It is important to understand what causes and how to fix voltage unbalance when dealing with a 3-phase electrical system. An example used in this article, for instance, shows a 480V nominal system that may measure phase-to-phase voltage: 463V, 482V, and 474V. The voltage unbalance will create a current unbalance or magnify any present current unbalance. According to the National Electrical Manufacturers Association (NEMA), for every 1% of voltage unbalance, 6% to 10% of current unbalance will be created. Voltage unbalances can be caused by several issues in the electric utility system. There is also a simple formula that can be used when taking phase-to-phase voltage measurements. 

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