Re: 110, 115, 117, 120 or 125 VAC ??? (208 vs 230)

From: 	John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: 	Wednesday, January 07, 1998 2:16 PM
To: 	Tesla List
Subject: 	Re: 110, 115, 117, 120 or 125 VAC ??? (208 vs 230)

At 09:04 PM 1/4/98 +0000, you wrote:
>From: 	Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
>Sent: 	Sunday, January 04, 1998 12:49 PM
>To: 	Tesla List
>Subject: 	Re: 110, 115, 117, 120 or 125 VAC ??? (208 vs 230)
>In re: 208 vs 230
>For three phase power, a common configuration for light industrial and
>office type loads is a Wye connected three phase system, with 115 Volts
>from the phase to the neutral. This works out to 208 volts between phases.
>In an office building, where the vast majority of the loads are 115 Volt,
>this works out well, providing the phase loads are balanced so you don't
>get much neutral current.

  Jim -

  Shouldn't this be 120 volts from phase to neutral giving a standard
120/208 volt three phase system for office building and industrial loads? 

    120 x sqrt 3 = 208 volts

  Residences are normally 120/240 volt single phase systems but there are
many exceptions.

  Standard motors are normally rated 208 volts three phase or 240 volts
single phase. Standard motors are also rated 120 volts single phase but
there are exceptions. 

  However, the actual voltages can vary considerably at a particular
location depending on load conditions. 

  It should be noted that when a large Tesla coil is operated on a standard
residence system the electrical capacity at the house service can have an
effect on the spark length. This means that the same Tesla coil will produce
different spark lengths at different residence locations that have different
electrical capacities. This has confused coilers in the past. Part of the
reason is because of the PERCENT IMPEDANCE of the transformer at the pole.

  John Couture