[AMRadio] 220 vac

Edward B Richards zuu6k at juno.com
Sat Sep 1 19:17:34 EDT 2007


The standard and best way to wire for 120/240 is to use #10-3 (for a 30
amp circuit) with ground, cable. It will come with one each red, black,
white and green or bare, wire. At the distribution panel, connect the red
and black wires to the two hot legs, the white to the neutral buss and
the green or bare to the safety ground buss. Put a dual, locked-trip
breaker in the 2 hot legs. A 30 amp breaker for 30 amp service. The
locked-trip breakers will trip both legs even if only one leg has an
overload. It is true you only need the 2 hot legs and the safety ground,
but it would be foolish not to include the neutral for present or future
120 volt loads. At the load end use the 2 hot wires for your 240 volt
loads and connect any 120 volt loads to the neutral and either one of the
hot wires. If you have more than one 120 volt load, don't connect them
all to the same hot leg. Try to ba;lance the load between the 2 hot
wires. The bare or green safety ground wire goes to the metal cabinet,
frame, etc, that you may touch. At the distribution panel the red and
black wires are the ends of a 240 volt transformer. The White neutral is
from the center tap and grounded at the transformer and again at your
panel. These 3 wires carry the load current. The safety ground is also
grounded at your panel and only carries current in case of a fault where
one of the hot wires might touch the cabinet, frame, etc. It provides
safety to you by grounding any such a fault. Never cut the long round pin
off of an appliance or extension cord. It is there for your and your
loved-one's safety. Now that you know more than you wanted, good luck.

73 from Ed Richards K6UUZ
Simi Valley, CA. Home of 
Ronald Reagan Library
On Sat, 1 Sep 2007 15:52:00 -0500 "Rick Brashear" <rickbras at airmail.net>
> Please, help me be sure I am thinking correctly.  To hook up a 220 
> vac
> transformer to the main, I need use only the two hot legs, is this 
> correct?
> The third leg is for grounding purposes only, is this correct.  Of 
> course,
> this is single phase 220.  I have been struggling with finding a 
> temporary
> filament transformer for this GE box so much I want to be sure I 
> don't mess
> up. I found a 5 vac @ 20 amp, 220 volt tranny in the shed.  The GE 
> box is
> 115 vac, so I'll have to run a separate line for this 220 vac HV 
> filament
> transformer.  It's just a temporary setup to complete the testing 
> and
> conversion while the original transformer is being repaired.
> Thanks for any and all help and comments...
> Rick/K5IAR
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