[rescue] argh, what did I do? (Onyx)
james at foonly.com
Wed Jan 15 14:48:21 CST 2003
On Wed, 15 Jan 2003, Jochen Kunz wrote:
> Is three phase power really that uncommon in the USA??? In good old
> Germany we have 230 V @ 16 A three phase in every kitchen to feed the
> electric stove. It is also common in home workshops to power various
> biger e-motor driven machinery and welding transformers.
For businesses, especially in industrial areas, it's reasonably easy to
get. It's possible to get in many residential areas, but it's not common
and if the power company doesn't have 3-phase distribution gear nearby to
feed you from, you generally end up paying the cost for any infrastructure
upgrades necessary. You pay commercial rates (which are frequently
higher) and in many cases have a significant minimum monthly payment.
Usual residential power distribution in the USA is center-tapped 240V 1ph.
The 2 120V legs are broken out to individual outlets, and 240V is used
directly to power appliances such as electric dryers, water heaters,
stoves and the like. Many houses use natural gas for these appliances
instead and get away without any direct need for 240V at all.
Usual 3-phase distribution is either 120V/208V Wye (120V from each phase
to neutral, 208V phase to phase) or 240V delta (240V phase to phase).
"High leg" Delta (where neutral is center-tapped in one of the 240V
stretches, giving a pair of 120V legs from neutral) is much less common
now and many power companies are getting away from it due to phase
FYI: I paid $0.21/kw-hr in 2001 (northern California).
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