What may be important in this setup is. (PE protective earth) The cable from the transformer has a common N and PE (TNC) From the main panel, the N and the PE are splitted, so the rest of the building are TNS. The PE are bonded to pipes, and other metallic parts of the building where so are. N are never grounded after the main panel. N are deemed to be treated as a live wire, and all circuit breakers are multipole, and senses current in, and breakes N to. In this building all branches are protected with combined GFCI and breakers. All light switches breaks both live and renewal to bathrooms etc. We still use Schuko and they are unpolarized. The North American AFCI are not used at all here.
What may be important in this setup is. (PE protective earth) The cable from the transformer has a common N and PE (TNC) From the main panel, the N and the PE are splitted, so the rest of the building are TNS. The PE are bonded to pipes, and other metallic parts of the building where so are. N are never grounded after the main panel. N are deemed to be treated as a live wire, and all circuit breakers are multipole, and senses current in, and breakes N to. In this building all branches are protected with combined GFCI and breakers. All light switches breaks both live and renewal to bathrooms etc. We still use Schuko and they are unpolarized. The North American AFCI are not used at all here.
Great info.
TN-C should be avoided anywhere in the system for a variety of reasons. Yes it is commonly used in Europe and USA, but has downfalls. Some of the current flows through the earth producing elevated magnetic fields and step touch potentials (stray voltage)
This are definitely interesting, and it was detected currents in the ground in Oslo when the subway in Stockholm in 1950 was started. (417 kilometers away and supplied with 750V DC)
Still this are considered as a non existing problem.
I'm a educated as a mechanical engineer, but have dealt pretty much with electro...
When we consider our traditions with IT systems, these problems are not of importance .... ????
I see lots of equal sides to your 277/480V systems, and your 208 delta's
I don't think TN-S is systematically used in any country of the world these days since it simply isn't cost-effective. It's either TT (at the cost of high loop impedance) or TN-C (at the cost of stray current issues).
Berlin sort of had TN-S for a while because some areas were supplied with 127/220 V and the PEN was only used as an earth conductor since there were no 127 V loads.
Most places had single-phase meters only and 220 V loads were connected across the two lives. However, only one of the lives was measured, so thrifty people connected one wire of a socket to the central heating pipes or cold water plumbing, thus creating their own neutral, and plugged in stuff set to 127 V. Voila, free power if connected to the right leg of the supply! Illegal and unsafe of course, but there are always some morons, no matter where you go.
