STRAY VOLTAGE:

Voltages greater than 1v disturb cattle, decrease dairy cow milk production and lower the average daily gain in beef cattle. If animals are exposed long enough to voltages greater than 25v, the voltage can be fatal.

Stray voltage on farms may stem from several sources. The voltage may occur predictably throughout the day, or it may occur randomly. These factors make controlling stray voltage a major problem.

On-farm stray voltages have been traced to the following sources:
Ground faults on the farm. Voltage gradients across the ground or floor due to wires faulted in the earth. Electric fence wires shorting directly to equipment or energizing pipes and equipment.

Electrical motors and equipment can "short out" or ground fault to their outside casings. The severity can vary from a fault with no visible effect to a complete short circuit. When short circuits occur, all conductive materials, such as stainless steel milk lines and pipe fencing, become energized. Wood also can conduct electricity when it is wet. To correct the problem, faulty equipment should be repaired or replaced immediately by someone with proper training. The three-wire electrical supply line helps reduce the problem when the fault first occurs.

Voltage gradients through the earth or across a floor occur when an underground wire faults to earth. This often happens when the insulation of underground wires not rated for direct burial becomes damaged. Typically, the wires have not been buried at the proper depth. Underground wires buried many years ago are suspect, particularly if voltage gradients are detected in the earth. To correct the problem, the lines must be replaced with ones rated for direct burial.

Electric fence wires running through buildings can cause problems when building electrical wire is used. The maximum insulation rating of building electrical wire is 600 volts, which is not adequate insulation for the high voltage pulse output of a fence charger. When this type of stray voltage is suspected, look for breakdowns in the insulation that could be causing a fault to metal equipment inside a barn. To prevent this problem, use insulated wire rated beyond the maximum voltage output of the fence charger.