Isolation Devices

One means of isolating off-farm voltages from animals is the installation of a general purpose isolation transformer (240 volts to 120 volts) on the farm between the utility transformer and the breaker box serving the dairy parlor.

When properly installed, these devices provide complete separation of the utility primary neutral and the building's secondary neutral. This effectively prevents voltage from a grounded single-phase utility distribution system from showing up as stray voltage in the dairy parlor.

However, they're not cheap. Installation is justified where an off-farm voltage source has been identified and correction of the off-farm source is beyond control.

There are less expensive equipment alternatives. "Blockers" or "Isolators" can be placed between the utility primary neutral and the farmstead secondary neutral just like an isolation transformer. While these units are significantly cheaper, due to the way they operate, they cannot be used in large quantities on rural utility lines.