Re: [CAD_CAM_EDM_DRO] Re[1]: FYI: US Home Voltage system

In a message dated 10/3/00 3:24:38 PM Mountain Daylight Time,
Ian@... writes:

<< realisation from what has been said that you may have two phase power
to your homes and, even more surprising that both phases may be available at
a wall outlet! Can this be true?? >>

The power in the US is derived from a center tapped transformer, the center
tap is grounded, and the centertap and both hots are taken into the power
panel.
The two hots are at 120 volts potential with reference to the centertap, and
240 volts with reference to each other, 180 degrees phase difference. The
centertap is grounded, but is a current carrying wire if the loads on the 120
volt lines are unbalanced. It is the neutral in the system. Its color by
code is white.
At the power panel you can get 120 volts from any circuit breaker to
neutral. The panel is wired so that every other circuit breaker is on the
opposite hot wire. The reason for this is that by using a double circuit
breaker you can obtain 240 volts for a larger piece of equipment. The other
wire used in all modern systems is a green wire by code, it is a ground wire,
and only carries a current in a fault condition.
The neutral is called a grounding wire, but away from the panel it can have
some usually slight potential, however if it becomes disconnected from the
ground system at the transformer or panel, it is subject to float anywhere
depending on system loads and which hot line they are on. That makes a good
situation for blown lamps and appliances.
bill