Thanks Albert, that was what I remembered when I was in the DC area but that was long ago. I looked at about 100 transformers today while I was driving around and I never saw one wired delta primary.
The other strange thing on my street is they have 3 transformers wired in parallel on that 3 wire bus with the 120/240, serving 11 homes. It is only one short stretch, the rest are the regular "maypole" with a transformer serving 2, 3 or 4 houses straight from that pole.
I suspect the bus was put in when there were only a couple scattered houses down the street (30-40 years ago) fed from one transformer and they just added transformers as the lots filled in. This is where the first few houses were built.
