High-leg delta

Common card · No. 408201

High-leg delta (also known as wild-leg, stinger leg, bastard leg, high-leg, orange-leg, red-leg, dog-leg, or midpoint-grounded delta) is a type of electrical service connection for three-phase electric power installations in North America. It is used when both single and three-phase power is desired to be supplied from a three phase transformer (or transformer bank). The three-phase power is connected in the delta configuration, and the center point of one phase is grounded. This creates both a split-phase single-phase supply (L1 or L2 to neutral on diagram at right) and three-phase (L1–L2–L3 at right). It is sometimes called orange leg because the L3 wire is required to be color-coded orange in the United States. By convention, the high leg is usually set in the center (B phase) lug in the involved panel, regardless of the L1–L2–L3 designation at the transformer.

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