I see a lot of these transformers that claim to do both step-up and step-down in the same unit. At least one had a photo of the back side and there was a switch labeled to set it according to the input voltage. What I am curious about is how these are wired. Are they isolation transformers or autotransformers. In particular, is the wiring grounded? What I need to do is step 208 volts that comes from two hot wires of a USA style three-phase 208/120 circuit ... where the neutral is NOT available because it is a 208 volt circuit ... down to either 104 volts, or if possible 120 volts. Since a 208 or 240 volt circuit in the USA is made from two hot (120 volts relative to ground) wires, either at 120 degree phase angle for 208 volts, or at 180 degree phase angle for 240 volts, neither wire is a grounded/neutral. This means an autotransformer could be unsafe as a means to step 208 volts down to 104 volts, since neither of those wires will be grounded.