Volts vs. Joules
Does an animal receive more of a jolt per volt or per joule? This is hard to test because there are few volunteers, let alone a way to accurately rate the shock. Nevertheless, there are key differences between volts and joules.
The following is a breakdown of volts versus joules:
There needs to be enough amperes sent to the fence to maintain 3000 volts on the fence. The voltage is what gets the electric through the skin or hide to the nerves. If there is very little load on the fence, the conductor (wire) can be very small like the stainless steel wires in twine because very little amperage is needed. A low power charger (even 1/10th joule) that maintains this voltage will do a good job of control. We do not recommend long pulse weed burners; they often start fires and melt twine. The 7000-volt range is good to maintain on the fence. If it is much higher there are more problems with the electric arcing across wet surfaces like insulators or insultube. There should be output control on the chargers to take the very high voltage spike out of the pulse.
When there are underground cables at gates (or from the charger) and heavy conductive growth on the fence, very high power chargers and 12.5 gauge wire is logical. I would recommend aluminum clad high-tensile steel for very long lines of single wire going to a heavy load area. Most of the power of a high power charger goes to the shorts (and inductance and capacitance load) on the fence, not the animal. When I mistakenly touched my fence that was hooked to a 21 joule charger I knew I never wanted that experience again. I got a black mark on my hand.
I do not trust the method many companies use to determine joule ratings for their line of chargers give a fair comparison with other chargers. There are too many variables involved and too many ways to calculate the joule. Even though our 12-joule unit is rated at 20 stored joules, what matters is that the 12 joule is what gets through the output transformer and onto the fence. Even the voltage at various resistance levels across the terminal (try 25 ohm or less on the bigger units) can mislead because that does not take into account the on time of the pulse. The size and voltage of capacitors which dump into the output transformer give a fairly good idea of the stored power, but the power will still have differing efficiencies getting to and through the output transformer.
Because Kencove sells chargers made by New Zealand, Germany and USA companies, we tried to develop a method to easily compare output power of chargers. We found for every 1.5 joule rating of most our chargers the filament of a 100 watt light bulb will just barely glow in a dark room. We normally hook them in series, but in the 18 and 28 joule we use several strings of lights. Our 6 joule charger should dimly light 4 bulbs and the 12 joule unit 8 lights. A few years ago I planned to sell a charger the factory rated at 10+ joules. When tested, we felt it was far overrated. I feel the better a charger does in this test, it will do better at killing the green growth touching the fence.
Although I used one 16 gauge high-tensile wire on fiberglass rod posts (5/8"x 5' ends and 3/8"x 4' mixed with 5/8" line posts) for our seasonal dairy operation, I see a place for the 6 wire 12.5 gauge H-T fence with 25' post spacing. Have the electric do the training for the actual control, but have enough wires the animals don't think they can get through. They are not as tempted to test the electric. The electric can be off much of the time. There is a lot of physical strength and long life in the fence, but it does not have to be super tight so dips, ends and corners are not as likely to pull. When wire is between 1 and 2 cents per foot per strand it is affordable for those wanting more peace of mind on their perimeter fence.