1. Do they have a proven, step-by-step process that ensures your time and money will be well invested? The cold hard truth about stray voltage is that it may not be the source of your problem. Odd livestock behaviors, decrease in milk production, reproduction issues – those are all symptoms typical to a stray voltage problem, but in reality, they can have many causes that may be intertwined with one another. The pie chart below shows this.

Stray Voltage Figure 1

To make sure your time and money are well invested, it’s important not to jump to conclusions and do just as doctors do – perform a diagnostic before prescribing a solution.

2. Will their analysis be based on science?

It only seems like common sense, but be certain to ask the person seeking to be your stray voltage authority, “How do you identify if we have stray voltage concerns?” Make sure their answer makes sense, is based on proven principles and can be verified by unaffiliated sources.

As an example, to analyze the quantity of current likely to pass through the body of an animal, we use the following scientific data that has been compiled through industry studies over the past 30 years:

  • Perception threshold to electricity for a pig, chicken or cow = 1 mA (milliamp)
  • Sensitivity threshold to electricity for a pig, chicken or cow = 3 mA
  • Body resistance of a cow to electricity = 250 ohms

To determine a safety threshold at 60 hertz (Hz), we use Ohm’s Law:

  • Safety threshold = body resistance x sensitivity threshold
  • Cow safety threshold = 0.750 volts (V) (250 ohms x 3 mA)

What this means for you is that, if the current does not reach the levels identified for each species of animal, it is likely that stray voltage is not a major cause of production loss in your herd.

At lower levels, the animals may sense the current, but only with an awareness, not with negative consequences. This is what we call the “perception threshold,” which should never be confused with the “sensitivity threshold” (also called “safety threshold”).

3. Are their solutions accepted within the National Electric Code?

Many solutions can provide some potential relief from stray voltage concerns, but are they safe? Some actually put you and your herd at much greater risk than just stray voltage. It is only appropriate, and legal, to follow the National Electric Code (NEC) in all efforts to minimize your stray voltage concerns.

Article 250 of the NEC deals with grounding and bonding. Specifically, “250.6 Objectionable Current Flowing through the Grounding Path” is the section of this code that allows for:

If multiple neutral-to-ground connections result in an objectionable flow of current, one or more of the following shall be permitted to be made, provided that the fault current path is permanent, electrically continuous, capable of safely carrying the maximum fault likely to be imposed on it and it has sufficiently low impedance to facilitate the operation of overcurrent devices under fault conditions.

  1. Discontinue the improper neutral-to-ground connections.
  2. Change the locations of the neutral-to-ground connections.
  3. Interrupt the continuity of the conductor or conductive path interconnecting the grounding connections.
  4. Take other suitable remedial action satisfactory to the authority having jurisdiction.

4. Can the results of their solutions be measured?

If it can’t be measured, how will you know if it is corrected? Even if animal behavior improves, perhaps something else changed. Just as your physician would want to check your blood pressure and not just accept your sense that “I am feeling OK,” a stray voltage expert would want to document the before and after treatment levels of current.

To document the “before,” we perform an exhaustive analysis to quantify the current levels on your farm and document it through a detailed written report.

Even with an assessment call, sometimes this report identifies that the levels found are below those of concern for the safety level of the animals.

However, about 75 percent of the time, it is found that there are levels of current flowing that may cause discomfort and production losses in the herd.

Here is an example of what the data may look like in such problematic situations:

Stray Voltage Table 1

You will note that the “secure level” is identified at 750 mV for a dairy cow.

On this specific farm, the impedance (or resistance of the farm grounding network) was measured at 4 ohms.

By using the scientific formula of Ohm’s Law, we are able to determine the secure level of current to be 187 mA (750 mV / 4 ohms = 187 mA).

Therefore, any reading more than 187 mA will likely expose the cows to potential negative effects.

In this example, even during the minimum measurement (lowest 15-minute consecutive time period), the levels exceed our threshold.

5. Will you be able to track these results over an extended period of time?

What good is a temporary solution? As described earlier, perhaps something else changed in the dynamic cycle that is today’s farming. Whatever solution is attempted, it must be done with an eye on tomorrow’s challenges. “We fixed it” is not enough. “We remedied the current situation and will continue to monitor into the future” is a much more complete solution.

For example, we use an equalizer that has an LCD readout that gives real-time measurements of current flowing on the neutral to ground path. This means that you will be able to tell immediately if there is a fault on the system, as an alarm sounds and a warning light flashes, identifying the panel in which the problem is sensed.

6. Can they provide a list of satisfied customers?

Any service provider can make a host of claims. The proof is if the existing customers tell the same story and continue to tell that story months or years later. If the provider is very careful about whom he or she recommends you speak with, you may want to search further. PD

Rick McClenning,
  • Rick McClenning

  • U.S. National Sales Manager
  • AgriVolt