Short answer: Usually the fence has not changed; the ground has. Alberta Agriculture's electric fence factsheet (Agdex 684-17) says "The soil is a poor electricity conductor compared to wire, especially if the ground is frozen or covered with snow." The Alberta and Manitoba guides below point to the same three checks: read the voltage at the far end of the fence, test the ground system, and, where animals only touch a hot wire, add a grounded wire so the shock does not have to travel through frozen soil.
Why does an electric fence get weaker in winter?
Manitoba Agriculture's electric fencing guide describes the circuit: "When an animal touches the hot wire, current flows through the animal to the ground and back to the energizer via ground rods". In winter that return path runs through frozen soil and snow. Alberta's factsheet puts it this way for an animal that touches only a charged wire: "The intensity of the shock received by the animal is considerably less than if contact is made with a charged wire and a ground wire."
Steve Kenyon, who bale-grazes at Busby, Alberta, made the same point in Canadian Cattlemen (March 2011): "Electric fence is not as effective in the winter due to the insulation of the snow and frozen ground."
Will an electric fence work in snow?
It can, but a single hot wire over frozen ground delivers less than it did in summer, so the targets go up. Manitoba's guide lists "Summer: ≥ 2,000 volts (dry ground, thinner hair coats)" and "Winter: ≥ 4,000 volts (thicker hair, snow/ice reduce grounding)", and says to "Aim for ≥2,000 V summer / ≥4,000 V winter at the far end of the fence."
Snow depth matters too. In the Alberta factsheet's winter hay-yard design, the first charged wire is set high enough that more than 0.6 m of snow has to build up before it touches the wire, and the factsheet adds that if deep drifting snow makes the fence hard to run, "a snow fence may need to be installed on the upwind side of the electric fence."
How do you ground an electric fence in winter?
The answer in both Alberta sources is a grounded wire on the fence itself, so the animal completes the circuit between two wires instead of through the frozen ground. The Alberta factsheet says "This is why a system that uses alternately charged and grounded wires is recommended", and its winter design reads: "The wires should be alternately grounded and charged, beginning with a grounded bottom wire." The grounded wires run back to the ground rods; the factsheet says to "Attach the grounded wires to the ground rods with a ground rod clamp".
Kenyon describes a short two-wire training fence by the winter water: "The top wire is hot and the bottom wire is grounded. For it to shock the animal, they have to touch both wires."
For electric netting, our guide Electric Netting for Chickens, Sheep and Goats: Choosing, Powering and Grounding a Net covers positive/negative nets, which work on the same principle.
How many ground rods does an electric fence need?
Manitoba's guide lists a "Minimum of 3 ground rods, each 6–8 ft (1.8–2.4 m) long", says to "Place rods ≥ 2 m from the energizer and ≥ 3 m apart", and to "Use galvanized rods, clamps, and wire for connections (resists corrosion)." It also says: "Do not use copper to connect ground rods to the energizer—it corrodes."
The Alberta hay-yard design used "two 1.5 m ground rods that are completely driven into the ground", about 2 m apart. Rod length and count vary by energizer, so follow your energizer's manual where it asks for more.
How do you test an electric fence in winter?
Manitoba's guide gives the ground test: "“Ground out” the fence (e.g., press a metal bar against a hot wire) and measure the ground system with a voltmeter." Then: "If the ground rod reading is > 200 V, add more ground rods." and "A well-grounded system should read near 0 V at the ground rods."
Its final tip is to "Record your baseline voltage readings after installation", so a winter reading has something to be compared with.
Energizers and power in cold weather
Alberta's factsheet, written for a winter hay-yard fence, recommends a plug-in energizer: "Use a plug-in energizer because the battery-operated ones do not have enough energy to power the fence during extremely cold weather." It adds that an extension cord, if one is needed, should be heavy gauge. For solar units, Manitoba's guide says "Fully charge batteries before winter storage; check panels and leads." It also says to "Install a lightning diverter/arrestor to protect the fencer."
For sizing an energizer, see our guide Electric Fence Energizer Sizing: How Many Joules Do You Need?
Winter grazing tips from an Alberta bale grazer
Kenyon's Canadian Cattlemen article lists five winter rules for bale and swath grazing. In short: train the cattle to the fence in the fall ("I like to see over 10 KV in my fence in the fall."), build the two-wire fence by the water, set the next cross fence up before you open the current one, move fences in daylight, and keep cross fences far enough from the next bales that cattle are not tempted to reach under. Manitoba's guide has a similar winter option: "Use electrified corrals during feeding to reinforce respect."
Grounding and testing parts we list
Rod length, count and spacing should follow your energizer's manual and the guides above.
- Ground rods: Patriot 5' ground rod kit (3 rods, 3 clamps, 50' steel wire) · Speedrite ground rod, 6' x 1/2" galvanized (10 pack) · Corral t-shaped ground rod 1m · Speedrite t handle ground rod 30"
- Clamps and connection cable: Patriot Ground Rod Clamp · Speedrite heavy duty ground clamp (10 pack) · Corral fence earth connection cable 3m
- Voltmeters and fault finders: Patriot digital voltmeter · Speedrite digital voltmeter · Speedrite digital fault finder · Speedrite remote control / fault finder · Corral fence tester up to 10,000V · Patriot six light fence tester
- Underground cable for gateways: Corral premium underground cable 50m · Patriot underground cable - 50' roll · Speedrite premium underground cable 12 1/2ga x 165'
- Lightning protection: Corral lightning arrestor · Patriot lightning arrestor · Speedrite lightning diverter
- Positive/negative netting: Patriot positive/negative netting 50' · Patriot positive/negative netting 164'
- Energizers: Fence energizers and chargers
Related guides
- Electric Fence Energizer Sizing: How Many Joules Do You Need?
- Electric Fence Supplies Checklist: Ground Rods, Insulators, Gates and Testers
- Electric Netting for Chickens, Sheep and Goats: Choosing, Powering and Grounding a Net
Sources
- Alberta Agriculture, Agdex 684-17, "Using Electric Fences to Protect Stored Hay from Elk and Deer" (R. C. Acorn, 1993): https://www1.agriculture.alberta.ca/$department/deptdocs.nsf/all/agdex611/$file/684-17.pdf
- Manitoba Agriculture, "Electric Fencing for Livestock: A Practical, Professional Guide": https://gov.mb.ca/agriculture/livestock/beef/everything-you-need-to-know-about-electric-fencing.html
- Steve Kenyon, "Five Winter Fencing Rules", Canadian Cattlemen, March 14, 2011: https://www.canadiancattlemen.ca/features/fivewinter-fencing-rules/