Now it's starting to make sense. Power distribution....
A couple of years ago I did something similar, but not quite as large. I
fabricated bus bars from solid aluminum. In my case, I used round stock
since I wanted to shrink large sleeving over the bars easily. (There were
many reasons thatthis was a good idea - too many to mention here.)

For the current levels you are talking about, I believe there are basically
two choices. Forgive me if I'm a bit rusty on this, but I'll describr it the
best way I can recall. If you need a lot of flexibility and don't care about
insulation, braided, uninsulated copper cable that looks a lot like huge
solder wick works. Soldered or brazed ends allow for good terminations. The
most reliable method is to fab bus bar terminators with the needed angles
and bends to go from trans to bar run.
Since this is for a travelling road show, temporary office or housing, or
some such thing, you might just want to use plain old cheap, ugly aluminum
wire. The NEC allows 545A through #500MCM (three sizes larger than  #0000)
wire that is rated for 194C, like THHN. Two pulls of this stuff for each leg
with the proper goop and squeeze terminations should do the trick safely,
legally, and least-expensively. It will also make it easy to add additional
fusing or disconnects. Be sure to de-rate for increased ambient temperatures
above 30C if you decide to go with some other combination of wires if the
ampacity comes closer to your max load.

I used some data from a bus bar manufacturer's site that is no longer
available, and it proved to be good info. I believe now there is a fairly
new resource at www.busbar.org or some such place....


Sounds like my kind of fun.

Chris

ps:

How will you make sure the transformer doesn't melt down from the imbalanced
loads you mentioned? This makes for another nice PIC project that I'd love
to........well, put on the list...

c

> -
> ahhh..what IS he trying to do...
>
> Chris is right in the fact that you should try to keep the
> voltage up and
> the curent down, but now its the distribution side of a transformer.
>
> The feed is 480V/277 Wye but I need around 2000 Amps of
> 120VAC. Yep, heard
> me right.
>
> So, the plan is...HIRE an electrician to tap off the feed, into a
> disconnect, and then from there, feed to a 300KvA transformer, which
> generates three legs of 120VAC, single phase. Each leg can
> supply up to 833
> Amps.  From the transformer, it feeds several 200A subpanels.
>  The neutral
> is double sized, to handle currents because non-linear loads.
>
> Its the distribution from the transformer to each of the panels.
>
> My thoughts are to use a busbar of sorts, or some large piece
> of Al that is
> drilled and tapped for the connections of the 4/0 wire.  I
> was just working
> on how to go from the transformer to the bus bars (solid Al
> or copper I
> suppose).  Distances will be SHORT, very short...
>
> And its all a temporary installation, up for about a month.
> The only safety
> issue is from the transformer distribution to each of the
> panels, but it
> might be under a raised floor so hopefully will be out of
> sight, out of
> touch...
>
>

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