Understanding Stray Voltage
What's new?Hydro One has recently formed a new Farm Rapid Response Team to help identify, assess, and mitigate stray voltage problems.What is stray voltage?From the normal delivery and use of electricity, a small voltage may exist between two conductive surfaces that can be simultaneously contacted by an animal. Examples of the conductive surfaces include concrete floors, metal stabling, milk pipelines, water bowls, etc. This voltage, known as-, "animal contact voltage-", "stray voltage", or "tingle voltage", usually presents no harm. However, if the voltage level is high enough, it may affect livestock behaviour and health.
What's an acceptable level of stray voltage?A great deal of research has been conducted over the past 40 years on the effect of stray voltage on farm animals. The Ontario Energy Board (OEB) has completed a comprehensive review of this research in order to determine the rules and regulations that govern stray voltage. The OEB indicates that stray voltage, measured in animal contact voltage, must not exceed 1.0 volt and if exceeded the electricity distributor must proceed with further testing to determine if its system is contributing to more than 0.5 volts to the overall animal contact voltage level.What causes Stray Voltage?Stray voltage can be caused by a wide variety of off-farm and on-farm sources:
Off-farm sourcesWhat are common signs of stray voltage and how does it affect livestock?
In a properly functioning electrical distribution system, some voltage will always exist between the neutral system (ground conductors) and the earth. The level of this neutral-to-earth voltage (NEV) can change on a daily or seasonal basis, depending on changes in electrical loading, environmental conditions and other factors such as improper grounding and neutral connections. For safety reasons, Hydro One’s neutral system is connected to a farm’s grounding system. While this bond protects people and animals from shocks caused by faulty electrical equipment and lightning strikes, it can also result in a stray voltage equal to a fraction of the NEV appearing on grounded farm equipment, such as feeders, waterers, metal stabling, metal grates and milk pipelines.
Poor or faulty wiring, improper grounding and bonding, unbalanced farm loading, overloaded circuits or panels, defective equipment or voltage from telephone lines or gas pipelines are all possible sources of stray voltage. By ensuring your system meets Electrical Safety Authority(ESA) standards, you can eliminate many stray voltage problems.
Reported symptoms for dairy cows include:
These symptoms and effects can also be the result of other non-electrical farm factors such as disease, poor nutrition, unsanitary conditions or milking equipment problems. Farmers should consider and investigate all possibilities, including stray voltage, when attempting to resolve these symptoms.What is Hydro One doing to help prevent stray voltage?We perform a number of measure to help prevent stray voltage. Some measures include ensuring the neutral and grounding systems are in good working order, balancing loads and upgrading the neutral conductor of the supply system.
Reluctance to enter the milking parlour
Reduced water or feed intake
Nervous or aggressive behaviour
Uneven and incomplete milkout
Increased somatic cell count
Lowered milk production.
If you think you have a stray voltage problemIf you believe that you have a problem with stray voltage:
- Call our Farm Rapid Response Team at 1-888-405-3778, Monday to Friday from 8:30 a.m. to 4 p.m.
- Complete the Stray Voltage Investigation Form.
- Email, fax or mail the completed form to us.
Attn: Farm Rapid Response Team
Hydro One Networks Inc.
483 Bay Street, 6th Floor, South Tower
Toronto, ON M5G 2P5