Re: 110, 115, 117, 120 or 125 VAC ??? (208 vs 230)
From: Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: Friday, January 09, 1998 9:49 AM
To: Tesla List
Subject: 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)
> 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
Yes... my mistake.
> Standard motors are normally rated 208 volts three phase or 240 volts
> single phase.
Not generally so. The typical motor is 230/460 dual voltage, and for a
slight premium in price, you can get 208-230/460 (more copper, slightly
different core). This is for motors of 2 HP and up, I might add. Check out
the Baldor or Grainger catalogs..
> It should be noted that when a large Tesla coil is operated on a
> 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
> different spark lengths at different residence locations that have
> electrical capacities. This has confused coilers in the past. Part of the
> reason is because of the PERCENT IMPEDANCE of the transformer at the
As well as the impedance of the feeder line from the transformer to the
house, which may be many hundreds of feet long.