A friend just called me with a question that I wasn't sure about. There is a tap box coming from the secondary side of the single phase transformer supplying (4) 125A services for apartment homes. The feeders are 3/0 AL. in two parallel sets. I know the secondaries from the power company don't use our ampacity table for conductor size so I'm not questioning this entirely. He wants to pull in single conductors instead of parallel. I was thinking of using Table 8. Determining the circ. mils of a 3/0 conductor (167,800) x 2 = 335,600 circ. mils A 400 MCM AL conductor is 400,000 circ. mils I suggested this as being more than equivalent to what was installed. But is it enough for the (4) 125A services? How do we determine this? Thanks in advance.