Inside my shop I have my fifteen miles electric fence controller plugged in. From the controller I was using a three strand 12 awg wire that ran along my metal building about 25ft to the electric fence wire. Electric fence controllers click; so I didn't notice electricity was bleeding through the wire and arcing along the building. I'm currently only using it for about an acre and the shock around the yard was always good. The other night I happened to be in the dark and notice some arcing. I've been testing many theories until today. I used an electric fence tester and its reading about 1000 volts through the insulation anywhere on the line.

Why is this happening? This wire is good enough for a building with power tools, but a small amp fence controller can leak through its insulation. At the ground and fence knobs in the picture below; a reading will show 7000 volts. My three strand 12 awg wire allows for 600 volts. I see that is probably my first mistake.

Please help me improve this installation.

Electric Fence Controller

  • Are you not insulators on the building? There is fence wire made to go underground that should be good enough. Most house type insulator wire will bleed/short at those high voltages.
    – crip659
    Aug 30 '21 at 0:12
  • @crip659 - I've seen those. That should work. I'll look into those now. Thank you.
    – Ms. Prada
    Aug 30 '21 at 0:51
  • Found Underground Cable, 50 Feet, 12-1/2 Gauge, Rated to 20,000 Volts, tractorsupply.com/tsc/product/…
    – Ms. Prada
    Aug 30 '21 at 0:54
  • Gauge not that important, anything from 17 to 12 1/2 single will do. Preventing it from touching anything that goes to ground is very important. Fence wire insulators or underground fence wire are needed where ever wire can short to ground, steel/wood buildings, fence posts, other wires.
    – crip659
    Aug 30 '21 at 11:20

Electric fences are high voltage (kilovolts), controlled current and pulsed time.

Building wire is typically 600V rated insulation.

You need to treat electric fence feed wiring like electric fencing, with the appropriate separation between wires and insulated standoffs, or use appropriately high-voltage insulated wires if you are not going to do that.

The gauge of the feed wire is not a problem - the unsuitable insulation and lack of space to provide insulation via distance (air gap) is. You could use the same wires, removed from their cable jacket and placed on electric fence insulators well-separated from each other. You will need to be careful about anywhere that the wire passes through a building, and perhaps get some decent ceramic insulators for that purpose.

If you are losing 6000V between the charger (7kV) and the fence (1kV) it's pretty clear that your feed wire is not helping your fence to work correctly.

  • I'm not losing volts at the bare wire along the fence. Its just bleeding out 1000 volts through the jacketed insulated wire. I was thinking of just putting the wire in a small pvc pipe to avoid grounding along the building.
    – Ms. Prada
    Aug 30 '21 at 0:48
  • 1
    The wires will be shorting to each other inside the pipe if you do that, unless they are all carrying "hot" and ground is run separately. 7000 volts applied, 1200V of insulation if you take each wire having 600V to add up to 1200V if they are touching each other. If you use two separate pipes for the two separate wires, it might work. Use PVC conduit by preference over PVC pipe - it is sunlight resistant, and PVC pipe is not.
    – Ecnerwal
    Aug 30 '21 at 0:54
  • I found an Underground Cable, 50 Feet, 12-1/2 Gauge, Rated to 20,000 Volts
    – Ms. Prada
    Aug 30 '21 at 0:56
  • Well, that should work.
    – Ecnerwal
    Aug 30 '21 at 0:57
  • The thing to keep in mind, which I learned relatively recently, is that the voltage determines the insulation while the current determines the wire size (AWG). That's why high voltage transmission wires are (generally) high up on towers and spread far apart - they get to use lots of air as insulation but the wires themselves don't have to be very thick. Aug 30 '21 at 2:05

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.