how big of an area are you trying to fence? i have mine in a 2 1/2 acre lot right now and i have three foot wire mesh with a single electric wire about 10 inches off the ground. i'm using a 5 mile pulse fencer that i got at a local TSC store. i have found it's not as much the shock they get, as it is to get them to respect it. if they can jump over it, then it does no good.

You need a high-voltage/low-impedance fence energizer for goats & sheep. The old-fashioned 'weed-burner' types won't get the job done.
I've seen documents indicating that you need at least 7500 volts to effectively contain small ruminants.
2500 volts will pretty effectively contain cattle & horses, but you need a lot more jolt to keep small ruminants in.

Do you have adequate grounding? My energizer is grounded by a series of 6 eight-foot ground rods, each placed 10 ft apart, with the last one actually about 3 ft out into the farm pond.
In some instances, it may be necessary to have alternating hot-grounded-hot-grounded-hot wires in your fence setup to make sure that sheep/goats make good contact and receive the proper shock.

Here is a link that might be useful: Premier - goat fencing