Household Electrical Safety WARNING

[KXCam22]

A warning. This situation is extremely rare but has the potential to happen at any ones house. I just came in from troubleshooting a neighbors house. He was getting an electrical shock from touching his chain link fence and his outside hose faucet. I could measure 60VAC from the gate post to my multi-meter probe unscientifically stuck in the dirt. WTF. I measured his hose faucet at 51VAC to the dirt. Again WTF. I suspected a bad house ground but the ground wire to the copper piping was intact and the hose faucet was actually grounded. Double WTF. That indicated that the dirt itself was at 51VAC, caused by stray voltage in the ground. Measuring grounded faucet to chain link gate got me 110VAC. Yikes!!!. We searched for sources of AC power (like old xmas lites) to the fence but found nothing. The voltage dropped as we worked down the fence away from the gate. 50' away it was about 20VAC. I was stumped and about to call the utility company. I quized the neighbor and found he had an extension cord hanging on the chain link fence on the opposite side of his yard, 50' away to charge the batteries in his trailer. Sure enough, that fence had 40VAC on it. The best part is, unplugging that old extension cord made the stray voltage go away! What is most interesting is that the stray voltage that was being put into the ground on one side of his yard, was travelling under his house and showing up on the other side of the yard. It was not travelling the perimeter of the yard on the fence. This cord was also plugged into a GFCI receptacle that should not have let this occur. I inspected the cord and there were no bare wires touching the fence, just voltage leaking though the lousy cheap insulation of the cord. Buy good extension cords and replace them often if they sit outside in the sun. Don't run electrical cords through your chain link fence unless you buy a super SOW type cord. Hope this helps someone. Cam

 

[zipper]

Stray voltage can be dangerous and is a PITA to trace. I encountered this years ago on my farm with a heated s.s. automatic stock waterer. The animals would go to drink and get a small shock. Well you cannot make milk if your animals do not drink. I could not feel it with my hand, cannot remember reading on VOM, it was low, and I asked myself if I really wanted to do this, but putting my lips to waterer, I received a mild, pulsing, shock. (it was a clean waterer). It took a few hours to isolate, and the source ended up being my 48 joule fence charger. Internally the AC input and the DC output grounds/neutral were bonded. I moved the fencer to a more remote area of the farm and increased the number of grounding rods and also connected a 2' dia. galvanized culvert to the DC ground. No problems since. Previously the DC output was finding an additional path to ground by following neutral back to the PP and the massive utility grounding system.

 

[Andy S]

Sounds like the extension cord was inducing voltage on the fence, much the same way a transformer works. Those types of problems are hard to troubleshoot, good work @KXCam22 at staying with it until you solve the mystery.

 

[DeadlyFrog]

Extension cord containing a neutral will not induce magnetic flux to induce voltage onto the fence. The neutral will have an opposite magnetic field and the net field will be basicly zero. The cause of the voltage was most likely due to a poor ground at the source the cord was feeding.

 

[seadude]

GFCI didn't trip because voltage wasn't leaking to that circuit's ground. Check that cord's insulation again and I bet you find a worn spot!

 

[KXCam22]

I think the Gfci should have tripped since it was putting current into the ground that should have reached the house grounding rod and completed the path. Its getting replaced. Cam.

Ps i will happily fix it for him since he has a really nice pressure washer.

 

[DeadlyFrog]

Either a nick in extension or bad ground the GFI should be tripping. They will trip on a 4-5 mA difference between hot and neutral wire.

 

[Bill D]

The GFCI doesn't care where the current is leaking, it should only care that it is not returning through the neutral wire. They fail somewhat regularly and should be checked every once in a while.

The statement @DeadlyFrog made about induction is correct. That's the reason putting an amp clamp around an appliance cord will show 0 amps even while it is running.