When to use: Use during panel design or troubleshooting to verify that single-phase loads are balanced across all three phases. Unbalanced panels cause neutral overcurrent, transformer overheating, and voltage unbalance — which damages motors and sensitive electronics. NEMA MG 1 recommends keeping voltage unbalance below 1%, which corresponds to roughly keeping phase load imbalance under 10%. This calculator helps you assign circuits to phases for optimal balance.