I have been talking with Duquesne Light in Pittsburgh, PA about getting
3 phase to my commercial property. The field technician thinks I may
be entitled to 3 phase at no cost because of the commercial building.
However since I already have single phase service they "might" put up
the transformers for a 230 3 phase at no cost to me. I would have to
set a pole ~$600 + do the wiring. The only problem is that the 230 3
phase would not have a neutral. I could PAY for 120/208 3 phase but I
don't know the cost of that yet. So this additional service would only
be for 3 phase and I could not tap off to run my 110 outlets. I was
hoping to be able to save money and tie it all together with on bill
instead of having 2 different meters. I don't do a lot of 3 phase work
but it would be nice to have for my occasional need to run my Mill,
lathe, welder, compressor.
They indicated that I could not get 480 3-phase for some reason.
I don't want a huge bill every month and have read other stories where
people were charged a minimum per month for the utility to justify the
cost of installation.

Any thoughts would be appreciated on whether 120/208 would be more cost
effective than 230 3 phase? Most of my equipment is 230/480V

Any thoughts would be appreciated on whether 120/208 would be more cost
effective than 230 3 phase? Most of my equipment is 230/480V

Will your equipment run on 208? If not its an easy decision.

We beat this subject to death a few weeks ago...

Chuck, can you provide the thread link?

"gtslabs" wrote in message
oups.com...
I have been talking with Duquesne Light in Pittsburgh, PA about getting
3 phase to my commercial property. The field technician thinks I may
be entitled to 3 phase at no cost because of the commercial building.
However since I already have single phase service they "might" put up
the transformers for a 230 3 phase at no cost to me. I would have to
set a pole ~$600 + do the wiring. The only problem is that the 230 3
phase would not have a neutral. I could PAY for 120/208 3 phase but I
don't know the cost of that yet. So this additional service would only
be for 3 phase and I could not tap off to run my 110 outlets. I was
hoping to be able to save money and tie it all together with on bill
instead of having 2 different meters. I don't do a lot of 3 phase work
but it would be nice to have for my occasional need to run my Mill,
lathe, welder, compressor.
They indicated that I could not get 480 3-phase for some reason.
I don't want a huge bill every month and have read other stories where
people were charged a minimum per month for the utility to justify the
cost of installation.

Any thoughts would be appreciated on whether 120/208 would be more cost
effective than 230 3 phase? Most of my equipment is 230/480V


Can you justify buying a transformer to power the 110 circuits?

I have not priced them yet. But the problem with the 230 is that it
does not have a neutral wire.

In article .com, gtslabs
says...

I have not priced them yet. But the problem with the 230 is that it
does not have a neutral wire.

Why don't you get 240 volt three phase, where they center-tap
one of the transformers? Then you get 2/3 the number of
120 volt branch circuits that the 208 star setup gives.

Just stay away from the wild leg.

Jim


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"gtslabs" wrote in message
oups.com...
I have not priced them yet. But the problem with the 230 is that it
does not have a neutral wire.


There probably doesnt need for there to be a neutral on the 3 phase if the
power company doesnt supply one. The neutral for the 110 circuits will
be supplied by the step down transformer you buy.

Jerry

On 22 Jul 2005 12:28:00 -0700, "gtslabs" wrote:

I have not priced them yet. But the problem with the 230 is that it
does not have a neutral wire.

Ask the power company if you can get 120/240V "Open Delta" 3-phase,
especially if this will be the sole service to the shop - no separate
120/240V 1ph lighting panel. This is done all the time for
residential buildings when most of the load is 1Ph, but there is a
small 3Ph draw like a hydraulic elevator motor.

They install a regular (but large) 120/240V single-phase transformer
that has a normal neutral, and can also be used to supply other
neighbors with 120/240V 1ph power. The difference is they hang a
second smaller 240V single transformer next to it on the pole.

The small transformer provides the third phase, but it is somewhere
around 190V to ground instead of 120V like the other two supplied from
the large transformer - so you have to be VERY careful to mark that
"High" or "Wild" leg with orange tape as a warning. And never hook
any 120V loads to it, or you will quickly let the smoke out of
anything thats plugged in.

You can hook up 240V 1ph loads to the high leg and either of the
other two, which will balance out the loads if you have several 240V
1ph loads running at once. (Yes, the syntax sucks on the first half
of that sentence, but I dont feel like fixing it tonight.)

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

Bruce L. Bergman wrote:

On 22 Jul 2005 12:28:00 -0700, "gtslabs" wrote:


Ask the power company if you can get 120/240V "Open Delta" 3-phase,
Yuck

especially if this will be the sole service to the shop - no separate
120/240V 1ph lighting panel. This is done all the time for
residential buildings when most of the load is 1Ph, but there is a
small 3Ph draw like a hydraulic elevator motor.

Snip

You can hook up 240V 1ph loads to the high leg and either of the
other two, which will balance out the loads if you have several 240V
1ph loads running at once.

NO YOU do NOT want to do that. Connecting loads to the leg which
actually has the transformer is OK, but connecting single phase loads
across the "Open" side of the delta tends to start to collapse the
delta that you get.

Yes, the syntax sucks on the first half
of that sentence, but I dont feel like fixing it tonight.)

-- Bruce --

jk

On Sun, 24 Jul 2005 10:39:05 -0700, jk wrote:
Bruce L. Bergman wrote:

You can hook up 240V 1ph loads to the high leg and either of the
other two, which will balance out the loads if you have several 240V
1ph loads running at once.

NO YOU do NOT want to do that. Connecting loads to the leg which
actually has the transformer is OK, but connecting single phase loads
across the "Open" side of the delta tends to start to collapse the
delta that you get.

Hmmm... Never heard that one. I'll have to remember to research it
if I ever come across another Open Delta service where they've hooked
up 1Ph loads like that.

-- Bruce --
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

gtslabs wrote:

I have been talking with Duquesne Light in Pittsburgh, PA about getting
3 phase to my commercial property. The field technician thinks I may
be entitled to 3 phase at no cost because of the commercial building.
However since I already have single phase service they "might" put up
the transformers for a 230 3 phase at no cost to me. I would have to
set a pole ~$600 + do the wiring. The only problem is that the 230 3
phase would not have a neutral. I could PAY for 120/208 3 phase but I
don't know the cost of that yet. So this additional service would only
be for 3 phase and I could not tap off to run my 110 outlets. I was
hoping to be able to save money and tie it all together with on bill
instead of having 2 different meters. I don't do a lot of 3 phase work
but it would be nice to have for my occasional need to run my Mill,
lathe, welder, compressor.
They indicated that I could not get 480 3-phase for some reason.
I don't want a huge bill every month and have read other stories where
people were charged a minimum per month for the utility to justify the
cost of installation.

Any thoughts would be appreciated on whether 120/208 would be more cost
effective than 230 3 phase? Most of my equipment is 230/480V



If you already have 240/120 single phase service all the electric co.
does is hang two more pole transformers for the other leg.
They could even get away with one transformer and give you open delta.
240 center tapped delta is what you want. The center tap gives you a
neutral for the single phase 120/240.


John