Quick Answer
Different livestock require different minimum voltages for effective containment. Cattle are easiest to contain (2,000–3,000V minimum), while goats and pigs need 4,000–5,000V. Horses need high voltage for initial training (4,000–5,000V) but maintain respect at lower levels. Always measure voltage at the far end of the fence run, not at the energizer.
Voltage Requirements by Animal
| Animal | Minimum Effective Voltage | Recommended Target | Reason |
|---|---|---|---|
| Beef cattle | 2,000V | 3,000–4,000V | Thin skin, well trained after first shock |
| Dairy cattle | 2,000V | 3,000–4,000V | Similar to beef; more contact with humans |
| Horses | 3,000V | 4,000–5,000V | Need strong initial impression; respect well after |
| Sheep (shorn) | 3,000V | 4,000–5,000V | Less wool insulation than unshorn |
| Sheep (woolly) | 4,000V | 5,000–7,000V | Wool insulates against shock |
| Goats | 4,000V | 5,000–7,000V | Persistent testers; higher conductivity needed |
| Pigs | 3,000V | 4,000–5,000V | Low body resistance; respond well to proper voltage |
| Poultry (in netting) | 2,000V | 3,000–4,000V | Small body; feathers reduce contact area |
| Predators (coyote) | 4,000V | 5,000–7,000V | Need strong deterrent to change approach behavior |
| Bears | 5,000V | 6,000–8,000V | Thick skin and fur require very high voltage |
Why Voltage Drops Along the Fence
Voltage at the energizer may be 7,000–8,000V (no-load output). By the time it reaches the far end of a 1-mile fence with moderate vegetation contact, it may be 4,000–5,000V. Add a second mile or heavier vegetation, and it drops further. This is why you must measure at the far end, not at the energizer. An energizer that tests at 7,000V at the terminal but only delivers 1,500V at the fence end has inadequate output, a grounding problem, or heavy vegetation drain — not three separate problems, just one cause driving a cascading result.
Voltage vs. Joules
Voltage alone doesn't tell the whole story. A 5,000V fence with 0.1 joule of energy delivers a sharp but weak shock — effective on horses, borderline on goats. A 4,000V fence with 2 joules delivers a stronger, more memorable shock even at lower voltage. For woolly sheep and persistent goats, joule rating matters as much as voltage — aim for 1–3 joules output for these species, not just high voltage numbers.
Seasonal Voltage Variation
Expect voltage to drop 500–1,500V in summer versus winter on the same fence. Wet vegetation grounds the fence more heavily in spring. Dry summer soil reduces ground system effectiveness. Test seasonally and adjust — some operations use a higher-powered energizer specifically for summer conditions and switch to backup mode in winter.
Our Recommendation
Use 4,000V as your minimum target measured at the far fence end for most livestock. For sheep with wool and goats, target 5,000–6,000V. Use a digital voltmeter (not a simple neon tester) and check monthly. If voltage consistently falls below target, add ground rods before assuming the energizer needs upgrading.