240V 3 Phase and 240V Single Phase • OEM Panels

240V power is used in the US and parts of the world. In the US 120 / 240V 1 Phase 3 Wire is the standard for homes and 240V 3 Phase Open Delta is the standard for small buildings with large loads. In parts of the world 240V Single Phase 2 Wire is the standard for homes.

This is the most common four-wire three-phase delta service and is essentially a 240 volt, three-phase, three-wire delta service with one of the 240 volt transformer winding center tapped to provide two 120 Vac circuits, which are 180 degrees out of phase with each other.

This sounds like a 240 volt ungrounded delta system. In many older buildings there would be two services from the utility: A 240 volt three phase delta for the equipment, and a 240/120 single phase service for lighting and 120 VAC loads.

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 called "orange leg" because the wire is color-coded orange.

The service will be 120/240V, 3 phase. I asked if it's a high leg, he said closed delta and open delta are different, there is no high leg in a closed delta system and connecting to phase B is no problem. Would a 120/240V, 3 Phase closed delta service be a 3-phase, 4 wire or 3 phase, 3 wire? Would there be a neutral coming from utility?

3-phase power systems: Y (Wye) and Delta . With a 3-phase supply you have two ways of connecting a traditional 2-wire load, such as a light bulb or a server. In a Y system you can connect it between any phase (X, Y or Z) and neutral (N). In both Y and Delta systems you can also connect it between any two phases (X-Y, Y-Z or Z-X).

Ed, this is an unfair down vote and incorrect. In a delta system, the phase-to-phase voltage is the same. The B phase, or high leg only becomes a problem when you are wiring a 120V load to a panel box with a 120/240 three phase high leg delta service. The voltage across the neutral and the high-leg will be 208V.

† Separate the 120 into a single-phase panel and the 240 into a three-phase panel. † Use two single-phase transformers in open Delta. † Have a special three-phase Wye to Delta transformer manufactured. New Standard Offering A three-phase Wye to Delta transformer is now a Square D® standard product offering from Schneider Electric ...

For wires that will be 120, 208 or 240 volts, the following wiring color standards are used. It is important to note that with this type of wiring, there are multiple phases in place, ... Phase 3 - Phase 3 wiring should be blue. Neutral - Neutral wiring should be white.

There is less stress on a delta connected transformer from heavy motor starts than on a wye. And, of course, there is alot of single phase 240 V equipment as well as 240 V three phase stuff. And you need 120 V for general power and lighting, so the 120/240 V delta is pretty good for that. Of course, the 208 V high leg isn't used for anything ...