FACTS about bears and fences: introduction
Bear Height and Fence Height
Adult bears (both grizzlies and black bears) generally range in height from 3 to 4 feet when they are on all fours. And since standing bears, even circus dancing bears, cannot hop over obstacles very well, this implies that no electric bear fence needs to be over 3 feet high. Indeed, these facts suggests that any electric bear fence over 3 feet high has this added height not so much to deal with bears as to reassure its owner.
How Bears Contact Bear Fences
You would never guess how your typical bear contacts an electric fence—unless you recall that a bear leads with its head and has powerful jaws. That’s right, it bites the bear fence. That creates a really good electrical contact between the bear fence and the bear. So if the bear does this, under most circumstances far less than the recommended 4,000 volts are needed to give it a good shock
Because volts are the electrical equivalent of pressure, volts determine shocking ability. We recommend that you have something like 4,000 volts on the line even if they are not usually needed, in case the bear decides to touch the fence without biting it, in which case the 4,000 volts may be needed. If you are camping out, so long as there is no food nearby, you probably don’t need much power (measured in joules) to send the bear away. That’s because bears don’t understand electricity; most of them don’t really want to be near people; and they tend to shy away from averse things that are unfamiliar. So a little charger like the Field Guardian D Cell (Model FGBD35) that operates for up to 4 weeks off of four D cells (flashlight batteries), yields up to 4,000 volts, and produces a small maximum jolt of .35 joules can do the job.