i have to give a customer a full 400amps at 208 volts 3 phase 4 wire.
the design is to install a 150kva step down transformer.
now since a 150kva tx. on the primary is 180amps i intend on running 3#3/0 fused at 180 amps
off the secondary side i believe {using 90degree wire }i should use 750 mcm
since i am going into a 400amp switch
750mcm at 90degree the amp rating is 535
since it 4 wire and derating at 80%
i believe it should be 535 x 0.80 x0.91{derating of 90 degree wire} i come up with 390 amps.
am i on the right track.
yes the gec is based on 250.66 and egc is based on 250.122
the design is to install a 150kva step down transformer.
now since a 150kva tx. on the primary is 180amps i intend on running 3#3/0 fused at 180 amps
off the secondary side i believe {using 90degree wire }i should use 750 mcm
since i am going into a 400amp switch
750mcm at 90degree the amp rating is 535
since it 4 wire and derating at 80%
i believe it should be 535 x 0.80 x0.91{derating of 90 degree wire} i come up with 390 amps.
am i on the right track.
yes the gec is based on 250.66 and egc is based on 250.122