About a year ago, a conglomeration of Minnesota utilities and a few Minnesota farm organizations touted a guide that was supposed to reflect a consensus regarding proper testing for harmful stray voltage. This publication is the Minnesota Stray Voltage Guide or MSVG.
Recent research on a Minnesota farm has completely discredited the tests advocated in the MSVG. This research proves the "guide" is useless to accurately measure stray voltage. And, using the test protocol set out in MSVG invariably significantly understates electric current at cow contact points.
Because the MSVG was strongly supported by utilities, this conclusion is not surprising. However, the results of the recent study are shocking because they prove that test results using the test protocol in the MSVG understate actual harmful current by 2-3 times the measurements.
Farmers who suspect stray voltage typically call their utility for free testing. The responding utility will then test for stray voltage using the MSVG. The utility will show the complaining farmer the glossy brochure in order to get them to trust the test results in advance. WARNING TO FARMERS!! Don't trust the results the utility gives to you. They are not reliable and will greatly understate harmful electric current affecting your cows!
The main reason the MSVG protocol is unreliable is because it requires the use of a 500-ohm resistor as part of the test circuit. This resistor is intended to represent resistance of the cow in the test circuit. There is no literature citing actual testing that supports using a 500-ohm resistor. Even the testing done 40 years ago, when free stall barns were not prevalent, does not support use of a 500-ohm resistor. In today's modern free stall barns, cows are often in a very electrically conductive environment. Lanes in free stall facilities often have water, manure and urine in contact with cow hooves, greatly lowering resistance.
The recent testing showed average cow resistance at 208 ohms, with the most sensitive cows at 160 ohms. Because a margin of safety is required, a 150-ohm resistor is recommended for cow contact testing. Farmers should insist upon using a 150-ohm resistor for any electrical testing on their farm.
Bird, Jacobsen & Stevens, P.C. handles stray voltage litigation nationwide. If you suspect stray voltage is harming your livestock operation, give us a call for a free consultation. We have helped many farmers seek relief for lost income.