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I live in Jordan. We have a 380Vp-p, star, 4-wire, earthed neutral connection to the building. We get 220V to the apartment (from one of the phases). I have recently installed an EV charging station for my car (13A charging current.) The electrician connected the station's hot wire from the building service line (used for elevator and lighting). But, for some reason, he could not return the neutral wire to the same meter. Instead, he connected it to my apartment's neutral which is connected to a different meter.

Is this configuration safe? Does it cause problems in billing?

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    In the U.S.A. this would be a major code violation, as far as safety the sources could be on separate transformers and this would create a safety issue. This just sounds crazy to me.
    – Ed Beal
    Oct 31, 2018 at 13:55
  • Are the hot and return lines in the same cable, at least, even?! Oct 31, 2018 at 23:07

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In the U.S.A. this would be a major code violation, as I commented.

I have multiple 2500kva transformers feeding different areas of my plant, 2 are close enough that I thought I would see what would happen if I hooked this configuration up pulling 20+ amps into my load. using the trip curve for the breaker I set it at 25 amps no problem, after about 3 minutes it tripped. What I did notice was that it spiked my monitor for a phase imbalance. If I would have loaded it any further I would have shut down the transformer that I returned the neutral side.

This is set for 100 amps so I am not sure why a 25 amp load gave me the first warning level. the meter only showed minor leakage and that is normal for this size system. Now I can say it is dangerous coming from different systems.

I thought I might see a mild increase in leakage from the transformer supplying the power but my equipment did not record this. I did also see on the recorded data oscillations of voltage across the load. this is a liquid load (brine type) rated at 1000 amps so it did not even get warm enough to boil. Boiling will cause oscillations.

With this information, I believe this could damage the electronics in the charger especially as the load changes on the transformer that connects to the neutral. So I still think this crazy and unsafe.

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  • This is unreadable. Can you please put in some punctuation and a couple of paragraphs?
    – longneck
    Nov 6, 2018 at 21:46

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