## This is either an autotransformer, or a regular transformer wired as an autotransformer, *not* an isolation transformer

The manufacturers of this transformer-unit most likely used an autotransformer, as all they are after is a voltage step-down, not isolation.  Even if they did use a two-winding transformer, they have wired it with a common neutral between the primary and secondary sides, which defeats any isolation provided by the transformer itself.  This is unlike an *isolation* transformer, which has no galvanic connection between current-carrying conductors on the primary and secondary sides.