I am not an electrical engineer and do not have a deep understanding of all the different factors in transformer design. My question is about a plug-in 2:1 step up/down transformer used for 120/240 volt conversion in a home. If such a device is plugged into a wall outlet what is the correct approach to wiring its ground pins?
Say the power supply into such a transformer includes a correctly wired ground. It’s connected to the transformer’s housing, and neutral/ground bonding is done correctly at the appropriate place within the building it is in.
On the isolated delivery side of the transformer, how should ground be dealt with? A) None. It is not possible to provide a safe and useful grounding function, so none should be provided. B) Output ground pin should be bonded to the transformer’s output neutral, but not to the case or the building ground. (isolated neutral/ground bond) C) Output ground pin should be bonded to the transformer casing and thereby to the building ground but not to the transformer’s output neutral. (Transformer output fully isolated). D) Output ground pin should be bonded to both the case AND to the neutral side of the transformer output. (Transformer output referenced to actual ground).
I can see benefits and problems with each of these, and do not understand enough of the theory and practice of either transformers or grounding safety to know what's right.