Harold and Susan Vordos wrote:


snip


And you're paying extra for the second service (meter) vs. a single
meter if you used Wye service. The whole peak meter thing can get pretty
hinky, particularly when it is based on rolling averages, not hard
setpoints. If it's based on rolling averages then a consistent lighting
load has little effect. You really have to analyze your loads to see
what is best.

Nope! Wrong again. I am paying for two services in spite of my choice of
delta over wye. *ANY* 3 phase service is considered industrial where we
live. Had I run everything through the CT can, avoiding the meter base, I'd
be paying for my power at a higher rate because I'd exceed the maximum
(demand meter). Our meter base is a 375 amp unit, so we feed both the
shop and the house from it, at a residential rate. It's simple------if I
wanted three phase service, and I did, I had to pay for two services, like
it or not (and I don't). As much as I may not like the cost, I'm very
happy to have the convenience. I explored the idea of phase converters and
quickly dismissed the idea. Way too expensive, considering the load I had
with the induction furnace. I had two choices had I chosen phase
converters-----buy one huge unit and pay for the idling current endlessly,
or buy a few small units and bring them online as needed, still paying for
idling current. It was cheaper, and far more convenient, to pay for three
phase service.

Interesting. In my former area commercial rates were lower per KWH than
residential rates. As long as you could manage your loads well enough to
avoid problems due to peak metering you could get better rates by
hanging your house off of your commercial service.

That induction furnace of yours seems to be the biggest issue no mater
which way you go. Such a massive single load makes it difficult to
optimize for peak metering.

As for phase converters, for manual machines I'd use inverter drives
instead since their costs have become quite reasonable and they don't
have an idle current issue.

For CNC machines in many cases you could modify them to run from mostly
single phase power and a smaller inverter or rotary phase converter. Not
real practical for multiple machines in a larger shop, but a workable
route for a couple machines in a home shop.


To the best of my knowledge, I chose the right service for my needs.
Considering I have nothing that is wired for 208, nor can any of it be
rewired to accommodate that voltage, I sure as hell didn't want it in the
shop. If industry today is headed that direction, and machine tools are
so wired, that's a whole different situation, and I'd have no quarrel with
the choice. With the machines I have, that wasn't one of the options, and
I sure as hell wasn't going to spring for transformers that weren't
necessary, not when all I had to do is request the right service.

It's likely that the potential issues diminish as the equipment gets
newer.



If you've got individual 50KW loads you may well be big enough to have
benefited from 480V service.

Again, a judgment call. I have one device with that load. Why would I
pay for 480 service, add an additional panel, then transform for everything
else? Personally, I think I made some excellent choices. Everything I have
runs as it should, and I haven't filled the shop with unnecessary
transformers. Idling current alone would have been expensive in the long
haul had I chosen that path. I have only one machine that *requires* 480
volts, a German made universal cylindrical grinder, which cannot be strapped
for 240 volts, or anything within reason. The only time the transformer
will be energized is when I use the machine. There will be no idling
consumption otherwise, so I won't be paying for making heat. Regardless of
your opinion, I feel I've done a damned good job of addressing the problems
at hand. Your bias against delta service seems to be a much greater
stumbling block for you than my choices are for me. Very strange, Pete.
However, I think if you visited my shop and observed how nicely it all has
come together, I think you might find yourself agreeing that I did the right
thing. :-)

If you've only got one huge load then 480 service is probably not
worthwhile.

Stepping up for the one problem grinder makes sense, just as adding
boost transformers makes sense if it's only a machine or two that need
them.

Remember, I'm not biased against delta service, I'm biased against wild
leg delta service, two different things.

I'm sure your shop is quite nice, it sounds like it's well equipped.

Were I planning a new shop with the full list of equipment to be in it,
their specs, etc. I might well decide on a service configuration that
included delta service for the machines. I would just avoid a service
configuration that included a wild leg.

Pete C.