> 120V 3-phase delta wiring weird

Imho this is not so weird, it saves one wire. Most places outside US/CAN
seem to be wired as 3-phase wye (especially 220V countries), with some
loads having only one phase, some two, and some three (not necessarily
from the same wye !). This happens as electricians add capability on
demand during the life of a building. The wye center may be grounded or
not, at the panel, or farther outside. Here we have mandatory GFI so the
center is grounded outside or at the panel, before the GFI breaker. Even
so it is not uncommon to have 5-20V between neutral and P.G. at enough
amps to run small lamps on it, and circuits imported from other countries
that rely on P.G == Neutral get fried regularly. The large difference is
usually due to air conditioners which are very popular here and which
often draw starting currents on the order of over 50A for a short time
(the house lights usually dim when this happens).

Peter

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