Stray Voltage
What is Stray Voltage?
Farm ‘stray’ or ‘tingle’ voltages are small electrical potentials between metal stabling/equipment and floor surfaces. Animals that make contact between these surfaces may receive a tingle or mild shock that disturbs the animals’ normal behaviour and can ultimately reduce the efficiency of the farming operation.
An InnPower livestock customer may ask InnPower to initiate a farm stray voltage investigation, where a livestock farm customer provides information that reasonably indicates that farm stray voltage may be adversely affecting the operation of the customer’s livestock farm.
What causes Stray Voltage?
Stray voltage can be produced by a variety of on-farm and off-farm sources.
On-Farm Sources:
Unbalanced farm electrical system loading, faulty wiring, improper or poor grounding, defective equipment or voltages from gas pipelines or telephone lines are all possible sources. InnPower’s neutral system is connected to a farm’s grounding system. While this bond protects from shocks caused by faulty electrical equipment and lightning strikes, it may result in stray voltages on grounded farm equipment such as feeders, watering devices, metal stabling, metal grates, milk pipelines and wet concrete floors.
Off-Farm Sources:
In a properly functioning electrical system, some voltage exists between the neutral system (ground conductors) and the earth. The level of this voltage can change depending on changes in environmental conditions, electrical loading, and other factors.
What are Common Effects of Stray Voltage?
Animal reactions to the presence of stray voltage may range from:
- Mild behavioural reactions such as eye blinking
- Involuntary muscle contraction or twitching
- Discomfort and or pain causing intense behavioural reactions
- Reluctance to enter milking parlour
- Reduced water or feed intake
- Lowered milk production
- Nervous or aggressive behaviour
- Uneven and incomplete milkout
- Increased mastitis
- Reduced growth
Animals may avoid certain exposure locations, which may result in reduced water intake or reduced feed intake. It may also be difficult to move or handle animals in areas of exposure.
Note: the symptoms above may also result from other conditions or illnesses. Farmers should consider and investigate all possibilities when looking for a solution.
- Any recent changes to electrical circuits, motors or hardware?
- Any recent changes or additions to barn operations?
- Any history or past precedence of stray voltage problems?
Common Ways to Reduce Stray Voltage
Common ways of reducing tingle voltage would be to reduce grounding resistance of the system grounds and system neutral and by repairing faulty electrical equipment and wiring. An alternative solution, particularly applicable to milking parlours, is the installation of an equi-potential grid. The grid consists of a welded wire mesh, embedded in the concrete of the cow platform in the parlour and in other areas where cows contact bonded stabling or feeding or water devices.
The mesh is bonded to the neutral, thereby raising all contact to the potential grids of the neutral and eliminating exposure to stray voltage. Equi-potential grids are required in new milking parlour construction under the Canadian Electric Code and are included in Canada Plan Service milking parlour plans. The grid offers the added advantage of improving system grounding and eliminating electric shock hazard for livestock on the grid from all sources including lighting.
Stray Voltage Response Procedure – Distribution System Code Appendix H
If you think you have a stray voltage problem, call InnPower Customer Service at (705) 431-4321 to set up an appointment. It is estimated that InnPower requires five business days or less following receipt of a complaint or inquiry to contact the livestock farm customer to schedule a site visit for the purpose of initiating an investigation.
What is the Current Limit for Animal Contact Current in Ontario?
According to the Distribution System Code 4.7.3 from the Ontario Energy Board, the current threshold for animal contact current is 2.0 milliamperes or 1.0 volt. If the threshold is exceeded an investigation is required. Contact InnPower to set up an appointment.
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