Farm Shock?

Where does the current go from a damaged underground wire?

Dear Mike,

As a boy of about 8 or 9 I was standing around while an electrician was trying to figure out why the pump on our water well on the farm wouldn’t work. I was standing in mud an inch or so deep with water puddles in cow tracks. I was wearing leather boots. I told my dad that my feet were getting shocked when I stepped in one area.

They found a bad wire buried directly, no conduit or anything. It was buried, as I recall, a foot or more deep. With the standing water and mud the earth wasn’t totally getting rid of the current. -James R.

Hey James,

You are 100% correct. While the earth is a great electrical “sink” for large currents from lightning strikes, it’s pretty poor for local electrical faults from things like grounding rods and buried wires. In fact, most ground rods measure around 25 to 100 ohms impedance.

Of course, that’s enough earth conductivity to electrocute a human or animal, but not enough to drain away any fault currents over a small area. So it spreads out the fault current path to feet or yards wide. In your case the 120-volts from the damaged underground wire could easily spread out several feet in muddy earth.

This is exactly why you should never walk anywhere near a downed power line since the fault currents can reach out a dozen yards or more. And if you spread your feet out while walking, the differential voltage can be enough to paralyze you and eventually kill you.

Read my in-depth article on safety around downed power lines HERE.