From: reynhout@cs.uri.edu
Newsgroups: sci.electronics
Subject: Re: changing 220 line to 110
Date: 12 Apr 92 17:12:51 GMT
Organization: University of Rhode Island, Computer Science Dept.

In article <JEFF.92Apr7214858@sparc38.cs.tamu.edu> Jeff@cs.tamu.edu writes:
>I need to change a 220v line to 110v line in my house.  Do I just need
>to switch the line from a 220 source at the breaker box to a 110 source
>and then change the wall socket/face plate to allow a normal grounded
>plug to be used?  It seems that this is all that would be necessary,
>however I guess the wires would be a bit heavy for 110, but would that
>make too much difference?  The line is used to power a 10k btu window
>a.c.
Wire gauge is not a problem as long as it's big ENOUGH.

>
>The old a.c. was 220V, 60Hz, 13.2/14.4 amps, and 17Kbtus.  The new one
>is rated at 115V, 60Hz, 10.3/12.6 amps, and 10Kbtus.

   Here's what to do:  The 220 is on three wires (four including ground) as
follows:   red:  hot1
         black:  hot2
         white:  neutral
          bare:  ground

   Find the breaker in the panel for this line.  Kill all the power to the 
panel with the master breaker (or the feed breaker, depending on how your
wiring is done.)  You COULD simply disconnect one of the hots (for conformity,
you should disconnect the red one,) and use one side of the double-ganged 
breaker.  (Then connect a standard household outlet to the other end, using
the white and black)

   A better way, though, would be to buy a new breaker (120v 15A) and connect
the black at the panel to this breaker.  Then do the same thing as above at
the outlet end -- leaving the red wire disconnected from EVERYTHING.

   I'm assuming that you're generally familiar with household wiring stuff,
and posted just to make sure that what you're thinking is correct.  If this
isn't true, and you really don't know what you're doing inside a breaker
panel, do yourself a favor and find help from someone who does.  It's not
terribly unsafe if you use a little common sense, but we all make mistakes,
and a mistake with line voltage could be a very costly one.

   *** Unrelated to above, but not worth a seperate posting:
   I used to work for American Power Conversion, a manufacturer of Uninter-
ruptible Power Supplies (or so their PR people claim.  I happen to know that
they're really Standby PSes, but that's another issue entirely.)

   Anyway, in the course of working on PSes that weren't operating properly,
I would occasionally hit myself with unfused 120vac  (and, on the overseas
models, 240vac)  While certainly unpleasant, it was in no way debilitating.
I'm not dead, I don't *feel* affected, et cetera.
   I know that internal body resistance varies from person to person and
from day to day...Am I just very resistive?  (Some people there would 
certainly say so :-)  I took a couple of hits with 240 from my left hand
to my grounded right hand.  Straight through the sensitive spot.

   Any thoughts?

PS: no flames on carelessness.  In working on defective equipment, it is
quite possible to surprise oneself with exactly where line voltage (or 
inverter-supplied voltage) can be found.  In working on defective equipment
ten hours a day six days a week, it's quite easy to surprise oneself rather
often.

   Andrew
-- 
   Andrew <reynhout@cs.uri.edu>