Hello,

Just want a clarification: 208v power comes from a wye connection(ie two line wires) does 240 come from a delta connection? Please explain

Regards,

L. Fudge

208/277 is typical 3 phase why connected loads. 277 is used for lighting.

Note that 208 is sqrt(3) *120.

240 is typically a delta connection, but it's also residential "single phase"

Remember that Y-Delta and Dela-Y transformations may be done using just a transformer.

Actually 277/480v is a typical why 3-phase system. There is NO such thing as 208/277v 3-phase. Not in the US that I know of at least.
120/208v is also a why 3-phase system.

120/240v 3-phase is Delta, with Line to neutral voltages of; 120, 208, 120. All line to line is 240v.

Stan you are correct, In my area voltages are 120/240, 120/208, 240delta, 480 delta, and 277/480 .. Some of these voltages will come in 3 or 4 wire entrances .. 120/208 is made off of 3 pots (transformers) using 2 legs. This is common in large apt bldgs and in commercial areas.

We had 120 sf, 277 sf (I think), 208 3 ph, 480 3 ph as built.

But there were transformers put in place to yield some odd voltages like 380/3 phase and even some 240 V single phase. And there was one odd japanease piece of equipment that needed 100 V single phase.

In that building all sorts of power was available.