I sketched the following schematic from a motor controller board that has to be operated at 220V from L1 to L2. The earth wire is connected to the chassis of the machine. Where I live, it's common to see ground and neutral at the same point for 110V machines. My 220V connection has 3 wires: L1, L2, and neutral (not ground). That is, from L1/L2 to neutral I have 110V. So, my question about the schematic is: what if I connect the earth point of the motor controller to the neutral point of my 220V outlet? I would have 110V between L1/L2 and earth and that means the neutral would be attached to the chassis. In this case, as I do not have ground on my 220V outlet, should I disconnect the chassis from the neutral?

enter image description here



simulate this circuit – Schematic created using CircuitLab

Can you decide now, what you can or shall not do?

  • \$\begingroup\$ I'm still kind of confused. I think I just shouldn't connect the outlet neutral to the equipment earth/ground. \$\endgroup\$ – Blue_Electronx Jan 10 '19 at 16:28
  • \$\begingroup\$ Any Neutral fault currents such as arcing may induce such surges. It is normal to use Neutral only then ground the isolated frame only. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 10 '19 at 16:34

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