Greg Freemyer wrote:
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 standard household supply here has one more phase, otherwise the same.
The neutral & ground are actually tied together inside the circuit breaker panel.
Not here, not at all. Any current running to ground is a fault, and will cause the residual-current circuit breaker to pop. According to wikipedia, it is called a "Ground Fault Circuit Interrupter" where you live.
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.
Wow. I'm familiar with the ground spike and the clamp on the cold water pipe, but not the rest.
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.
Right, same here.
The neutral/return is meant to carry current routinely.
Right. So why are they tied together in the circuit breaker panel?
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.
Right - dunno if I would call that perfect, for the single phase circuit it's just normal. In the 3-phase setup, with a perfectly balanced load, you have no return current on the neutral.
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.
A bit out of my field, but I don't think so. Current running to ground will cause the FI Schultzschalter to pop. One of these: http://w3.usa.siemens.com/powerdistribution/us/en/product-portfolio/circuit-... http://www.conrad.ch/ce/de/product/628056?insert=UP&WT.mc_id=googleshopping_b2c_chd&WT.srch=1&gclid=CLfb1t6AmL4CFZShtAodgyoAaw http://www.distrelec.ch/de/FI-Schutzschalter-63-A-300-mA-4-polig-415-VAC-Sch... -- Per Jessen, Zürich (18.1°C) http://www.dns24.ch/ - your free DNS host, made in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org