On Sat, 6 Jan 2018 13:07:52 -0500, "Mr. Luddite"
wrote:

On 1/6/2018 12:39 PM, wrote:

OK that makes more sense. The service side will usually be medium
voltage and I agree it is common not to have that grounded if it is
delta. We usually see wye distribution here once it gets down to
street level tho. (one grounded conductor and one ungrounded "hot" on
the pole).
http://gfretwell.com/electrical/transformer.jpg
The power line behind my house is 2 medium voltage and 1 high voltage
line going south. The medium voltage gets tapped off along the way and
the high voltage goes all the way to Naples. They are all ungrounded
delta.
The service side is actually regulated be the NESC, not the NEC and
they have different rules. That is why your service drop can be #2
1350 aluminum and once you take over from the service point you need
to go with 2/0 cu or 4/0 al.

Your power on the customer side was corner grounded delta.
Legally they could have brought that grounded leg to your panels in
white wire and used 2 pole breakers on the ungrounded conductors.
That is when it gets confusing. I did see that in sewer system lift
pumps (240v corner grounded delta). That is the only place. The line
to neutral loads were 240v as were the line to line. It took me a
minute to figure out exactly what was going on there.



About 70 percent of our systems were designed for 480v and the customer
was responsible for providing a service drop near where the system would
be installed. Never saw a two pole breaker and a neutral in all the
years we built systems. Would have confused me. :-) Fortunately we
had a PE (EE) on our engineering staff who reviewed all our electrical
drawings to make sure we were compliant. In our technical proposal we
would identify the service requirements which were typically, 480v, 3
phase and then whatever the total power consumption was (i.e. 25kva or
whatever it was).

Same with the systems that ran on 208v when 480 was not available. We
just required 208v, 3 phase and again identified the total power
consumption. We provided a control transformer for 120v, even in the
systems that ran on 208 wye. There was a reason for this. I've seen
systems built by others who got the 120v control power from the service
panel and, if something failed in the vacuum deposition system, like a
fuse or motor starter heater in the power panel the system might still
try to run, creating a dangerous situation. We wired control power
through aux contacts on all the motor starters or sub system contactors
so if one tripped, control power was lost and the system defaulted to a
"safe mode" with all valves automatically closing under air power.

This discussion is bringing back a lot of memories. :-)

I am not sure when they decided all "grounded" conductors should be
white but it was certainly before the 80s.
Corner delta was always the strange duck tho and I have heard sparkies
say strange stuff about it like it is "hot as hell". I ask, "in
reference to what"?
A grounded conductor is still a grounded conductor, no matter which
tap on the transformer you choose to ground.
Once you do that, you can use 2 pole breakers on corner delta. They
need to be delta rated tho. (essentially that means they are rated
line to line, not line to neutral like general purpose breakers).
Normally you do not put overcurrent protection or switches in grounded
conductors and the exception is when all poles open simultaneously.
That is how they get away with 2 pole stuff.
Corner delta is also a reason why we say "grounded conductor" and not
neutral, which is really not defined in the code anyway. This is a
regular current carrying conductor, that just happens to be grounded.
200.6 still says it should be white or gray.

"200.6 Means of Identifying Grounded Conductors.
(A) Sizes 6 AWG or Smaller. An insulated grounded conductor of 6 AWG
or smaller shall be identified by a continuous white or gray outer
finish".
(larger than #6 can use phasing tape, paint or any other "distinctive"
marking method since the insulation will usually be black)