In a message dated 2/23/05 7:48:33 AM Eastern Standard Time, 
olin_piclist@embedinc.com writes:

> No, because the return currents from the two 110V legs are out of phase and
> will therefore cancel.  The neutral wire only handles the difference between
> the two 110V hot wires, which means worst case it needs to handle the same
> current as a hot lead if the entire load is only on one of the 110V phases.
> 

Dead on,  even in three phase applications the neutral is the same size as 
the hot lines.  But, in most cases the ground line is smaller and that is 
allowed by code for the most part.  However, personally I prefer to have my ground 
the same as the other wiring, just a preference of mine. 

Regarding house wiring, you are just using 2 leads of the three phase line 
and then using a center tapped transformer to create the neutral and therefore 
110 Vac for most home applications.  In that case because the 220 lines are out 
of phase, then the neutral can be the same size as the hot leads.  Now, if 
you have 220 volts with no neutral, just the two hot leads and you are not 
certain if there is a neutral somewhere in the circuit that is attached to ground, 
then you will NOT get 110 between those 220 volt lines and ground, it will be 
the 220 divided by the square root of 3, or close to that.  However, if you 
are in an industrial area and happen to have a "Y" configuration then you should 
have a neutral and you would get 110 between one of the legs and the neutral, 
as long as it is NOT 440 three phase of course.  Now, having said all of 
that, one can often operate 110 volt devices even on the higher voltage between 
ground and one of the three phase lines as many 110 devices are rated 120 and 
can often handle a 10% variation in voltage.  You would get something like 125 
to 130 volts between one leg of a 220 three phase line and ground, if there is 
no neutral.

Hope this helps and doesn't confuse.

Randy Abernathy

4626 Old Stilesboro Road NW
Acworth, GA 30101
Ph / Fax: 770-974-5295
E-mail: cnc002@aol.com

I furnish technical support, repair, and other related services for your 
industrial woodworking machinery. My background as Senior Service Engineer for the 
SCMI Group for nearly fifteen years with factory training, combines with my 
extensive background in electronics, mechanics, pneumatics, electrical and CNC 
machinery to offer you needed support for your machinery. 

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