Reply to "TIU and power supply problem"

But what's nothing less than confusing is on the TIU's I've seen, the four 20A fuses are in the common (black terminal) path of each input TIU channel.  And since the overwhelming majority (if not ALL) layouts have a shared/common AC "black" terminal, the common current could flow thru ANY of the 4 TIU "black" terminals depending on wiring integrity.  So, in a strictly pedagogical example, in the OP's situation of 2 TIU channels, you could have 39.9 Amps of return current evenly split between the two 20 Amp fuses... and therefore NOT blowing either TIU fuse!  Remember we are just talking here!