Re: How many volts are in a joule?

While there is a technical relationship between the volt and the Joule, I 
suspect neither you nor your cattle are that interested.

What does matter is that you don't concern yourself about the voltage of 
your fence: the shock value does not come from that.

The ENERGY delivered by the shock however is critical.

The reason why we are only interested in the delivered energy is that that 
is what makes an electric shock undetectable perceptible, annoying, painful 
agonising or lethal.

Common experience of removing a sweatshirt and hearing and seeing the 
sparks fly should convince you that the size of the sparks ( and it takes 
25,000 volts to make a spark jump 1 inch in air), is independant of the 
capacity to hurt. 

Then again, walk across a nylon carpet in winter and touch a piece of 
grounded metal. That certainly starts to tickle ! yet that is probably 
again only 25,000 volts. But for some reason it hurts more. What is 
happening is that energy is being stored on your body and that energy is 
discharged through the metal. More energy more hurt

What matters is the current that flows and the voltage it takes to make it 
flow. The product of those two things
current x voltage gives the power that has been delivered, and dividing it 
by the time it flows gives the ENERGY in Joules which has been delivered.

So 1 amp flowing for 1 second being driven by 1 volt is 1 joule of energy.
1 amp for 0.5 second driven by one volt is 1/2 joule.
2 amps for 0.5 second driven by one volt is 1 Joule again !

If your body presents a low enough resistance at ANY voltage, for enough 
current to flow, then it may well give you a fatal shock. Which is why it 
is possible to be killed by a hairdryer in a bathroom on onky 110V, a wet 
body has much lower resistance than a dry one.

Which brings us to the cattle fencer. The manufacturers design it so that 
there is a very high voltage present between the fence and the ground, to 
make it jump to the skin of your beasts, but the fencer is VERY carefully 
designed to limit the ENERGY delivered. So if a beast urinates on it, she 
will receive the same shock as if she brushed against it with her rump and 
won't be injured.

I am not a vet, so I cannot comment on how you should set your fencer, only 
perhaps that you should experiment by presenting a tempting target 
surrounded by a test fence, when the animals won't cross the fence you have 
it set right and at a minimal value. 

Hope this helps.

Steve