4 Jan
2022
4 Jan
'22
6:43 p.m.
On Tue, Jan 4, 2022, 18:15 Jonathan Chapman via cctalk <
cctalk at classiccmp.org> wrote:
High-leg delta exists so you can have 120/240 lighting and appliance loads
in a building that consumes mostly 3-phase, like a machine shop with an
office. In most areas you aren't allowed to have more than one type of
service to a building (not sure if that's true for double-fed sites, never
seen one with two kinds though). I've heard the Power Company usually
doesn't want to install high-leg delta anymore for a variety of reasons:
the load limit, people not understanding they need to skip a breaker,
120/208Y having become the usual form of smaller service three phase, etc.
For what it's worth, the building I bought has two services installed when
it was built in 1921 - single phase 120/240 for lighting loads, and 240V
Delta for three phase loads.
It's the even more obscure corner-grounded delta, which requires even more
care and can't provide 120V power, since the phase to ground voltage is
240V.
Patrick Finnegan