I observed the following configuration in a factory: Power supply from a generator (400 V line-to-line) is stepped up to 11 KV (line-to-line), which is then fed to another transformer that produces a stepped-down, 2-phase output. The step-down transformer has 3 input terminals. Step-up transformer has 3 input terminals (connected to generator) and 4 output terminals (1 for neutral), which I think should have been the other way round since the supply coming from the generator has a neutral terminal as well (earthed in this case), whereas the primary of step-down transformer has no neutral terminal. Now the main question: both the neutral terminal of step-up's secondary, as well as transformer's metal body were earthed! If the other end of the circuit also had a neutral, that could have helped in carrying any unbalanced current back to transformer's neutral through the earth. But in the current scenario, do you think such a configuration could serve any purpose? I think the step-up's neutral should have been left untouched (by not attaching any conductor with it) and then there would have been no need to earth the transformer's body either.