> True, but the big kl10 boxes required 3-phase 440 volts.

No.  120/208V 3-phase wye at 70A/phase is all that's required of
the CPU/memory/front end, and that's how they were normally configured
for US customers.  Add more amps for the disks, tapes, and
other peripherals.  I imagine that it probably could be configured
for 240/416V 3-phase, or perhaps for 277/480V 3-phase, but neither
is required.

Note that there is no way to configure the KL10 for single phase
or split phase without completely replacing the ECL power supplies.
They really did *require* 3-phase.