we've got 3 pastures separated (and surrounded) by 3 strands of 17 ga wire. Of course, we just have miniature horses ... but I can tell you that they definitely have a lot of respect for it! We've had one instance in the past (just last month) where a yearling got to close, panicked and pushed the top strand out to get away .... took me 2 minutes to replace the one broken stand-off. The wire is significantly cheaper than the tape. If a horse bulled through, the t-post stand-offs would break and allow the wire to push out far enough to cause no damage.
The horses learn respect immediately and, as was previously noted, don't test. I moved some pasture and it took a long time before they'd venture past the prevkious line .... I finally had to take my old gelding and lead him across the old line to show them it was safe. I also had a corner where one of the neighbor punks, I mean kids, ran into the t-post with an atv ... and bent it to the ground ... so the wires were all laying on the ground. The horses never strayed throug that spot even though it was several weeks before I noticed.
When I let the older mare in with the stallion, I have to visibly and pointedly move the gate (accordian) wire aside ... and then she finally stampedes through as fast as she can ... she's that afraid of the wire. I have a real problem getting her back to the barn if I go out to late at night ... since she can't see the wire, she won't believe the gate isn't still up ...
As was mentoined, the ground is critical .... I finally extended mine to four 6 ft ground rods. Now I need to remember that I have leather soles on when I step over the fence (I said they were minis, didn't I?)
pete