Stupid AC wiring question (220-ish Volts...)

[Josh Dersch]

I picked up a "large" machine* (for certain definitions of large) that's 
currently configured for 220-240V; my house at the moment lacks 220V 
receptacles.  I was already planning to get an electrician out here to 
put in some beefier wiring at some point (I have a couple of machines 
that draw 15-20A off of 120V that I'd like to be able to run) but I 
wasn't yet planning on doing 220V unless I have to.

(It looks like in theory it's possible to reconfigure the supply for 
120V but I lack the docs to do so with any level of confidence...)

I don't know if this machine works, and I'd rather not invest in 220V 
wiring quite yet unless it does.  And, let's face it, I'm spoiled and I 
demand instant gratification and I'd like to know as soon as possible if 
this machine is a basket case or not.

So:  since all this stuff is in the basement, I'm just about 15 feet 
away from the dryer, which at first glance runs off an outlet that meets 
my needs.  I even have a NEMA 10-30p plug here that I could wire up to 
the existing power cable for the computer.  But looking into it I have 
doubts that it's actually that simple; in particular since this house 
was built well before 1996 and so the outlet is not grounded; there's a 
neutral lug and two hot lugs (I assume two 120V A/C lines out of phase?) 
and I'm guessing that might not sit well with the power supply in this 
computer.

But then, I'm a rank amateur when it comes to house wiring and A/C and 
power supplies and all of that so I thought I'd ask the cctalk 
collective whether this can be made to work or if I should simply wait 
for a professional to take care of it...

Thanks as always,
Josh


* An AMT DAP 610, if you must ask.  It's an array processor from the 
late 80s, with 64x64 1-bit processors.  If the machine doesn't run I'm 
pretty much SOL for spare parts, schematics, service manuals, or 
anything beyond customer-level documentation (which I've recently 
scanned, btw, if anyone's curious...)