On Tue, May 6, 2014 at 2:26 PM, Per Jessen <per@computer.org> wrote:
Using a 2-phase US circuit to simulate a 1-phase 220v circuit would be dangerous if there are devices that depend on one of the legs being ground.
I suspect you mean neutral instead of ground?
At least here neutral and ground are very similar. A standard US household circuit breaker panel has: phase 1 hot phase 2 hot neutral - return ground The neutral & ground are actually tied together inside the circuit breaker panel. Further, both are often connected to a copper cold water line. By code that has to happen close to where the cold water line enters the building. I know my house works that way, but there is also a second ground spike driven directly into the ground that is also tied to the circuit breaker panel ground and neutral. Thus in theory the "ground"/neutral is actually a part of the 120volt circuit. and both the ground lines and the neutral/return should have close to zero volts differential to the outside dirt (ground). The fundamental difference here is that the ground lines running to every plug don't typically carry any current except in a failure mode. The neutral/return is meant to carry current routinely. With a "class II" plug, the active legs slots are slightly different sized so that a device can know which leg is neutral (close to ground) and which leg is hot. http://upload.wikimedia.org/wikipedia/commons/d/dd/OutletPlug.jpg fyi: if a circuit breaker panel is perfectly balanced the electrons flow only in the 2 hot lines and in the neutral. No electron movement would take place in any of the ground lines including the real ground outside. Such perfect balancing is impossible to achieve so electrons are moving in and out of the earth continuously in a US system. I assume the same is true for the EU. Greg -- Greg Freemyer -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org