There's a trick of trade from the old days for testing the electric fence without using a tester and without grabbing the wire with your bare hand. What you'll need to get is a longer piece of green grass about 8 or so inches long. Squat down to a knee, pinch one end of the blade of grass between your thumb and index finger and lay the other end on the fence wire. You should feel a slight ping in the blade of grass. As you move the blade of grass inwards the ping will get stronger, so be wary of moving the blade of grass to close if you can already feel it. The green blade of grass will eat up about 90% of the shock.