"...Since electricity will only travel through a closed circuit, the fence wire, energizer and ground rod are three parts of a circuit waitiThng to be closed; when a bear touches the wire, it closes the circuit, and electrical current flows through the bear. Consequently, the bear will feel a shock, really rather a sharp jolt of electricity, which strongly discourages him from touching the fence again. Most bears I've witnessed getting shocked cannot put enough distance between themselves and the fence fast enough. The strength of the shock depends on the energizer's voltage and amperage: Voltage, measured in volts (V) or kilovolts (kV), is the force or pressure with which a current flows through the circuit. The higher the voltage, the farther the current can travel through the wire before resistance slows it down; higher voltage also causes a stronger "zap" from the shock. Amperage (amps) measures the magnitude, or strength, of the current flowing through the wire. The higher the amperage, the greater the sensation the current will cause when it enters a body..."

From:http://www.absc.usgs.gov/research/brown_bears/safety/electric_fencing.htm



"HOW MUCH VOLTAGE?

You can't have to much, only too little. Bears have heavy fur, very thick skin, a high tolerance for pain and heavy foot pads that minimize grounding. This is one reason that an alternating ground wire configuration is recommended. Because they have big thick fur coats and insulating layers of fat, the latest recommendations suggest a minimum of 6,000 volts to effectively shock a black bear."

From: http://www.bearaware.bc.ca/electric-fencing.htm



Notes:

- Any factory-made and bear-proof (up to 16 000 Volts!) Chargers/Energizers/Controllers are VERY dangerous, especially when you or your neighbor accidentally (like the deer below) get tangled in the wires. Such an incident may be fatal.

- Physiological effect of electric current 100-300 mA (1 second contact) is ventricular fibrillation and may be fatal if continued!

- "If you have just played a couple of sets of tennis, are sweaty and barefoot, then your resistance to ground might be as low as 1000 ohms."

- As an electric fence builder you have to remember about your responsibility for any accidents related to your fence.



There are tree types of Electric Fence Chargers/Energizers/Controllers: AC powered, DC powered and Solar powered.



