I'm using 240 for voltage drop. The load is a receptacle fed from a subpanel. I know the size of the transformer,the fusing I want to use but, need help figuring out how to ground the system. In particular, how the system would be protected from a ground fault. I know the fuses will handle overloads and short circuits.

  • Are we talking a single receptacle or several receptacles, and what size transformer are you using here? – ThreePhaseEel Apr 15 '20 at 3:16
  • 1
    it is an isolating transformer or a non-isolating buck transformer? – Jasen Apr 15 '20 at 4:48
  • I think that we need more specific information or details – Ack Apr 15 '20 at 17:11

If you're using one of those cheap-@$$ "step down transformers" off Amazon, then you cannot do this safely. They are not UL listed, and are not rated for any of this.

If you obtain a 1.5 KVA transformer with an isolated secondary, that is 120V on one side and 240V on the other (these accept a variety of arrangements), then you connect the 240V side (jumpered for 240V) to the 240V obviously lol.

Then you connect the 120V side of the transformer to hot and neutral of your receptacle. The ground comes from the supply, and essentially bypasses the transformer.

And you should be installing this properly, not leaving it in a puke of wires all over the place.

Now if you really want to do it properly, the transformer should feed into a "main service panel" distinguished by tying into local ground wires and having its neutral-ground bond intact. That will assure the 120V hot + neutral cannot float more than 120V above local ground.

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