I'd be surprised, because I had 3 8650s at one time and did the breaker panels / input power for them. I don't recall any warning in the site prep or installation guides about ensuring correct phasing. Plus, there is an airflow sensor that trips the entire system offline if there is insufficient airflow. Simply trying to slide the reusable filter out of an 86x0 will trip the airflow sensor. Trivia - the 86x0 doesn't need that ridiculously expensive Russel Stoll 60A watertight connector. I ran our first one happily on am adapter cable I made to power it fom the L21-30R receptacle we used for the 785 it replaced.
Oh, believe me, it do use the three phases that way. I should say that I can't swear US models might have been different, but I know about the one some people I know wired up backwards. And yes, there is an airflow sensor that trips if you wire it wrong. They were also creative enough to wire around it, since they didn't realize the fans were running the wrong way. I can't remember if they even managed to cause some permanent damage to the machine. I could ask if they remember. It was a little more than 20 years ago now...
The fans in the 86x0 machines are pretty massive. It's a veritable storm behind the machine. But I suspect you already knew that.
And since Update still have it's 8650, I can even check that one as soon as I am in Sweden next time.
The one we have had an oversized power connection, but nothing close to what you describe. But it had a 32A 3phase connector of the standard style in europe. But we put an adaptor on to a 16A version, which works just fine. Rumours had it that they put that connector on to be able to just plug it in at the same installation as IBM machines they hoped to replace, which needed the 32A.
But I have no idea if that is true or not.
Our DEC-2060s had ridicoluous 63A 3phase connectors, though. But I'm not sure they usually were delivered with that or not... Can't believe they really needed something like that.
Just searched through some documentation on the 86x0. Here is the best I could find on the fans:
See page 18-25 (page 445). There you see mentioned that after replacing the blower motor, one should check the rotational direction, and if it is wrong, the harness connection should be checked for reversed leads. (Block is on previous page.)
If you search through some other parts, you'll find mentioned on the power distribution, that 4 wires goes to the blower motors. 3 phases plus neutral.
So it appears to be the same on US models. Different blower motors for 60Hz and 50Hz as well.
Oh. And I forgot: removal of the filter don't trip the airflow sensor. There is a separate switch detecting if the filter is in place, and power is immediately removed if the filter is not in place. But it's a separate switch to the airflow detection. It's also documented elsewhere in that manual.
I just love the 86x0 machines. Such much nice engineering in them. Unfortunately our 8650 only have 60Mb of memory. We did try to ship the cards from you Terry, a long time ago, but they disappeared somewhere along the way in shipping. No clue ever where they ended up. But still thanks for that effort.