electrical installation

[mosman]

Can anyone tell me if i made a mistake somewhere?
600V 3 phase delta dropped down to 240/120V
that will be feeding a small shop.
Load
1 50A welder @ 240V = 12000VA
1 30A trailer @ 240V= 7200VA
8 15A circuits@ 120V= 14400VA
1 15A lighting@ 120V= 1800VA
1 100A future @ 240V= 24000VA
--------
59.4KVA full load
I could use 55KVA X-MER
55KVA/(600*1.732)=52.92*125%=66.15
Table 2 = #4awg primary cable
overcurrent protection=52.92*125%=66.15A
therfore A 70A c/b would be used.
SECONDARY
55KVA/240V=229A*125%=286.45
Table 2 = #300awg secondary cable
1/0 equipment ground.
300awg will be brought out of the building and into a 225A splitter then out of the splitter into a fused disconnect and then into a 225A panel (bus rating)
what size of cable and fuses should i use once i leave the splitter and am I missing anything?
Thanks mosman

[electric-ed]

Hi Mosman,

It appears that you have calculated the primary correctly, however, the secondary has been calculated as if it were a single phase circuit.
<BLOCKQUOTE><font size=2 face="Verdana, Helvetica, sans-serif">quote:</font><table border="0" width="90%" bgcolor="#333333" cellspacing="1" cellpadding="0"><tr><td width="100%"><table border="0" width="100%" cellspacing="0" cellpadding="2" bgcolor="#FF9900"><tr><td width="100%" bgcolor=""><font size=2 face="Verdana, Helvetica, sans-serif">"dropped down to 240/120V"</font></td></tr></table></td></tr></table></BLOCKQUOTE>
Did you intend to run a 120/240 volt single phase feeder to the splitter?

Ed

[mosman]

Hi ed thanks for responding
yes I do intend to run a single phase feeder to the splitter because of the welder is a 50A 240v unit and I don't think that it would work properly on 208V (right?!?!?!)the trailer also has a 30A 240V panel.
Thanks
Mosman

[bigrockk]

Dropping down to 240/120 as opposed to 208/120 may cause you some capacity and balancing problems with your xformer.
Check out this link for more info.

http://www.federalpacific.com/univer.../chapter3.html