23 Nov
2014
23 Nov
'14
9:53 a.m.
On Sun, Nov 23, 2014, at 10:33, Holm Tiffe wrote:
Hmm, not that effective ehy?
We also have 4 wires here, 3 phases and one neutral (Star Point)
After an Security Device, the RCD it gets split to 5 wires: 3 ?hases, the
neutral and an earth line that's connected to the metal enclosure of
connected devices. In case of an isolation failure this prevents any
injury
of persons and the RCD will pop off the power if one of the phases put
more
than 30mA (thats common) in the eart line.
The four wires in the US are two phases, one neutral, and one ground
(for the enclosure). The neutral is used for single-phase components of
the device. Older devices, with only three wires, sometimes used the
neutral for the enclosure grounding (other times they would use the
house's plumbing for it), which is now not allowed, specifically because
it results in current going through the same wire used for grounding,
which means residual current detection is impossible.
This kind of power is called "Split phase" because "two phase" power
refers to a different type where they are not 180 degrees apart.