On Dec 2, 2010, at 11:06 AM, Owen DeLong wrote: > It is not uncommon for three-phase panels to be different and have > all three phases in the panel each phase feeding every third breaker > slot.
I was just recently trying to explain this to a European friend who thought I was hallucinating this system, so I took a picture. http://dl.dropbox.com/u/230717/temp/208YPanel.jpg That's a picture of one of the breaker boxes in our office, showing what you described. There are 3 phases coming into the panel, each a different coil off a Y transformer, as well as a "neutral". Those are the 4 black wires you see at the bottom. You can see how the three hot phases are staggered as they go up the breaker rails. For standard 110V service, you use a single-wide breaker and send one hot phase + neutral and you get 110V. The difference between two phases is 208 volts though, so you use a double wide breaker and can send to device without using a neutral wire. Just 2 hots and a ground. If that's all you're doing (you don't need legacy 110V service anywhere) you skip the ground wire going into the panel entirely. -- Kevin
