"Pete C." wrote in message
...
Harold and Susan Vordos wrote:

s
"Pete C." wrote in message
...
Harold and Susan Vordos wrote:
snip---



You keep saying that, as if there's other types. I've heard of a
corner
grounded delta (but don't understand how it relates to voltage), but as
far
as I know, they all have a wild leg if you shoot for 120V. Is there
something I don't know or understand? The moment you introduce the
neutral, seems to me you're bound to have only two phases that yield
120V
unless your wired wye. (That should have said *you're*, not your. H)

A pure delta service does not have a neutral at all. There is no 120v on
it, only 240v phase to phase. The corner ground is strictly for safety
purposes to limit the relative voltage from any phase to ground. This
can make that phase look superficially like a neutral, but it is not.

OK, that makes sense. From what you're saying, then, is that you don't
object to delta so long as you don't derive any 120V from it aside from
transforming. For all practical purposes, that's what I'm doing this
time, using my delta service only for 3 phase, with all (except one place)
of the 120V stuff coming from my single phase panel, which I would have done
anyway, due to the demand meter. However, using the delta service for 120V
is done routinely, as you likely know. The only real disadvantage I am
aware of is the lost space in the panel---the B phase, the wild leg.
Byond that, I don't see any issues. As far as I'm concerned, changing to
208 volts is a greater sacrifice than losing the few spaces, at least with
the equipment I own.




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.

OK---fill me in, then. What type of service would it be? Strictly 240
V?
That's what I have now. I do *not* use my 3 phase for single phase
service*, although when I wire my mill permanently, I will have single
phase
for the power feed and work light, but only there. I'll do that so I
can
keep the wires away from the bottom of the machine. I have the box
overhead, almost directly over the motor on the mill. 12' ceiling.
You
can do that when you have a 5 wire system. Everything else is strictly
3
wires, plus ground. Do you still have heartburn over my wiring?

How are you going to wire the mill? Separate conduit from each panel to
separate boxes overhead and separate drops to the mill head and the
light / power feed? Is the neutral present in your three phase panel so
you can do a single feed from there? You can't or at least shouldn't
(I'd have to look in the code book) combine circuits fed from separate
breakers in separate panels in a single conduit run to the mill.

As I said, my 3 phase service is 5 wire, meaning it is capable of delivering
120V single phase, per code. In the case of the mill, I'll take advantage
of that and use the neutral, tapping either the A or C phase for the 120V.
I have two boxes, side by side, coupled with a short nipple. One will have
the three phase outlet for the mill, the other will have the single phase
120V, all fed from the same breaker, in the same conduit. It's clean and
easy. Remember, we're dealing with only a few amps, tops. I'm not
concerned about balancing the load in this case.


For the mill I would likely feed it strictly three phase and locally
derive the 120v with a small transformer. Of course I got about a dozen
1 KVA 240/480 x 120/240 transformers for about $10 each brand new so
that biases the economics a bit.

Chuckle! Put one of them in the mail to me and I'll wire it that way, so
you won't worry about me and my safety! :-)

Harold