use shear space and electrified perimeter fencing between enclosures and public fencing to keep the animals and patrons separate. I know this first hand, as I have been zapped by it on more than one occasion. (I was aslo bitten on the elbow by an Alpaca while repairing its water trough, but that's another story).

Kendor, don't you think that stupid people will just be stupid, and it's a bit much to expect to plan for every act of stupidity a person might do?

I, Stupid person # 1, wants to visit the tigers, so I bring my grappling hook, and I use it to get over the moat....

I, stupid person # 2, want to pet see the fluffy tiger do it's roar thingy.... Lets see how many things I can throw at it before it starts that oh so adorable roar....

Part of life, is that unfortunately there are many stupid people. But to try to prevent any stupid act a stupid person might do, isn't that a bit much?

I'm pretty sure, that if you let a stupid person with a high IQ run free in any zoo, none of the exhibits are safe enough.

You know I have been a great admirer of these beautifule tigers, I really have mixed emotions about them being in captivity. I know they are an endangered species, so it just breaks my heart to see them killed. So, my reaction is....the zoo was not suitable for this wonderful animal, I really think that a wildlife habitat is the only way to go. It's not the animals fault that they are wild, and should be free. I think Bedstor's link showing how they are supposed to be captivated if they must is the ideal solution. Why would you cage an animal, and expect them not to want to roam and hunt. It's only natural. I have been to the Cincy zoo, I've seen the leopards in a surroundings of about a radius of 10 feet, and I think it's wrong. The tigers have a bigger yard with fencing that's wired above it, but if you can't accomodate all animals properly, then don't keep them. Man, how sad! It's a down right shame for both the animal and person killed.