Why my Toroid Isolation Transformer has 112.3v to soil
First, the 1182 series are not truly "isolation transformers". At least not on the linked datasheet. They are regular transformers with electrically unconnected secondary winding. While the secondary winding is not connected, the area of windings overlap is huge along the toroidal core, and thus there is capacitive coupling, since the whole thing operates on AC.



My take on the difference in readings is that by design, the windings are made in multiple layers, so one end is closer to primary winding, and the capacitive coupling is higher, while the other end is likely on the surface of the transformer, and has higher distance from primary winging.

The value of capacitive coupling could be 1 nF - 2 nF, which is about 3 MOhms, so a high-impedance DMM will see some AC voltage between floating leads and earth ground. And the effective leakage will be about 30 uA, which will be easily grounded once you connect it to your workbench ground.

True "line isolation transformers" usually include a single-layer winding (for toroidal core, and a non-shorted copper foil in rectangular bobbins, as Jeroen3 commented) with only one end exposed, which is connected to enclosure ground. In this case the cross-talk between primary coil and secondary coils is minimized, see Section "Line Transformers"

  

from main Hammond transformer catalog.