Here is what you have in your distribution system:

High-leg delta - Wikipedia, the free encyclopedia


This "high leg delta" setup provides the 180 degree out of phase hot leads that I mentioned above.


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Notice the two 120 waveforms are exactly 180 degree out of phase.

That is an older type set up. The newer ones dont have the high leg. The main reason is if you(as an elelctrician) put a 120V load on the High leg you would cook it. Unfortunatly because of the cost involved the older areas,with rreguards to the grid, are still running this set up.

I work in a new, not even in comercial operation yet, plant.

That set up is because the way the transformers are constructed internally. Wye Wye wound transformers have a single center point with three "legs" coming off of them, similar to the mercedes star. What that does is gives a uniform voltage across all three legs. 120 or 240.

The older style have a Delta(triangle) with a wye. This is how you can get the set up referenced above. Depending on where the "ground, or Nuetral" is tapped in will you different voltages

The high leg is not provided to any residence.

The result at the residence is as I previously stated. The two hot lines are 180 degree out of phase and measure 120V to the neutral.

As far as three phase, they waves are always 120 degrees apart. All of those motors dont need starting capacitors due to wiring. Because they are only at the most 60 degrees away from a high point. I only deal with the three phase stuff which is why I had to go get my book out:rolleyes:.

Not supposed to be that is. Strange things have happened when these transformers have been replaced.

Yes, we both know that the three phases are 120 degrees apart and that some clever machinations are necessary to get 120V single phase with 240V across the two supplied hot lines.

But, the point of the discussion, which is now settled, is the fact that nearly all residences in the US are provided with this type of setup.

..........because there was a moron involved...........:rolleyes:

Would it be because there are some industrial buildings close by that might require three phase?

Very possible.

Well Paid morons I might add:D:D

All industrial buildings are supplied with three phase.............usually 240V three phase or 480V three phase.

Depending on the building setup and transformer available, they can get 120V from the 240V system via the use of a center tap as shown above.

In my world, only squints use 208v.

Us audio guys like our balanced 240v.;)

and then we add 277vac to the mix to help everyones sanity.

All I wanted to know was how to plug in the toaster......

One nice feature of this system is that when one leg blows, you have half of your electricity but the meter doesn't work:)