Voltage unbalance in a four-wire or “high leg” delta can be tricky to measure. A 4-wire delta often involves unbalanced impedances, and phase shifts in the hot leg are common.
Unbalance measurements referenced to the neutral require scaling for the hot leg, and can be misleadingly low for delta-connected loads. A technique for computing true line voltage unbalance from neutral-referenced readings is shown, along with a real-world example.