240V Single Phase, 3 Wires (Two out of phase Hot wires + Ground wire).208V Single Phase, 3 Wires (One Hot Wire from High Leg Delta + Neutral wire + Ground wire).120V Single Phase, 3 Wires (One Hot wire + Neutral wire + Ground Wire).In this kind of power distribution configuration, the following different levels of voltage are available across three wires + neutral from the commercial transformers. The transformers then reduce the level of voltage to the desired 240V, 208V and 120V applicable to the commercial buildings and industrial installations. The primary side of these three step-down transformers are connected to the 4.5k-7.2kV supply. In addition, High leg delta is not recommended if you are only interested in the 208V system as you can achieve it by Wye-Wye, three phase four wire system which provides 120V & 208V, single and three phase supply.įor high Leg delta supply, the electric power supply company installs three transformers to provide 120V, 208V and 240V (1 & 3 Phase) supply voltage levels based on the end user requirement. Utilities require the High Leg conductor in meters and box be located on the “C” Phase.The High Leg Must Terminate on the “B” Phase.Also, use the Orange color for high leg delta hot busbar (now phase “C”, previously Phase “B” – prior NEC-2008″.

Good to know: Other names used for High Leg Delta: Wild Leg, High Leg, Power Leg, Dog Leg, Orange Leg, Red Leg, Stinger Leg, Bustard Leg. How to Wire 208V & 120V, 1-Phase & 3-Phase Main Panel?.How to Wire 120V & 240V Main Panel? Breaker Box Installation.The overall wires enters to the commercial panel in still three hot including high leg delta and one neutral wire. In Open-Delta, two hot wires and one neutral wire comes from the large transformer and one hot wire as a high leg delta comes from the smaller transformer.In the delta secondary, each hot connects to two separate transformers. In Wye-Delta, The three phases or hot wires plus a center tapped neutral comes from the transformer.120V, 208V and 240V.įor high leg delta power, the electric power providers install three transformers Wye-Delta or Delta-Delta (we will discuss Wye-Delta for this tutorial due to 120V, 208V and 240V, 1 & 3 Phase Supply) or two transformers in Open delta configuration for smaller loads which still needs three phase power supply. The main advantages of the high leg delta system is that there are three types of available voltage i.e. High Leg Delta (also known as Power Leg or Wild Leg) is a three phase, four wire power distribution system used in commercial buildings in North America especially in rural and older installations. Wiring Color Codes for High Leg Delta Panel:.How to Wire 240V, 3-Phase Circuits & Breakers?.How to Wire 240V, 1-Phase Circuits & Breakers?.How to Wire High Leg Delta, 208V, 1-Phase Circuits & Breakers?.How to Wire 120V, 1-Phase Circuits & Breakers?.

Transformer wiring color code