Jon Elson wrote in message ...
Peter H. wrote:

They will be hanging three transformers (2 additional, but three new ones).



Then, you'll have *true* three phase.



What does this mean to me when I go about getting things wired up? Do I still
have the infamous "wild" leg, or do I even care if I pull all of my single
phase loads off the 2 other transformers?



No "high leg" problem here.

Do tell the utility if you want 120/240 volt Delta or 120/208 volt Wye, though.


Wait a minute! If he has a 240 V Delta system, there will be NO 120
volt power
available anywhere! There will be 3 wires, with 240 V between any
combination
of them. No neutral will be supplied on the delta system.

The former is good for those cases where you have just lighting on 120 as only
one of the three transformers can be used for 120/240 single-phase.


Unless you have a lot of 240 V single phase loads, or motors that must have
240, and cannot be run on 208 V, you would do best, in most cases, with a
120/208 V Wye system.

If the power company will only install 240 V delta power, you will then
need a
240:120 V step-down transformer. (Since they are going to put in
3-phase FREE,
you may do very well to get a used dry-type stepdown transformer to provide
your 120 V supply for lighting, computers, hand tools, etc. Figure out your
worst-case 120 V load, and size the transformer a little above that. If you
can't find one big one, then get 2 or 3 smaller ones, and you can have
several
separate 120 V feeds. Smaller stepdown transformers in the 2-5 KVA range
can often be had from scrapyards for the scrap metal value.

Jon

Perhaps I need to clarify....

They are putting in a 240V Delta xfrmr, with 2 piggy backed off from
it to provide the single phase service.

My understanding is this - all power will go through the 3 ph xfrmr.
The single phase will be tapped off from the 2 piggy backed xfrmrs.
Can't quite figure out why there are 2 "secondary" xfrmrs. Shouldn't
it be a single 240 single phase and just center tap it to give me my
120 service? Or is it a balancing issue?

As for the main panel... Talking to a electrical supplier, their
recommendation for service cable for 400A was to use dual 3/0. Can I
split this to 2 panels and be legal as far as code? Reason for doing
this would be that I can get 200A 3 ph panels for free. Not sure
about a 400A. I will have to check with my source on that.

Thanks

Jeridiah