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

Brent Hilpert hilpert at
Thu Feb 5 22:54:44 CST 2015

In the scenario being discussed, there should be no current flowing in the dryer neutral wire, so the only place there should be a voltage drop would be around the neutral-bus-bar/ground-link in the panel, which should be negligible - unless the dryer is linked off a sub-panel where there would an opportunity for other loads on the sub-panel to produce a voltage drop on the neutral back to the main panel.

On 2015-Feb-05, at 8:31 PM, Jerry Wright wrote:

> Josh,, The neutral   and  ground are hooked together in the panel. so basically they are the same..   the dryer plug gives you a couple  of good 30 amp 110/120 circuits or
> 1 good 220/240 volt circuit.   The difference is the Neutral is not at ground voltage. it is loaded some from the load lines,  but for what you are doing, make   the connection and give it a try
> On Thursday, February 5, 2015 7:28 PM, Josh Dersch <derschjo at> wrote:
> 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...)

More information about the cctech mailing list