Orono Substation Expansion - Enviromental Assessment (1)

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tfields from high voltage transmission lines. (Minnesota Public Utilities Commission,2009,Finding 40) ' To assist the public in understanding this issue,the applicant may provide information to the public, interested customers and employees. The information may references studies and provides data to help explain the relative impact of transmission line exposure to other common EMF exposures, and allow individuals to make informed decisions regarding EMF. Stray Voltage Stray voltage is an extraneous voltage that appears on grounded surfaces in buildings,barns and other structures,including utility distribution systems. Sources of stray voltage include a variety of ' on-farm wiring and grounding problems and off-farm problems related to connections on the electric distribution system. Sometimes a small voltage can develop at these grounding points and flow through the earth. This voltage is called a neutral-to-earth voltage (NEV). More precisely, stray voltage is a small voltage that is measured between two points that animals such as livestock can simultaneously come into contact with. When an animal simultaneously contacts these points a small current will flow through the animal (Fick and Surbrook,n.d.).These NEV currents may contribute to an excess of acceptable current in a livestock contact area on an adjoining farm. As such,stray voltage has primarily been raised as a concern on dairy farms because it may impact operations and milk production. Stray voltages are low-level voltages and should be distinguished from shocks felt by humans. Stray voltages are not lethal. Stray voltage is by and large an issue associated with electrical distribution lines. Transmission lines do not create stray voltage as they do not directly connect to businesses,residences,or farms. ' Stray voltage (NEV) sources can be reduced in three fundamental ways:reduce the current flow on the neutral system;reduce the resistance of the neutral system;or improve the grounding of the ' neutral system. Making good electrical connections and making sure that these connections are maintained by the proper choice of wiring materials for wet and corrosive locations will reduce the resistance of the grounded neutral system and thereby reduce NEV levels. ' As indicated by Xcel Energy in its route permit application,should a customer suspect that stray voltage/NEV is a concern on their property,they can call the Xcel Energy stray voltage hotline ' (651-779-3131) and discuss the situation with an Xcel Energy technician or engineer. If warranted, an on-farm investigation will be scheduled. Xcel Energy will conduct an investigation of the distribution utility system serving the farm and the farm wiring and discuss the preliminary results ' with the customer. In most instances,recording volt meters will be set to measure activity over several days. Upon completing the analysis,an Xcel Energy engineer or technician will call the farmer to discuss the results (Xcel Energy,2011a). Induced Voltage/Contact Voltage The electric field from a transmission line in some instances can reach a nearby conductive object, ' such as a vehicle or a metal fence,which is in close proximity to the transmission line. This may induce a voltage on the object,which is dependent on many factors,including the weather conditions,object shape,size,orientation,capacitance and location along the right-of-way. If these objects are insulated or semi-insulated from the ground and a person touches them,a small current ' would pass through the person's body to the ground. This touch may be accompanied by a spark ' Environmental Assessment PUC Docket E002/TL-11-223 Page 37