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Stray Voltage — Not Caused by Utility

Mike,

I recently was called to a cattle feed lot where they were experiencing stray voltage in excess of 9 volts at the cattle head gate. Several head of cattle had gone down and the voltage was the suspected culprit. I went through my usual routine of checking for grounding and then told the rancher of all the violations he had (not unusual for my area). They did have the equal potential pads and approaches for the cattle but they were wet and caked with debris.

As I did a process of elimination I discovered the voltage higher at several points. After shutting off the power to the whole operation, a voltage of approximately 17-20 volts was still present at my highest checkpoint. I was able to pinpoint which direction the fault was coming from by using the pole grounds and earth as my source.

Approximately 200 yards away at a new neighbor's home I pinpointed a service ground that had 30 volts. We asked the neighbor if we could shut his power off to see if the voltage was still there.

When we disconnected his service, the voltage dropped to 0. As I checked his lines I found a romex strung through the trees servicing a garage. This service had no overload protection or disconnect except for pulling the meter.

The main service point to the house was 200 feet away from the pole service. The romex (10-2w/g) was connected to the main triplex servicing the house. The romex had been stretched tight and pulled away from the tree in several spots due to growth of the trees.

I found the source of the problem when I approached the garage and saw the romex entering the building though metal corrugated siding. At the wires entrance to the building, the grounded conductor had been severed and the ungrounded conductor had faulted with the metal siding.

Since the new neighbor had not had the property very long and was just periodically working on it, he never noticed any problem. We disconnected the romex and solved the cattleman's problem.

The neighbor got off lucky, as the cattleman did not pursue damage collection. We found the problem shortly after its beginning but in that 2-3 days time the meter reading had increased 1389 kWH resulting in an added cost of only $89.00 to the neighbor. The power had only been connected to the home for 30 days. It's likely that the problem existed at the time of connection but went unnoticed till rain made it show its ugly face.

I don't know if you run into situations like this in the Florida area but we have this type of problem in Missouri all the time. Farmers and home owners with little knowledge do their own wiring having no clue as to the dangers they impose on themselves and in this case neighbors.

Keep it up Mike!

Todd Johnson
Johnson Electric LLC
Carthage, MO.

Grounding and Bonding Book — 2002

Grounding and Bonding textbook is all new and printed in full color. Loaded with detailed, color coded graphics, this text gets to the root of all problems associated with grounding and bonding.

Product Code: 02NCT2
Pages: 94
Illustrations: 206

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