Electric Fence

[Stoday]

I think this bloke was lying to save his bacon.

An electric fence on 12V could not kill a cat leaving it smoking. He'd connected up the 230V mains and could have killed a man let alone a child.

Should have been jailed.

Killer Pensioner

 

[ban-all-sheds]

He'd connected up the 230V mains

Why didn't it say that in the report? Particularly as it had been inspected by an electrician.

 

[Inky Pete]

It doesn't say that an electrician had inspected the set up, only that the court had heard from one.

The sparky was probably just asked his theoretical opinion of the set up the pensioner claimed he had.

There's no way 12V from a battery charger would fry a cat, one little belt and it'd be off. I reckon he probably did have it hooked up directly to the mains and made up the 12V bit after cooking the poor beast.

 

[ban-all-sheds]

True - apologies - no mention of an inspection.

But an expert witness could not assert that the guy had connected it to the LV supply without proof, and there's not even an opinion that "he must have done".

The opinion of the electrician was that 12V could kill a small animal or injure a child.

I think this bloke was lying to save his bacon.
.
.
.
Should have been jailed.

Thankfully we don't jail people because in the eyes of people not present at the trial, with no evidence of any behaviour meriting jail, and in contradiction of expert testimony, they think they were lying.

 

[sjwkmje]

It doesn't say that an electrician had inspected the set up, only that the court had heard from one.

The sparky was probably just asked his theoretical opinion of the set up the pensioner claimed he had.

There's no way 12V from a battery charger would fry a cat, one little belt and it'd be off. I reckon he probably did have it hooked up directly to the mains and made up the 12V bit after cooking the poor beast.

Young cat, it could have had an heart condition, it said 15A, we know chrage is equal to the current multipled by the exposure, Q = IT, so we could say that 15J would flow in 1 second. I know from my training that these low levels are used with children to return the heart back into normal rhythm (defibulation) or direct.

Current through the chest for a fraction of a second may induce ventricular fibrillation, so Q = IT = 15 * 0.5 = 7.5J. If not immediately treated by defibrillation, fibrillations are usually lethal because all the heart muscle cells move independently. Above 200 mA, muscle contractions are so strong that the heart muscles cannot move at all.

I think it is possible to kill a cat this way! Even possible to hurt a child. The voltage does not matter here its the current and time of exposure.

Defibulators go all the way down to 1J.

I might be wrong as I was taught all this stuff 4 years ago and you do not really have much use for it when working as a spark and not repairing defibs!

Some good info here http://www.physiocontrol.com/products/defibrillators/product-detail.aspx?id=552

We can also factor in the voltage:

0.5 * c * v^2 = 0.5 * j * v = 0.5 * 7.5 * 12 = 44.4J

Its theroretically possible. You would have a charge of 44.4J accross your chest more than enough for your heart to go into ventricular fibrillation.

Adam

 

[bernardgreen]

The news item referred to was

Last Updated: Thursday, 22 May, 2003, 08:02 GMT 09:02 UK

Your arguement has assumed a 15 amp current occurred but has not taken account of the voltage needed to create a 15 amp current through the un-known resistance of the victim's body.

"simple" defibs calculate the current and time for the required charge to be dispensed into the casualty's body. The voltage is turned on and rapidly adjusted to give the required current. Then switched off when the required current has flowed for the required time.

Later more intelligent defibs measure the resistance between the pads before applying the shock and then calculate the initial voltage and time and waveform to apply.

http://www.resus.org.uk/pages/faqDefib.htm

http://tinyurl.com/qnhl76

 

[Inky Pete]

I'll measure the resisitance from my cat's tongue to the pads on her paws later and report back.

I'd imagine it will be at least 10,000's of ohms if not significantly more - just now I am about 1/2 a megohm tongue to fingers.

So a 12V supply would only produce a tiny fraction of an amp of current.

 

[Spark123]

Anyone ever put a 9v battery terminals across their tongue before? I wouldn't recommend it - however to an animal that doesn't know any different the feeling could have caused it to panic, the stress from the panicing causing the death rather than the electric current.

I very much doubt that they managed to get the full 15A through the cat, probably only a few mA.
And remember to keep small children away from your 12v train set!

 

[Inky Pete]

One side of my tongue to the other = 9kOhms

Since cats tend to sniff at things before touching them I should probably meter out my cat from nose to paws.

If it'll let me.

 

[Spark123]

Make sure it's claws are away from your genitals before you press the test button.

 

[Inky Pete]

http://www.toysrus.co.uk/Toys-R-Us/...ts/Hornby-Midnight-Freight-Train-Set(0015150)

Suitable for ages 5+

 

[Spark123]

Nah - they'll have grown out of Thomas Tank by then

http://www.newmodellersshop.co.uk/thomas_the_tank_engine/r9071_thomas_the_tank_train_set.htm
Ages 3+

 

[sjwkmje]

The news item referred to was

Last Updated: Thursday, 22 May, 2003, 08:02 GMT 09:02 UK

Your arguement has assumed a 15 amp current occurred but has not taken account of the voltage needed to create a 15 amp current through the un-known resistance of the victim's body.

"simple" defibs calculate the current and time for the required charge to be dispensed into the casualty's body. The voltage is turned on and rapidly adjusted to give the required current. Then switched off when the required current has flowed for the required time.

Later more intelligent defibs measure the resistance between the pads before applying the shock and then calculate the initial voltage and time and waveform to apply.

http://www.resus.org.uk/pages/faqDefib.htm

http://tinyurl.com/qnhl76[/QUOTE]

I ignored resistance as that is delta R and is measured by inducing a small current and working out the voltage. Ohms law from there. Bi Phasic Defibs take the resistance into account. To work it out correctly I remember it been some calculus function. I was trained with the LP20 on that like I showed and a dummy called resus anny who had a large resistor in her chest, and when we did load tests we discharged the defib 15 times at 360J into a resistive load. We had a tester that would then log and record the results.

But even taking R into account its going to be infintatnley high so not going to introduce much change to the calcs I did.

I all ways remember we never really took resistance into account.

I think that they should have done an autopsy! This is all speculation and theroy but we do not know the actual cause of death.

Adam

 

[ColJack]

Anyone ever put a 9v battery terminals across their tongue before? I wouldn't recommend it - however to an animal that doesn't know any different the feeling could have caused it to panic, the stress from the panicing causing the death rather than the electric current.

I very much doubt that they managed to get the full 15A through the cat, probably only a few mA.
And remember to keep small children away from your 12v train set!

...with smoke still coming from its mouth...

sure.... it paniced and had a heart attack.... must have been the 20 a day habit it had that weakened it's heart..

 

[ban-all-sheds]

...with smoke still coming from its mouth...

[EDIT]

Truthfully, I am editing this without having done a refresh - dunno if anyone has pointed out yet another mistake in my reading of the reports - could have sworn it was the adult owner who found the cat, not the girl.



Not my day today....

[/EDIT]